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class="container padding-top--md padding-bottom--lg"><div class="row"><div class="col docItemCol_VOVn"><div class="docItemContainer_Djhp"><article><nav class="theme-doc-breadcrumbs breadcrumbsContainer_Z_bl" aria-label="Breadcrumbs"><ul class="breadcrumbs" itemscope="" itemtype="https://schema.org/BreadcrumbList"><li class="breadcrumbs__item"><a aria-label="Home page" class="breadcrumbs__link" href="/"><svg viewBox="0 0 24 24" class="breadcrumbHomeIcon_YNFT"><path d="M10 19v-5h4v5c0 .55.45 1 1 1h3c.55 0 1-.45 1-1v-7h1.7c.46 0 .68-.57.33-.87L12.67 3.6c-.38-.34-.96-.34-1.34 0l-8.36 7.53c-.34.3-.13.87.33.87H5v7c0 .55.45 1 1 1h3c.55 0 1-.45 1-1z" fill="currentColor"></path></svg></a></li><li class="breadcrumbs__item">Rules Documentation<meta itemprop="position" content="1"></li><li itemscope="" itemprop="itemListElement" itemtype="https://schema.org/ListItem" class="breadcrumbs__item breadcrumbs__item--active">Style Rule Set<meta itemprop="position" content="2"></li></ul></nav>Version: 1.23.8<div class="tocCollapsible_ETCw theme-doc-toc-mobile tocMobile_ITEo"><button type="button" class="clean-btn tocCollapsibleButton_TO0P">On this page</button></div><div class="theme-doc-markdown markdown"><header><h1>Style Rule Set</h1></header>The Style ruleset provides rules that assert the style of the code. This will help keep code in line with the given code style guidelines. <h3 class="anchor anchorWithStickyNavbar_LWe7" id="alsocouldbeapply">AlsoCouldBeApply<a href="#alsocouldbeapply" class="hash-link" aria-label="Direct link to AlsoCouldBeApply" title="Direct link to AlsoCouldBeApply"></a></h3> Detects when an <code>also</code> block contains only <code>it</code>-started expressions. By refactoring the <code>also</code> block to an <code>apply</code> block makes it so that all <code>it</code>s can be removed thus making the block more concise and easier to read. Active by default: No Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code">Noncompliant Code:<a href="#noncompliant-code" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">Buzz().also { it.init() it.block() } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code">Compliant Code:<a href="#compliant-code" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">Buzz().apply { init() block() } // Also compliant fun foo(a: Int): Int { return a.also { println(it) } } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="bracesonifstatements">BracesOnIfStatements<a href="#bracesonifstatements" class="hash-link" aria-label="Direct link to BracesOnIfStatements" title="Direct link to BracesOnIfStatements"></a></h3> This rule detects <code>if</code> statements which do not comply with the specified rules. Keeping braces consistent will improve readability and avoid possible errors. The available options are: <ul> <li><code>always</code>: forces braces on all <code>if</code> and <code>else</code> branches in the whole codebase.</li> <li><code>consistent</code>: ensures that braces are consistent within each <code>if</code>-<code>else if</code>-<code>else</code> chain. If there's a brace on one of the branches, all branches should have it.</li> <li><code>necessary</code>: forces no braces on any <code>if</code> and <code>else</code> branches in the whole codebase except where necessary for multi-statement branches.</li> <li><code>never</code>: forces no braces on any <code>if</code> and <code>else</code> branches in the whole codebase.</li> </ul> Single-line if-statement has no line break (\n): <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">if (a) b else c </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> Multi-line if-statement has at least one line break (\n): <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">if (a) b else c </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> Active by default: No Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="configuration-options">Configuration options:<a href="#configuration-options" class="hash-link" aria-label="Direct link to Configuration options:" title="Direct link to Configuration options:"></a></h4> <ul> <li> <code>singleLine</code> (default: <code>'never'</code>) single-line braces policy </li> <li> <code>multiLine</code> (default: <code>'always'</code>) multi-line braces policy </li> </ul> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-1">Noncompliant Code:<a href="#noncompliant-code-1" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">// singleLine = 'never' if (a) { b } else { c } if (a) { b } else c if (a) b else { c; d } // multiLine = 'never' if (a) { b } else { c } // singleLine = 'always' if (a) b else c if (a) { b } else c // multiLine = 'always' if (a) { b } else c // singleLine = 'consistent' if (a) b else { c } if (a) b else if (c) d else { e } // multiLine = 'consistent' if (a) b else { c } // singleLine = 'necessary' if (a) { b } else { c; d } // multiLine = 'necessary' if (a) { b c } else if (d) { e } else { f } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-1">Compliant Code:<a href="#compliant-code-1" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">// singleLine = 'never' if (a) b else c // multiLine = 'never' if (a) b else c // singleLine = 'always' if (a) { b } else { c } if (a) { b } else if (c) { d } // multiLine = 'always' if (a) { b } else { c } if (a) { b } else if (c) { d } // singleLine = 'consistent' if (a) b else c if (a) { b } else { c } if (a) { b } else { c; d } // multiLine = 'consistent' if (a) { b } else { c } if (a) b else c // singleLine = 'necessary' if (a) b else { c; d } // multiLine = 'necessary' if (a) { b c } else if (d) e else f </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="bracesonwhenstatements">BracesOnWhenStatements<a href="#bracesonwhenstatements" class="hash-link" aria-label="Direct link to BracesOnWhenStatements" title="Direct link to BracesOnWhenStatements"></a></h3> This rule detects <code>when</code> statements which do not comply with the specified policy. Keeping braces consistent will improve readability and avoid possible errors. Single-line <code>when</code> statement is: a <code>when</code> where each of the branches are single-line (has no line breaks <code>\n</code>). Multi-line <code>when</code> statement is: a <code>when</code> where at least one of the branches is multi-line (has a break line <code>\n</code>). Available options are: <ul> <li><code>never</code>: forces no braces on any branch. Tip: this is very strict, it will force a simple expression, like a single function call / expression. Extracting a function for "complex" logic is one way to adhere to this policy.</li> <li><code>necessary</code>: forces no braces on any branch except where necessary for multi-statement branches.</li> <li><code>consistent</code>: ensures that braces are consistent within <code>when</code> statement. If there are braces on one of the branches, all branches should have it.</li> <li><code>always</code>: forces braces on all branches.</li> </ul> Active by default: No Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="configuration-options-1">Configuration options:<a href="#configuration-options-1" class="hash-link" aria-label="Direct link to Configuration options:" title="Direct link to Configuration options:"></a></h4> <ul> <li> <code>singleLine</code> (default: <code>'necessary'</code>) single-line braces policy </li> <li> <code>multiLine</code> (default: <code>'consistent'</code>) multi-line braces policy </li> </ul> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-2">Noncompliant Code:<a href="#noncompliant-code-2" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">// singleLine = 'never' when (a) { 1 -> { f1() } // Not allowed. 2 -> f2() } // multiLine = 'never' when (a) { 1 -> { // Not allowed. f1() } 2 -> f2() } // singleLine = 'necessary' when (a) { 1 -> { f1() } // Unnecessary braces. 2 -> f2() } // multiLine = 'necessary' when (a) { 1 -> { // Unnecessary braces. f1() } 2 -> f2() } // singleLine = 'consistent' when (a) { 1 -> { f1() } 2 -> f2() } // multiLine = 'consistent' when (a) { 1 -> f1() // Missing braces. 2 -> { f2() f3() } } // singleLine = 'always' when (a) { 1 -> { f1() } 2 -> f2() // Missing braces. } // multiLine = 'always' when (a) { 1 -> f1() // Missing braces. 2 -> { f2() f3() } } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-2">Compliant Code:<a href="#compliant-code-2" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">// singleLine = 'never' when (a) { 1 -> f1() 2 -> f2() } // multiLine = 'never' when (a) { 1 -> f1() 2 -> f2() } // singleLine = 'necessary' when (a) { 1 -> f1() 2 -> { f2(); f3() } // Necessary braces because of multiple statements. } // multiLine = 'necessary' when (a) { 1 -> f1() 2 -> { // Necessary braces because of multiple statements. f2() f3() } } // singleLine = 'consistent' when (a) { 1 -> { f1() } 2 -> { f2() } } when (a) { 1 -> f1() 2 -> f2() } // multiLine = 'consistent' when (a) { 1 -> { f1() } 2 -> { f2() f3() } } // singleLine = 'always' when (a) { 1 -> { f1() } 2 -> { f2() } } // multiLine = 'always' when (a) { 1 -> { f1() } 2 -> { f2() f3() } } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="canbenonnullable">CanBeNonNullable<a href="#canbenonnullable" class="hash-link" aria-label="Direct link to CanBeNonNullable" title="Direct link to CanBeNonNullable"></a></h3> This rule inspects variables marked as nullable and reports which could be declared as non-nullable instead. It's preferred to not have functions that do "nothing". A function that does nothing when the value is null hides the logic, so it should not allow null values in the first place. It is better to move the null checks up around the calls, instead of having it inside the function. This could lead to less nullability overall in the codebase. Active by default: No Requires Type Resolution Debt: 10min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-3">Noncompliant Code:<a href="#noncompliant-code-3" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">class A { var a: Int? = 5 fun foo() { a = 6 } } class A { val a: Int? get() = 5 } fun foo(a: Int?) { val b = a!! + 2 } fun foo(a: Int?) { if (a != null) { println(a) } } fun foo(a: Int?) { if (a == null) return println(a) } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-3">Compliant Code:<a href="#compliant-code-3" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">class A { var a: Int = 5 fun foo() { a = 6 } } class A { val a: Int get() = 5 } fun foo(a: Int) { val b = a + 2 } fun foo(a: Int) { println(a) } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="cascadingcallwrapping">CascadingCallWrapping<a href="#cascadingcallwrapping" class="hash-link" aria-label="Direct link to CascadingCallWrapping" title="Direct link to CascadingCallWrapping"></a></h3> Requires that all chained calls are placed on a new line if a preceding one is. Active by default: No Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="configuration-options-2">Configuration options:<a href="#configuration-options-2" class="hash-link" aria-label="Direct link to Configuration options:" title="Direct link to Configuration options:"></a></h4> <ul> <li> <code>includeElvis</code> (default: <code>true</code>) require trailing elvis expressions to be wrapped on a new line </li> </ul> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-4">Noncompliant Code:<a href="#noncompliant-code-4" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">foo() .bar().baz() </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-4">Compliant Code:<a href="#compliant-code-4" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">foo().bar().baz() foo() .bar() .baz() </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="classordering">ClassOrdering<a href="#classordering" class="hash-link" aria-label="Direct link to ClassOrdering" title="Direct link to ClassOrdering"></a></h3> This rule ensures class contents are ordered as follows as recommended by the Kotlin <a href="https://kotlinlang.org/docs/coding-conventions.html#class-layout" target="_blank" rel="noopener noreferrer">Coding Conventions</a>: <ul> <li>Property declarations and initializer blocks</li> <li>Secondary constructors</li> <li>Method declarations</li> <li>Companion object</li> </ul> Active by default: No Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-5">Noncompliant Code:<a href="#noncompliant-code-5" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">class OutOfOrder { companion object { const val IMPORTANT_VALUE = 3 } fun returnX(): Int { return x } private val x = 2 } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-5">Compliant Code:<a href="#compliant-code-5" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">class InOrder { private val x = 2 fun returnX(): Int { return x } companion object { const val IMPORTANT_VALUE = 3 } } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="collapsibleifstatements">CollapsibleIfStatements<a href="#collapsibleifstatements" class="hash-link" aria-label="Direct link to CollapsibleIfStatements" title="Direct link to CollapsibleIfStatements"></a></h3> This rule detects <code>if</code> statements which can be collapsed. This can reduce nesting and help improve readability. However, carefully consider whether merging the if statements actually improves readability, as collapsing the statements may hide some edge cases from the reader. Active by default: No Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-6">Noncompliant Code:<a href="#noncompliant-code-6" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">val i = 1 if (i > 0) { if (i < 5) { println(i) } } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-6">Compliant Code:<a href="#compliant-code-6" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">val i = 1 if (i > 0 && i < 5) { println(i) } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="dataclasscontainsfunctions">DataClassContainsFunctions<a href="#dataclasscontainsfunctions" class="hash-link" aria-label="Direct link to DataClassContainsFunctions" title="Direct link to DataClassContainsFunctions"></a></h3> This rule reports functions inside data classes which have not been marked as a conversion function. Data classes should mainly be used to store data. This rule assumes that they should not contain any extra functions aside functions that help with converting objects from/to one another. Data classes will automatically have a generated <code>equals</code>, <code>toString</code> and <code>hashCode</code> function by the compiler. Active by default: No Debt: 20min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="configuration-options-3">Configuration options:<a href="#configuration-options-3" class="hash-link" aria-label="Direct link to Configuration options:" title="Direct link to Configuration options:"></a></h4> <ul> <li> <code>conversionFunctionPrefix</code> (default: <code>['to']</code>) allowed conversion function names </li> <li> <code>allowOperators</code> (default: <code>false</code>) allows overloading an operator </li> </ul> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-7">Noncompliant Code:<a href="#noncompliant-code-7" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">data class DataClassWithFunctions(val i: Int) { fun foo() { } } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="dataclassshouldbeimmutable">DataClassShouldBeImmutable<a href="#dataclassshouldbeimmutable" class="hash-link" aria-label="Direct link to DataClassShouldBeImmutable" title="Direct link to DataClassShouldBeImmutable"></a></h3> This rule reports mutable properties inside data classes. Data classes should mainly be used to store immutable data. This rule assumes that they should not contain any mutable properties. Active by default: No Debt: 20min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-8">Noncompliant Code:<a href="#noncompliant-code-8" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">data class MutableDataClass(var i: Int) { var s: String? = null } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-7">Compliant Code:<a href="#compliant-code-7" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">data class ImmutableDataClass( val i: Int, val s: String? ) </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="destructuringdeclarationwithtoomanyentries">DestructuringDeclarationWithTooManyEntries<a href="#destructuringdeclarationwithtoomanyentries" class="hash-link" aria-label="Direct link to DestructuringDeclarationWithTooManyEntries" title="Direct link to DestructuringDeclarationWithTooManyEntries"></a></h3> Destructuring declarations with too many entries are hard to read and understand. To increase readability they should be refactored to reduce the number of entries or avoid using a destructuring declaration. Active by default: Yes - Since v1.21.0 Debt: 10min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="configuration-options-4">Configuration options:<a href="#configuration-options-4" class="hash-link" aria-label="Direct link to Configuration options:" title="Direct link to Configuration options:"></a></h4> <ul> <li> <code>maxDestructuringEntries</code> (default: <code>3</code>) maximum allowed elements in a destructuring declaration </li> </ul> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-9">Noncompliant Code:<a href="#noncompliant-code-9" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">data class TooManyElements(val a: Int, val b: Int, val c: Int, val d: Int) val (a, b, c, d) = TooManyElements(1, 2, 3, 4) </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-8">Compliant Code:<a href="#compliant-code-8" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">data class FewerElements(val a: Int, val b: Int, val c: Int) val (a, b, c) = TooManyElements(1, 2, 3) </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="doublenegativelambda">DoubleNegativeLambda<a href="#doublenegativelambda" class="hash-link" aria-label="Direct link to DoubleNegativeLambda" title="Direct link to DoubleNegativeLambda"></a></h3> Detects negation in lambda blocks where the function name is also in the negative (like <code>takeUnless</code>). A double negative is harder to read than a positive. In particular, if there are multiple conditions with <code>&&</code> etc. inside the lambda, then the reader may need to unpack these using DeMorgan's laws. Consider rewriting the lambda to use a positive version of the function (like <code>takeIf</code>). Active by default: No Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="configuration-options-5">Configuration options:<a href="#configuration-options-5" class="hash-link" aria-label="Direct link to Configuration options:" title="Direct link to Configuration options:"></a></h4> <ul> <li> <code>negativeFunctions</code> (default: <code>['takeUnless', 'none']</code>) Function names expressed in the negative that can form double negatives with their lambda blocks. These are grouped together with a recommendation to use a positive counterpart, or <code>null</code> if this is unknown. </li> <li> <code>negativeFunctionNameParts</code> (default: <code>['not', 'non']</code>) Function name parts to look for in the lambda block when deciding if the lambda contains a negative. </li> </ul> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-10">Noncompliant Code:<a href="#noncompliant-code-10" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">fun Int.evenOrNull() = takeUnless { it % 2 != 0 } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-9">Compliant Code:<a href="#compliant-code-9" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">fun Int.evenOrNull() = takeIf { it % 2 == 0 } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="equalsnullcall">EqualsNullCall<a href="#equalsnullcall" class="hash-link" aria-label="Direct link to EqualsNullCall" title="Direct link to EqualsNullCall"></a></h3> To compare an object with <code>null</code> prefer using <code>==</code>. This rule detects and reports instances in the code where the <code>equals()</code> method is used to compare a value with <code>null</code>. Active by default: Yes - Since v1.2.0 Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-11">Noncompliant Code:<a href="#noncompliant-code-11" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">fun isNull(str: String) = str.equals(null) </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-10">Compliant Code:<a href="#compliant-code-10" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">fun isNull(str: String) = str == null </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="equalsonsignatureline">EqualsOnSignatureLine<a href="#equalsonsignatureline" class="hash-link" aria-label="Direct link to EqualsOnSignatureLine" title="Direct link to EqualsOnSignatureLine"></a></h3> Requires that the equals sign, when used for an expression style function, is on the same line as the rest of the function signature. Active by default: No Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-12">Noncompliant Code:<a href="#noncompliant-code-12" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">fun stuff(): Int = 5 fun <V> foo(): Int where V : Int = 5 </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-11">Compliant Code:<a href="#compliant-code-11" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">fun stuff() = 5 fun stuff() = foo.bar() fun <V> foo(): Int where V : Int = 5 </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="explicitcollectionelementaccessmethod">ExplicitCollectionElementAccessMethod<a href="#explicitcollectionelementaccessmethod" class="hash-link" aria-label="Direct link to ExplicitCollectionElementAccessMethod" title="Direct link to ExplicitCollectionElementAccessMethod"></a></h3> In Kotlin functions <code>get</code> or <code>set</code> can be replaced with the shorter operator — <code>[]</code>, see <a href="https://kotlinlang.org/docs/operator-overloading.html#indexed-access-operator" target="_blank" rel="noopener noreferrer">Indexed access operator</a>. Prefer the usage of the indexed access operator <code>[]</code> for map or list element access or insert methods. Active by default: No Requires Type Resolution Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-13">Noncompliant Code:<a href="#noncompliant-code-13" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">val map = mutableMapOf<String, String>() map.put("key", "value") val value = map.get("key") </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-12">Compliant Code:<a href="#compliant-code-12" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">val map = mutableMapOf<String, String>() map["key"] = "value" val value = map["key"] </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="explicititlambdaparameter">ExplicitItLambdaParameter<a href="#explicititlambdaparameter" class="hash-link" aria-label="Direct link to ExplicitItLambdaParameter" title="Direct link to ExplicitItLambdaParameter"></a></h3> Lambda expressions are one of the core features of the language. They often include very small chunks of code using only one parameter. In this cases Kotlin can supply the implicit <code>it</code> parameter to make code more concise. It fits most use cases, but when faced larger or nested chunks of code, you might want to add an explicit name for the parameter. Naming it just <code>it</code> is meaningless and only makes your code misleading, especially when dealing with nested functions. Active by default: Yes - Since v1.21.0 Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-14">Noncompliant Code:<a href="#noncompliant-code-14" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">a?.let { it -> it.plus(1) } foo.flatMapObservable { it -> Observable.fromIterable(it) } listOfPairs.map(::second).forEach { it -> it.execute() } collection.zipWithNext { it, next -> Pair(it, next) } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-13">Compliant Code:<a href="#compliant-code-13" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">a?.let { it.plus(1) } // Much better to use implicit it a?.let { value: Int -> value.plus(1) } // Better as states the type more clearly foo.flatMapObservable(Observable::fromIterable) // Here we can have a method reference // For multiline blocks it is usually better come up with a clear and more meaningful name listOfPairs.map(::second).forEach { apiRequest -> apiRequest.execute() } // Lambdas with multiple parameter should be named clearly, using it for one of them can be confusing collection.zipWithNext { prev, next -> Pair(prev, next) } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="expressionbodysyntax">ExpressionBodySyntax<a href="#expressionbodysyntax" class="hash-link" aria-label="Direct link to ExpressionBodySyntax" title="Direct link to ExpressionBodySyntax"></a></h3> Functions which only contain a <code>return</code> statement can be collapsed to an expression body. This shortens and cleans up the code. Active by default: No Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="configuration-options-6">Configuration options:<a href="#configuration-options-6" class="hash-link" aria-label="Direct link to Configuration options:" title="Direct link to Configuration options:"></a></h4> <ul> <li> <code>includeLineWrapping</code> (default: <code>false</code>) include return statements with line wraps in it </li> </ul> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-15">Noncompliant Code:<a href="#noncompliant-code-15" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">fun stuff(): Int { return 5 } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-14">Compliant Code:<a href="#compliant-code-14" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">fun stuff() = 5 fun stuff() { return moreStuff() .getStuff() .stuffStuff() } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="forbiddenannotation">ForbiddenAnnotation<a href="#forbiddenannotation" class="hash-link" aria-label="Direct link to ForbiddenAnnotation" title="Direct link to ForbiddenAnnotation"></a></h3> This rule allows to set a list of forbidden annotations. This can be used to discourage the use of language annotations which do not require explicit import. Active by default: No Requires Type Resolution Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="configuration-options-7">Configuration options:<a href="#configuration-options-7" class="hash-link" aria-label="Direct link to Configuration options:" title="Direct link to Configuration options:"></a></h4> <ul> <li> <code>annotations</code> (default: <code>['java.lang.SuppressWarnings', 'java.lang.Deprecated', 'java.lang.annotation.Documented', 'java.lang.annotation.Target', 'java.lang.annotation.Retention', 'java.lang.annotation.Repeatable', 'java.lang.annotation.Inherited']</code>) List of fully qualified annotation classes which are forbidden. </li> </ul> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-16">Noncompliant Code:<a href="#noncompliant-code-16" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">@SuppressWarnings("unused") class SomeClass() </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-15">Compliant Code:<a href="#compliant-code-15" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">@Suppress("unused") class SomeClass() </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="forbiddencomment">ForbiddenComment<a href="#forbiddencomment" class="hash-link" aria-label="Direct link to ForbiddenComment" title="Direct link to ForbiddenComment"></a></h3> This rule allows to set a list of comments which are forbidden in the codebase and should only be used during development. Offending code comments will then be reported. The regular expressions in <code>comments</code> list will have the following behaviors while matching the comments: <ul> <li>Each comment will be handled individually. <ul> <li>single line comments are always separate, consecutive lines are not merged.</li> <li>multi line comments are not split up, the regex will be applied to the whole comment.</li> <li>KDoc comments are not split up, the regex will be applied to the whole comment.</li> </ul> </li> <li>The following comment delimiters (and indentation before them) are removed before applying the regex: <code>//</code>, <code>// </code>, <code>/*</code>, <code>/* </code>, <code>/**</code>, <code>*</code> aligners, <code>*/</code>, <code> */</code></li> <li>The regex is applied as a multiline regex, see <a href="https://www.regular-expressions.info/anchors.html" target="_blank" rel="noopener noreferrer">Anchors</a> for more info. To match the start and end of each line, use <code>^</code> and <code>$</code>. To match the start and end of the whole comment, use <code>\A</code> and <code>\Z</code>. To turn off multiline, use <code>(?-m)</code> at the start of your regex.</li> <li>The regex is applied with dotall semantics, meaning <code>.</code> will match any character including newlines, this is to ensure that freeform line-wrapping doesn't mess with simple regexes. To turn off this behavior, use <code>(?-s)</code> at the start of your regex, or use <code>[^\r\n]*</code> instead of <code>.*</code>.</li> <li>The regex will be searched using "contains" semantics not "matches", so partial comment matches will flag forbidden comments. In practice this means there's no need to start and end the regex with <code>.*</code>.</li> </ul> The rule can be configured to add extra comments to the list of forbidden comments, here are some examples: <div class="language-yaml codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-yaml codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">ForbiddenComment: comments: # Repeat the default configuration if it's still needed. - reason: 'Forbidden FIXME todo marker in comment, please fix the problem.' value: 'FIXME:' - reason: 'Forbidden STOPSHIP todo marker in comment, please address the problem before shipping the code.' value: 'STOPSHIP:' - reason: 'Forbidden TODO todo marker in comment, please do the changes.' value: 'TODO:' # Add additional patterns to the list. - reason: 'Authors are not recorded in KDoc.' value: '@author' - reason: 'REVIEW markers are not allowed in production code, only use before PR is merged.' value: '^\s*(?i)REVIEW\b' # Non-compliant: // REVIEW this code before merging. # Compliant: // Preview will show up here. - reason: 'Use @androidx.annotation.VisibleForTesting(otherwise = VisibleForTesting.PRIVATE) instead.' value: '^private$' # Non-compliant: /*private*/fun f() { } - reason: 'KDoc tag should have a value.' value: '^\s*@(?!suppress|hide)\w+\s*$' # Non-compliant: /** ... @see */ # Compliant: /** ... @throws IOException when there's a network problem */ - reason: 'include an issue link at the beginning preceded by a space' value: 'BUG:(?! https://github\.com/company/repo/issues/\d+).*' </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> By default the commonly used todo markers are forbidden: <code>TODO:</code>, <code>FIXME:</code> and <code>STOPSHIP:</code>. Active by default: Yes - Since v1.0.0 Debt: 10min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="configuration-options-8">Configuration options:<a href="#configuration-options-8" class="hash-link" aria-label="Direct link to Configuration options:" title="Direct link to Configuration options:"></a></h4> <ul> <li> <del><code>values</code></del> (default: <code>[]</code>) Deprecated: Use <code>comments</code> instead, make sure you escape your text for Regular Expressions. forbidden comment strings </li> <li> <code>comments</code> (default: <code>['FIXME:', 'STOPSHIP:', 'TODO:']</code>) forbidden comment string patterns </li> <li> <code>allowedPatterns</code> (default: <code>''</code>) ignores comments which match the specified regular expression. For example <code>Ticket|Task</code>. </li> <li> <del><code>customMessage</code></del> (default: <code>''</code>) Deprecated: Use <code>comments</code> and provide <code>reason</code> against each <code>value</code>. error message which overrides the default one </li> </ul> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-17">Noncompliant Code:<a href="#noncompliant-code-17" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">val a = "" // TODO: remove please /** * FIXME: this is a hack */ fun foo() { } /* STOPSHIP: */ </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="forbiddenimport">ForbiddenImport<a href="#forbiddenimport" class="hash-link" aria-label="Direct link to ForbiddenImport" title="Direct link to ForbiddenImport"></a></h3> Reports all imports that are forbidden. This rule allows to set a list of forbidden [imports]. This can be used to discourage the use of unstable, experimental or deprecated APIs. Active by default: No Debt: 10min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="configuration-options-9">Configuration options:<a href="#configuration-options-9" class="hash-link" aria-label="Direct link to Configuration options:" title="Direct link to Configuration options:"></a></h4> <ul> <li> <code>imports</code> (default: <code>[]</code>) imports which should not be used </li> <li> <code>forbiddenPatterns</code> (default: <code>''</code>) reports imports which match the specified regular expression. For example <code>net.*R</code>. </li> </ul> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-18">Noncompliant Code:<a href="#noncompliant-code-18" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">import kotlin.jvm.JvmField import kotlin.SinceKotlin </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="forbiddenmethodcall">ForbiddenMethodCall<a href="#forbiddenmethodcall" class="hash-link" aria-label="Direct link to ForbiddenMethodCall" title="Direct link to ForbiddenMethodCall"></a></h3> Reports all method or constructor invocations that are forbidden. This rule allows to set a list of forbidden [methods] or constructors. This can be used to discourage the use of unstable, experimental or deprecated methods, especially for methods imported from external libraries. Active by default: No Requires Type Resolution Debt: 10min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="configuration-options-10">Configuration options:<a href="#configuration-options-10" class="hash-link" aria-label="Direct link to Configuration options:" title="Direct link to Configuration options:"></a></h4> <ul> <li> <code>methods</code> (default: <code>['kotlin.io.print', 'kotlin.io.println']</code>) List of fully qualified method signatures which are forbidden. Methods can be defined without full signature (i.e. <code>java.time.LocalDate.now</code>) which will report calls of all methods with this name or with full signature (i.e. <code>java.time.LocalDate(java.time.Clock)</code>) which would report only call with this concrete signature. If you want to forbid an extension function like <code>fun String.hello(a: Int)</code> you should add the receiver parameter as the first parameter like this: <code>hello(kotlin.String, kotlin.Int)</code>. To forbid constructor calls you need to define them with <code><init></code>, for example <code>java.util.Date.<init></code>. To forbid calls involving type parameters, omit them, for example <code>fun hello(args: Array<Any>)</code> is referred to as simply <code>hello(kotlin.Array)</code> (also the signature for vararg parameters). To forbid methods from the companion object reference the Companion class, for example as <code>TestClass.Companion.hello()</code> (even if it is marked <code>@JvmStatic</code>). </li> </ul> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-19">Noncompliant Code:<a href="#noncompliant-code-19" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">import java.lang.System fun main() { System.gc() System::gc } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="forbiddensuppress">ForbiddenSuppress<a href="#forbiddensuppress" class="hash-link" aria-label="Direct link to ForbiddenSuppress" title="Direct link to ForbiddenSuppress"></a></h3> Report suppressions of all forbidden rules. This rule allows to set a list of [rules] whose suppression is forbidden. This can be used to discourage the abuse of the <code>Suppress</code> and <code>SuppressWarnings</code> annotations. This rule is not capable of reporting suppression of itself, as that's a language feature with precedence. Active by default: No Debt: 10min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="configuration-options-11">Configuration options:<a href="#configuration-options-11" class="hash-link" aria-label="Direct link to Configuration options:" title="Direct link to Configuration options:"></a></h4> <ul> <li> <code>rules</code> (default: <code>[]</code>) Rules whose suppression is forbidden. </li> </ul> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-20">Noncompliant Code:<a href="#noncompliant-code-20" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">package foo // When the rule "MaximumLineLength" is forbidden @Suppress("MaximumLineLength", "UNCHECKED_CAST") class Bar </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-16">Compliant Code:<a href="#compliant-code-16" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">package foo // When the rule "MaximumLineLength" is forbidden @Suppress("UNCHECKED_CAST") class Bar </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="forbiddenvoid">ForbiddenVoid<a href="#forbiddenvoid" class="hash-link" aria-label="Direct link to ForbiddenVoid" title="Direct link to ForbiddenVoid"></a></h3> This rule detects usages of <code>Void</code> and reports them as forbidden. The Kotlin type <code>Unit</code> should be used instead. This type corresponds to the <code>Void</code> class in Java and has only one value - the <code>Unit</code> object. Active by default: Yes - Since v1.21.0 Requires Type Resolution Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="configuration-options-12">Configuration options:<a href="#configuration-options-12" class="hash-link" aria-label="Direct link to Configuration options:" title="Direct link to Configuration options:"></a></h4> <ul> <li> <code>ignoreOverridden</code> (default: <code>false</code>) ignores void types in signatures of overridden functions </li> <li> <code>ignoreUsageInGenerics</code> (default: <code>false</code>) ignore void types as generic arguments </li> </ul> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-21">Noncompliant Code:<a href="#noncompliant-code-21" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">runnable: () -> Void var aVoid: Void? = null </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-17">Compliant Code:<a href="#compliant-code-17" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">runnable: () -> Unit Void::class </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="functiononlyreturningconstant">FunctionOnlyReturningConstant<a href="#functiononlyreturningconstant" class="hash-link" aria-label="Direct link to FunctionOnlyReturningConstant" title="Direct link to FunctionOnlyReturningConstant"></a></h3> A function that only returns a single constant can be misleading. Instead, prefer declaring the constant as a <code>const val</code>. Active by default: Yes - Since v1.2.0 Debt: 10min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="configuration-options-13">Configuration options:<a href="#configuration-options-13" class="hash-link" aria-label="Direct link to Configuration options:" title="Direct link to Configuration options:"></a></h4> <ul> <li> <code>ignoreOverridableFunction</code> (default: <code>true</code>) if overriden functions should be ignored </li> <li> <code>ignoreActualFunction</code> (default: <code>true</code>) if actual functions should be ignored </li> <li> <code>excludedFunctions</code> (default: <code>[]</code>) excluded functions </li> <li> <del><code>excludeAnnotatedFunction</code></del> (default: <code>[]</code>) Deprecated: Use <code>ignoreAnnotated</code> instead allows to provide a list of annotations that disable this check </li> </ul> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-22">Noncompliant Code:<a href="#noncompliant-code-22" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">fun functionReturningConstantString() = "1" </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-18">Compliant Code:<a href="#compliant-code-18" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">const val constantString = "1" </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="loopwithtoomanyjumpstatements">LoopWithTooManyJumpStatements<a href="#loopwithtoomanyjumpstatements" class="hash-link" aria-label="Direct link to LoopWithTooManyJumpStatements" title="Direct link to LoopWithTooManyJumpStatements"></a></h3> Loops which contain multiple <code>break</code> or <code>continue</code> statements are hard to read and understand. To increase readability they should be refactored into simpler loops. Active by default: Yes - Since v1.2.0 Debt: 10min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="configuration-options-14">Configuration options:<a href="#configuration-options-14" class="hash-link" aria-label="Direct link to Configuration options:" title="Direct link to Configuration options:"></a></h4> <ul> <li> <code>maxJumpCount</code> (default: <code>1</code>) maximum allowed jumps in a loop </li> </ul> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-23">Noncompliant Code:<a href="#noncompliant-code-23" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">val strs = listOf("foo, bar") for (str in strs) { if (str == "bar") { break } else { continue } } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="magicnumber">MagicNumber<a href="#magicnumber" class="hash-link" aria-label="Direct link to MagicNumber" title="Direct link to MagicNumber"></a></h3> This rule detects and reports usages of magic numbers in the code. Prefer defining constants with clear names describing what the magic number means. Active by default: Yes - Since v1.0.0 Debt: 10min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="configuration-options-15">Configuration options:<a href="#configuration-options-15" class="hash-link" aria-label="Direct link to Configuration options:" title="Direct link to Configuration options:"></a></h4> <ul> <li> <code>ignoreNumbers</code> (default: <code>['-1', '0', '1', '2']</code>) numbers which do not count as magic numbers </li> <li> <code>ignoreHashCodeFunction</code> (default: <code>true</code>) whether magic numbers in hashCode functions should be ignored </li> <li> <code>ignorePropertyDeclaration</code> (default: <code>false</code>) whether magic numbers in property declarations should be ignored </li> <li> <code>ignoreLocalVariableDeclaration</code> (default: <code>false</code>) whether magic numbers in local variable declarations should be ignored </li> <li> <code>ignoreConstantDeclaration</code> (default: <code>true</code>) whether magic numbers in constant declarations should be ignored </li> <li> <code>ignoreCompanionObjectPropertyDeclaration</code> (default: <code>true</code>) whether magic numbers in companion object declarations should be ignored </li> <li> <code>ignoreAnnotation</code> (default: <code>false</code>) whether magic numbers in annotations should be ignored </li> <li> <code>ignoreNamedArgument</code> (default: <code>true</code>) whether magic numbers in named arguments should be ignored </li> <li> <code>ignoreEnums</code> (default: <code>false</code>) whether magic numbers in enums should be ignored </li> <li> <code>ignoreRanges</code> (default: <code>false</code>) whether magic numbers in ranges should be ignored </li> <li> <code>ignoreExtensionFunctions</code> (default: <code>true</code>) whether magic numbers as subject of an extension function should be ignored </li> </ul> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-24">Noncompliant Code:<a href="#noncompliant-code-24" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">class User { fun checkName(name: String) { if (name.length > 42) { throw IllegalArgumentException("username is too long") } // ... } } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-19">Compliant Code:<a href="#compliant-code-19" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">class User { fun checkName(name: String) { if (name.length > MAX_USERNAME_SIZE) { throw IllegalArgumentException("username is too long") } // ... } companion object { private const val MAX_USERNAME_SIZE = 42 } } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="mandatorybracesloops">MandatoryBracesLoops<a href="#mandatorybracesloops" class="hash-link" aria-label="Direct link to MandatoryBracesLoops" title="Direct link to MandatoryBracesLoops"></a></h3> This rule detects multi-line <code>for</code> and <code>while</code> loops which do not have braces. Adding braces would improve readability and avoid possible errors. Active by default: No Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-25">Noncompliant Code:<a href="#noncompliant-code-25" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">for (i in 0..10) println(i) while (true) println("Hello, world") do println("Hello, world") while (true) </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-20">Compliant Code:<a href="#compliant-code-20" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">for (i in 0..10) { println(i) } for (i in 0..10) println(i) while (true) { println("Hello, world") } while (true) println("Hello, world") do { println("Hello, world") } while (true) do println("Hello, world") while (true) </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="maxchainedcallsonsameline">MaxChainedCallsOnSameLine<a href="#maxchainedcallsonsameline" class="hash-link" aria-label="Direct link to MaxChainedCallsOnSameLine" title="Direct link to MaxChainedCallsOnSameLine"></a></h3> Limits the number of chained calls which can be placed on a single line. Active by default: No Requires Type Resolution Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="configuration-options-16">Configuration options:<a href="#configuration-options-16" class="hash-link" aria-label="Direct link to Configuration options:" title="Direct link to Configuration options:"></a></h4> <ul> <li> <code>maxChainedCalls</code> (default: <code>5</code>) maximum chained calls allowed on a single line </li> </ul> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-26">Noncompliant Code:<a href="#noncompliant-code-26" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">a().b().c().d().e().f() </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-21">Compliant Code:<a href="#compliant-code-21" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">a().b().c() .d().e().f() </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="maxlinelength">MaxLineLength<a href="#maxlinelength" class="hash-link" aria-label="Direct link to MaxLineLength" title="Direct link to MaxLineLength"></a></h3> This rule reports lines of code which exceed a defined maximum line length. Long lines might be hard to read on smaller screens or printouts. Additionally, having a maximum line length in the codebase will help make the code more uniform. Active by default: Yes - Since v1.0.0 Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="configuration-options-17">Configuration options:<a href="#configuration-options-17" class="hash-link" aria-label="Direct link to Configuration options:" title="Direct link to Configuration options:"></a></h4> <ul> <li> <code>maxLineLength</code> (default: <code>120</code>) maximum line length </li> <li> <code>excludePackageStatements</code> (default: <code>true</code>) if package statements should be ignored </li> <li> <code>excludeImportStatements</code> (default: <code>true</code>) if import statements should be ignored </li> <li> <code>excludeCommentStatements</code> (default: <code>false</code>) if comment statements should be ignored </li> <li> <code>excludeRawStrings</code> (default: <code>true</code>) if raw strings should be ignored </li> </ul> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="maybeconst">MayBeConst<a href="#maybeconst" class="hash-link" aria-label="Direct link to MayBeConst" title="Direct link to MayBeConst"></a></h3> This rule identifies and reports properties (<code>val</code>) that may be <code>const val</code> instead. Using <code>const val</code> can lead to better performance of the resulting bytecode as well as better interoperability with Java. Active by default: Yes - Since v1.2.0 Debt: 5min Aliases: MayBeConstant <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-27">Noncompliant Code:<a href="#noncompliant-code-27" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">val myConstant = "abc" </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-22">Compliant Code:<a href="#compliant-code-22" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">const val MY_CONSTANT = "abc" </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="modifierorder">ModifierOrder<a href="#modifierorder" class="hash-link" aria-label="Direct link to ModifierOrder" title="Direct link to ModifierOrder"></a></h3> This rule reports cases in the code where modifiers are not in the correct order. The default modifier order is taken from: <a href="https://kotlinlang.org/docs/coding-conventions.html#modifiers-order" target="_blank" rel="noopener noreferrer">Modifiers order</a> Active by default: Yes - Since v1.0.0 Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-28">Noncompliant Code:<a href="#noncompliant-code-28" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">lateinit internal val str: String </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-23">Compliant Code:<a href="#compliant-code-23" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">internal lateinit val str: String </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="multilinelambdaitparameter">MultilineLambdaItParameter<a href="#multilinelambdaitparameter" class="hash-link" aria-label="Direct link to MultilineLambdaItParameter" title="Direct link to MultilineLambdaItParameter"></a></h3> Lambda expressions are very useful in a lot of cases, and they often include very small chunks of code using only one parameter. In this cases Kotlin can supply the implicit <code>it</code> parameter to make code more concise. However, when you are dealing with lambdas that contain multiple statements, you might end up with code that is hard to read if you don't specify a readable, descriptive parameter name explicitly. Active by default: No Requires Type Resolution Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-29">Noncompliant Code:<a href="#noncompliant-code-29" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">val digits = 1234.let { println(it) listOf(it) } val digits = 1234.let { it -> println(it) listOf(it) } val flat = listOf(listOf(1), listOf(2)).mapIndexed { index, it -> println(it) it + index } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-24">Compliant Code:<a href="#compliant-code-24" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">val digits = 1234.let { explicitParameterName -> println(explicitParameterName) listOf(explicitParameterName) } val lambda = { item: Int, that: String -> println(item) item.toString() + that } val digits = 1234.let { listOf(it) } val digits = 1234.let { listOf(it) } val digits = 1234.let { it -> listOf(it) } val digits = 1234.let { it -> listOf(it) } val digits = 1234.let { explicit -> listOf(explicit) } val digits = 1234.let { explicit -> listOf(explicit) } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="multilinerawstringindentation">MultilineRawStringIndentation<a href="#multilinerawstringindentation" class="hash-link" aria-label="Direct link to MultilineRawStringIndentation" title="Direct link to MultilineRawStringIndentation"></a></h3> This rule ensures that raw strings have a consistent indentation. The content of a multi line raw string should have the same indentation as the enclosing expression plus the configured indentSize. The closing triple-quotes (<code>"""</code>) must have the same indentation as the enclosing expression. Active by default: No Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="configuration-options-18">Configuration options:<a href="#configuration-options-18" class="hash-link" aria-label="Direct link to Configuration options:" title="Direct link to Configuration options:"></a></h4> <ul> <li> <code>indentSize</code> (default: <code>4</code>) indentation size </li> <li> <code>trimmingMethods</code> (default: <code>['trimIndent', 'trimMargin']</code>) allows to provide a list of multiline string trimming methods </li> </ul> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-30">Noncompliant Code:<a href="#noncompliant-code-30" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">val a = """ Hello World! How are you? """.trimMargin() val a = """ Hello World! How are you? """.trimMargin() </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-25">Compliant Code:<a href="#compliant-code-25" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">val a = """ Hello World! How are you? """.trimMargin() val a = """ Hello World! How are you? """.trimMargin() </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="nestedclassesvisibility">NestedClassesVisibility<a href="#nestedclassesvisibility" class="hash-link" aria-label="Direct link to NestedClassesVisibility" title="Direct link to NestedClassesVisibility"></a></h3> Nested classes inherit their visibility from the parent class and are often used to implement functionality local to the class it is nested in. These nested classes can't have a higher visibility than their parent. However, the visibility can be further restricted by using a private modifier for instance. In internal classes the explicit public modifier for nested classes is misleading and thus unnecessary, because the nested class still has an internal visibility. Active by default: Yes - Since v1.16.0 Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-31">Noncompliant Code:<a href="#noncompliant-code-31" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">internal class Outer { // explicit public modifier still results in an internal nested class public class Nested } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-26">Compliant Code:<a href="#compliant-code-26" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">internal class Outer { class Nested1 internal class Nested2 } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="newlineatendoffile">NewLineAtEndOfFile<a href="#newlineatendoffile" class="hash-link" aria-label="Direct link to NewLineAtEndOfFile" title="Direct link to NewLineAtEndOfFile"></a></h3> This rule reports files which do not end with a line separator. Active by default: Yes - Since v1.0.0 Debt: 5min <h3 class="anchor anchorWithStickyNavbar_LWe7" id="notabs">NoTabs<a href="#notabs" class="hash-link" aria-label="Direct link to NoTabs" title="Direct link to NoTabs"></a></h3> This rule reports if tabs are used in Kotlin files. According to <a href="https://android.github.io/kotlin-guides/style.html#whitespace-characters" target="_blank" rel="noopener noreferrer">Google's Kotlin style guide</a> the only whitespace chars that are allowed in a source file are the line terminator sequence and the ASCII horizontal space character (0x20). Strings containing tabs are allowed. Active by default: No Debt: 5min <h3 class="anchor anchorWithStickyNavbar_LWe7" id="nullablebooleancheck">NullableBooleanCheck<a href="#nullablebooleancheck" class="hash-link" aria-label="Direct link to NullableBooleanCheck" title="Direct link to NullableBooleanCheck"></a></h3> Detects nullable boolean checks which use an elvis expression <code>?:</code> rather than equals <code>==</code>. Per the <a href="https://kotlinlang.org/docs/coding-conventions.html#nullable-boolean-values-in-conditions" target="_blank" rel="noopener noreferrer">Kotlin coding conventions</a> converting a nullable boolean property to non-null should be done via <code>!= false</code> or <code>== true</code> rather than <code>?: true</code> or <code>?: false</code> (respectively). Active by default: No Requires Type Resolution Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-32">Noncompliant Code:<a href="#noncompliant-code-32" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">value ?: true value ?: false </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-27">Compliant Code:<a href="#compliant-code-27" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">value != false value == true </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="objectliteraltolambda">ObjectLiteralToLambda<a href="#objectliteraltolambda" class="hash-link" aria-label="Direct link to ObjectLiteralToLambda" title="Direct link to ObjectLiteralToLambda"></a></h3> An anonymous object that does nothing other than the implementation of a single method can be used as a lambda. See <a href="https://kotlinlang.org/docs/java-interop.html#sam-conversions" target="_blank" rel="noopener noreferrer">SAM conversions</a>, <a href="https://kotlinlang.org/docs/fun-interfaces.html" target="_blank" rel="noopener noreferrer">Functional (SAM) interfaces</a> Active by default: Yes - Since v1.21.0 Requires Type Resolution Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-33">Noncompliant Code:<a href="#noncompliant-code-33" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">object : Foo { override fun bar() { } } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-28">Compliant Code:<a href="#compliant-code-28" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">Foo { } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="optionalabstractkeyword">OptionalAbstractKeyword<a href="#optionalabstractkeyword" class="hash-link" aria-label="Direct link to OptionalAbstractKeyword" title="Direct link to OptionalAbstractKeyword"></a></h3> This rule reports <code>abstract</code> modifiers which are unnecessary and can be removed. Active by default: Yes - Since v1.0.0 Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-34">Noncompliant Code:<a href="#noncompliant-code-34" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">abstract interface Foo { // abstract keyword not needed abstract fun x() // abstract keyword not needed abstract var y: Int // abstract keyword not needed } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-29">Compliant Code:<a href="#compliant-code-29" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">interface Foo { fun x() var y: Int } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="optionalunit">OptionalUnit<a href="#optionalunit" class="hash-link" aria-label="Direct link to OptionalUnit" title="Direct link to OptionalUnit"></a></h3> It is not necessary to define a return type of <code>Unit</code> on functions or to specify a lone Unit statement. This rule detects and reports instances where the <code>Unit</code> return type is specified on functions and the occurrences of a lone Unit statement. Active by default: No Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-35">Noncompliant Code:<a href="#noncompliant-code-35" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">fun foo(): Unit { return Unit } fun foo() = Unit fun doesNothing() { Unit } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-30">Compliant Code:<a href="#compliant-code-30" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">fun foo() { } // overridden no-op functions are allowed override fun foo() = Unit </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="optionalwhenbraces"><del>OptionalWhenBraces</del><a href="#optionalwhenbraces" class="hash-link" aria-label="Direct link to optionalwhenbraces" title="Direct link to optionalwhenbraces"></a></h3> Same functionality is implemented in BracesOnWhenStatements This rule reports unnecessary braces in when expressions. These optional braces should be removed. Active by default: No Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-36">Noncompliant Code:<a href="#noncompliant-code-36" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">val i = 1 when (i) { 1 -> { println("one") } // unnecessary curly braces since there is only one statement else -> println("else") } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-31">Compliant Code:<a href="#compliant-code-31" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">val i = 1 when (i) { 1 -> println("one") else -> println("else") } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="prefertooverpairsyntax">PreferToOverPairSyntax<a href="#prefertooverpairsyntax" class="hash-link" aria-label="Direct link to PreferToOverPairSyntax" title="Direct link to PreferToOverPairSyntax"></a></h3> This rule detects the usage of the Pair constructor to create pairs of values. Using <code><value1></code> to <code><value2></code> is preferred. Active by default: No Requires Type Resolution Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-37">Noncompliant Code:<a href="#noncompliant-code-37" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">val pair = Pair(1, 2) </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-32">Compliant Code:<a href="#compliant-code-32" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">val pair = 1 to 2 </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="protectedmemberinfinalclass">ProtectedMemberInFinalClass<a href="#protectedmemberinfinalclass" class="hash-link" aria-label="Direct link to ProtectedMemberInFinalClass" title="Direct link to ProtectedMemberInFinalClass"></a></h3> Kotlin classes are <code>final</code> by default. Thus classes which are not marked as <code>open</code> should not contain any <code>protected</code> members. Consider using <code>private</code> or <code>internal</code> modifiers instead. Active by default: Yes - Since v1.2.0 Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-38">Noncompliant Code:<a href="#noncompliant-code-38" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">class ProtectedMemberInFinalClass { protected var i = 0 } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-33">Compliant Code:<a href="#compliant-code-33" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">class ProtectedMemberInFinalClass { private var i = 0 } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="redundantexplicittype">RedundantExplicitType<a href="#redundantexplicittype" class="hash-link" aria-label="Direct link to RedundantExplicitType" title="Direct link to RedundantExplicitType"></a></h3> Local properties do not need their type to be explicitly provided when the inferred type matches the explicit type. Active by default: No Requires Type Resolution Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-39">Noncompliant Code:<a href="#noncompliant-code-39" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">fun function() { val x: String = "string" } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-34">Compliant Code:<a href="#compliant-code-34" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">fun function() { val x = "string" } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="redundanthigherordermapusage">RedundantHigherOrderMapUsage<a href="#redundanthigherordermapusage" class="hash-link" aria-label="Direct link to RedundantHigherOrderMapUsage" title="Direct link to RedundantHigherOrderMapUsage"></a></h3> Redundant maps add complexity to the code and accomplish nothing. They should be removed or replaced with the proper operator. Active by default: Yes - Since v1.21.0 Requires Type Resolution Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-40">Noncompliant Code:<a href="#noncompliant-code-40" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">fun foo(list: List<Int>): List<Int> { return list .filter { it > 5 } .map { it } } fun bar(list: List<Int>): List<Int> { return list .filter { it > 5 } .map { doSomething(it) it } } fun baz(set: Set<Int>): List<Int> { return set.map { it } } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-35">Compliant Code:<a href="#compliant-code-35" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">fun foo(list: List<Int>): List<Int> { return list .filter { it > 5 } } fun bar(list: List<Int>): List<Int> { return list .filter { it > 5 } .onEach { doSomething(it) } } fun baz(set: Set<Int>): List<Int> { return set.toList() } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="redundantvisibilitymodifierrule">RedundantVisibilityModifierRule<a href="#redundantvisibilitymodifierrule" class="hash-link" aria-label="Direct link to RedundantVisibilityModifierRule" title="Direct link to RedundantVisibilityModifierRule"></a></h3> This rule checks for redundant visibility modifiers. One exemption is the <a href="https://kotlinlang.org/docs/whatsnew14.html#explicit-api-mode-for-library-authors" target="_blank" rel="noopener noreferrer">explicit API mode</a> In this mode, the visibility modifier should be defined explicitly even if it is public. Hence, the rule ignores the visibility modifiers in explicit API mode. Active by default: No Debt: 5min Aliases: RedundantVisibilityModifier <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-41">Noncompliant Code:<a href="#noncompliant-code-41" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">public interface Foo { // public per default public fun bar() // public per default } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-36">Compliant Code:<a href="#compliant-code-36" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">interface Foo { fun bar() } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="returncount">ReturnCount<a href="#returncount" class="hash-link" aria-label="Direct link to ReturnCount" title="Direct link to ReturnCount"></a></h3> Restrict the number of return methods allowed in methods. Having many exit points in a function can be confusing and impacts readability of the code. Active by default: Yes - Since v1.0.0 Debt: 10min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="configuration-options-19">Configuration options:<a href="#configuration-options-19" class="hash-link" aria-label="Direct link to Configuration options:" title="Direct link to Configuration options:"></a></h4> <ul> <li> <code>max</code> (default: <code>2</code>) define the maximum number of return statements allowed per function </li> <li> <code>excludedFunctions</code> (default: <code>['equals']</code>) define a list of function names to be ignored by this check </li> <li> <code>excludeLabeled</code> (default: <code>false</code>) if labeled return statements should be ignored </li> <li> <code>excludeReturnFromLambda</code> (default: <code>true</code>) if labeled return from a lambda should be ignored </li> <li> <code>excludeGuardClauses</code> (default: <code>false</code>) if true guard clauses at the beginning of a method should be ignored </li> </ul> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-42">Noncompliant Code:<a href="#noncompliant-code-42" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">fun foo(i: Int): String { when (i) { 1 -> return "one" 2 -> return "two" else -> return "other" } } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-37">Compliant Code:<a href="#compliant-code-37" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">fun foo(i: Int): String { return when (i) { 1 -> "one" 2 -> "two" else -> "other" } } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="safecast">SafeCast<a href="#safecast" class="hash-link" aria-label="Direct link to SafeCast" title="Direct link to SafeCast"></a></h3> This rule inspects casts and reports casts which could be replaced with safe casts instead. Active by default: Yes - Since v1.0.0 Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-43">Noncompliant Code:<a href="#noncompliant-code-43" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">fun numberMagic(number: Number) { val i = if (number is Int) number else null // ... } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-38">Compliant Code:<a href="#compliant-code-38" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">fun numberMagic(number: Number) { val i = number as? Int // ... } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="serialversionuidinserializableclass">SerialVersionUIDInSerializableClass<a href="#serialversionuidinserializableclass" class="hash-link" aria-label="Direct link to SerialVersionUIDInSerializableClass" title="Direct link to SerialVersionUIDInSerializableClass"></a></h3> Classes which implement the <code>Serializable</code> interface should also correctly declare a <code>serialVersionUID</code>. This rule verifies that a <code>serialVersionUID</code> was correctly defined and declared as <code>private</code>. <a href="https://docs.oracle.com/javase/7/docs/api/java/io/Serializable.html" target="_blank" rel="noopener noreferrer">More about <code>SerialVersionUID</code></a> Active by default: Yes - Since v1.16.0 Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-44">Noncompliant Code:<a href="#noncompliant-code-44" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">class IncorrectSerializable : Serializable { companion object { val serialVersionUID = 1 // wrong declaration for UID } } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-39">Compliant Code:<a href="#compliant-code-39" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">class CorrectSerializable : Serializable { companion object { const val serialVersionUID = 1L } } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="spacingbetweenpackageandimports">SpacingBetweenPackageAndImports<a href="#spacingbetweenpackageandimports" class="hash-link" aria-label="Direct link to SpacingBetweenPackageAndImports" title="Direct link to SpacingBetweenPackageAndImports"></a></h3> This rule verifies spacing between package and import statements as well as between import statements and class declarations. Active by default: No Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-45">Noncompliant Code:<a href="#noncompliant-code-45" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">package foo import a.b class Bar { } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-40">Compliant Code:<a href="#compliant-code-40" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">package foo import a.b class Bar { } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="stringshouldberawstring">StringShouldBeRawString<a href="#stringshouldberawstring" class="hash-link" aria-label="Direct link to StringShouldBeRawString" title="Direct link to StringShouldBeRawString"></a></h3> This rule reports when the string can be converted to Kotlin raw string. Usage of a raw string is preferred as that avoids the need for escaping strings escape characters like \n, \t, ". Raw string also allows us to represent multiline string without the need of \n. Also, see <a href="https://kotlinlang.org/docs/coding-conventions.html#strings" target="_blank" rel="noopener noreferrer">Kotlin coding convention</a> for recommendation on using multiline strings Active by default: No Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="configuration-options-20">Configuration options:<a href="#configuration-options-20" class="hash-link" aria-label="Direct link to Configuration options:" title="Direct link to Configuration options:"></a></h4> <ul> <li> <code>maxEscapedCharacterCount</code> (default: <code>2</code>) maximum escape characters allowed </li> <li> <code>ignoredCharacters</code> (default: <code>[]</code>) list of characters to ignore </li> </ul> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-46">Noncompliant Code:<a href="#noncompliant-code-46" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">val windowJson = "{\n" + " \"window\": {\n" + " \"title\": \"Sample Quantum With AI and ML Widget\",\n" + " \"name\": \"main_window\",\n" + " \"width\": 500,\n" + " \"height\": 500\n" + " }\n" + "}" val patRegex = "/^(\\/[^\\/]+){0,2}\\/?\$/gm\n" </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-41">Compliant Code:<a href="#compliant-code-41" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">val windowJson = """ { "window": { "title": "Sample Quantum With AI and ML Widget", "name": "main_window", "width": 500, "height": 500 } } """.trimIndent() val patRegex = """/^(\/[^\/]+){0,2}\/?$/gm""" </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="throwscount">ThrowsCount<a href="#throwscount" class="hash-link" aria-label="Direct link to ThrowsCount" title="Direct link to ThrowsCount"></a></h3> Functions should have clear <code>throw</code> statements. Functions with many <code>throw</code> statements can be harder to read and lead to confusion. Instead, prefer limiting the number of <code>throw</code> statements in a function. Active by default: Yes - Since v1.0.0 Debt: 10min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="configuration-options-21">Configuration options:<a href="#configuration-options-21" class="hash-link" aria-label="Direct link to Configuration options:" title="Direct link to Configuration options:"></a></h4> <ul> <li> <code>max</code> (default: <code>2</code>) maximum amount of throw statements in a method </li> <li> <code>excludeGuardClauses</code> (default: <code>false</code>) if set to true, guard clauses do not count towards the allowed throws count </li> </ul> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-47">Noncompliant Code:<a href="#noncompliant-code-47" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">fun foo(i: Int) { when (i) { 1 -> throw IllegalArgumentException() 2 -> throw IllegalArgumentException() 3 -> throw IllegalArgumentException() } } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-42">Compliant Code:<a href="#compliant-code-42" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">fun foo(i: Int) { when (i) { 1,2,3 -> throw IllegalArgumentException() } } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="trailingwhitespace">TrailingWhitespace<a href="#trailingwhitespace" class="hash-link" aria-label="Direct link to TrailingWhitespace" title="Direct link to TrailingWhitespace"></a></h3> This rule reports lines that end with a whitespace. Active by default: No Debt: 5min <h3 class="anchor anchorWithStickyNavbar_LWe7" id="trimmultilinerawstring">TrimMultilineRawString<a href="#trimmultilinerawstring" class="hash-link" aria-label="Direct link to TrimMultilineRawString" title="Direct link to TrimMultilineRawString"></a></h3> All the Raw strings that have more than one line should be followed by <code>trimMargin()</code> or <code>trimIndent()</code>. Active by default: No Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="configuration-options-22">Configuration options:<a href="#configuration-options-22" class="hash-link" aria-label="Direct link to Configuration options:" title="Direct link to Configuration options:"></a></h4> <ul> <li> <code>trimmingMethods</code> (default: <code>['trimIndent', 'trimMargin']</code>) allows to provide a list of multiline string trimming methods </li> </ul> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-48">Noncompliant Code:<a href="#noncompliant-code-48" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">""" Hello World! How are you? """ </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-43">Compliant Code:<a href="#compliant-code-43" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">""" | Hello World! | How are you? """.trimMargin() """ Hello World! How are you? """.trimIndent() """Hello World! How are you?""" </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="underscoresinnumericliterals">UnderscoresInNumericLiterals<a href="#underscoresinnumericliterals" class="hash-link" aria-label="Direct link to UnderscoresInNumericLiterals" title="Direct link to UnderscoresInNumericLiterals"></a></h3> This rule detects and reports long base 10 numbers which should be separated with underscores for readability. For <code>Serializable</code> classes or objects, the field <code>serialVersionUID</code> is explicitly ignored. For floats and doubles, anything to the right of the decimal point is ignored. Active by default: No Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="configuration-options-23">Configuration options:<a href="#configuration-options-23" class="hash-link" aria-label="Direct link to Configuration options:" title="Direct link to Configuration options:"></a></h4> <ul> <li> <del><code>acceptableDecimalLength</code></del> (default: <code>5</code>) Deprecated: Use <code>acceptableLength</code> instead Length under which base 10 numbers are not required to have underscores </li> <li> <code>acceptableLength</code> (default: <code>4</code>) Maximum number of consecutive digits that a numeric literal can have without using an underscore </li> <li> <code>allowNonStandardGrouping</code> (default: <code>false</code>) If set to false, groups of exactly three digits must be used. If set to true, 100_00 is allowed. </li> </ul> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-49">Noncompliant Code:<a href="#noncompliant-code-49" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">const val DEFAULT_AMOUNT = 1000000 </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-44">Compliant Code:<a href="#compliant-code-44" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">const val DEFAULT_AMOUNT = 1_000_000 </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="unnecessaryabstractclass">UnnecessaryAbstractClass<a href="#unnecessaryabstractclass" class="hash-link" aria-label="Direct link to UnnecessaryAbstractClass" title="Direct link to UnnecessaryAbstractClass"></a></h3> This rule inspects <code>abstract</code> classes. In case an <code>abstract class</code> does not have any concrete members it should be refactored into an interface. Abstract classes which do not define any <code>abstract</code> members should instead be refactored into concrete classes. Active by default: Yes - Since v1.2.0 Requires Type Resolution Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="configuration-options-24">Configuration options:<a href="#configuration-options-24" class="hash-link" aria-label="Direct link to Configuration options:" title="Direct link to Configuration options:"></a></h4> <ul> <li> <del><code>excludeAnnotatedClasses</code></del> (default: <code>[]</code>) Deprecated: Use <code>ignoreAnnotated</code> instead Allows you to provide a list of annotations that disable this check. </li> </ul> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-50">Noncompliant Code:<a href="#noncompliant-code-50" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">abstract class OnlyAbstractMembersInAbstractClass { // violation: no concrete members abstract val i: Int abstract fun f() } abstract class OnlyConcreteMembersInAbstractClass { // violation: no abstract members val i: Int = 0 fun f() { } } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-45">Compliant Code:<a href="#compliant-code-45" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">interface OnlyAbstractMembersInInterface { val i: Int fun f() } class OnlyConcreteMembersInClass { val i: Int = 0 fun f() { } } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="unnecessaryannotationusesitetarget">UnnecessaryAnnotationUseSiteTarget<a href="#unnecessaryannotationusesitetarget" class="hash-link" aria-label="Direct link to UnnecessaryAnnotationUseSiteTarget" title="Direct link to UnnecessaryAnnotationUseSiteTarget"></a></h3> This rule inspects the use of the Annotation use-site Target. In case that the use-site Target is not needed it can be removed. For more information check the kotlin documentation: <a href="https://kotlinlang.org/docs/annotations.html#annotation-use-site-targets" target="_blank" rel="noopener noreferrer">Annotation use-site targets</a> Active by default: No Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-51">Noncompliant Code:<a href="#noncompliant-code-51" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">@property:Inject private val foo: String = "bar" // violation: unnecessary @property: class Module(@param:Inject private val foo: String) // violation: unnecessary @param: </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-46">Compliant Code:<a href="#compliant-code-46" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">class Module(@Inject private val foo: String) </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="unnecessaryapply">UnnecessaryApply<a href="#unnecessaryapply" class="hash-link" aria-label="Direct link to UnnecessaryApply" title="Direct link to UnnecessaryApply"></a></h3> <code>apply</code> expressions are used frequently, but sometimes their usage should be replaced with an ordinary method/extension function call to reduce visual complexity Active by default: Yes - Since v1.16.0 Requires Type Resolution Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-52">Noncompliant Code:<a href="#noncompliant-code-52" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">config.apply { version = "1.2" } // can be replaced with `config.version = "1.2"` config?.apply { environment = "test" } // can be replaced with `config?.environment = "test"` config?.apply { println(version) } // `apply` can be replaced by `let` </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-47">Compliant Code:<a href="#compliant-code-47" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">config.apply { version = "1.2" environment = "test" } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="unnecessarybackticks">UnnecessaryBackticks<a href="#unnecessarybackticks" class="hash-link" aria-label="Direct link to UnnecessaryBackticks" title="Direct link to UnnecessaryBackticks"></a></h3> This rule reports unnecessary backticks. Active by default: No Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-53">Noncompliant Code:<a href="#noncompliant-code-53" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">class `HelloWorld` </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-48">Compliant Code:<a href="#compliant-code-48" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">class HelloWorld </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="unnecessarybracesaroundtrailinglambda">UnnecessaryBracesAroundTrailingLambda<a href="#unnecessarybracesaroundtrailinglambda" class="hash-link" aria-label="Direct link to UnnecessaryBracesAroundTrailingLambda" title="Direct link to UnnecessaryBracesAroundTrailingLambda"></a></h3> In Kotlin functions the last lambda parameter of a function is a function then a lambda expression passed as the corresponding argument can be placed outside the parentheses. see <a href="https://kotlinlang.org/docs/lambdas.html#passing-trailing-lambdas" target="_blank" rel="noopener noreferrer">Passing trailing lambdas</a>. Prefer the usage of trailing lambda. Active by default: No Requires Type Resolution Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-54">Noncompliant Code:<a href="#noncompliant-code-54" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">fun test() { repeat(10, { println(it) }) } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-49">Compliant Code:<a href="#compliant-code-49" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">fun test() { repeat(10) { println(it) } } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="unnecessaryfilter">UnnecessaryFilter<a href="#unnecessaryfilter" class="hash-link" aria-label="Direct link to UnnecessaryFilter" title="Direct link to UnnecessaryFilter"></a></h3> Unnecessary filters add complexity to the code and accomplish nothing. They should be removed. Active by default: Yes - Since v1.21.0 Requires Type Resolution Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-55">Noncompliant Code:<a href="#noncompliant-code-55" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">val x = listOf(1, 2, 3) .filter { it > 1 } .count() val x = listOf(1, 2, 3) .filter { it > 1 } .isEmpty() </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-50">Compliant Code:<a href="#compliant-code-50" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">val x = listOf(1, 2, 3) .count { it > 2 } } val x = listOf(1, 2, 3) .none { it > 1 } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="unnecessaryinheritance">UnnecessaryInheritance<a href="#unnecessaryinheritance" class="hash-link" aria-label="Direct link to UnnecessaryInheritance" title="Direct link to UnnecessaryInheritance"></a></h3> This rule reports unnecessary super types. Inheriting from <code>Any</code> or <code>Object</code> is unnecessary and should simply be removed. Active by default: Yes - Since v1.2.0 Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-56">Noncompliant Code:<a href="#noncompliant-code-56" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">class A : Any() class B : Object() </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="unnecessaryinnerclass">UnnecessaryInnerClass<a href="#unnecessaryinnerclass" class="hash-link" aria-label="Direct link to UnnecessaryInnerClass" title="Direct link to UnnecessaryInnerClass"></a></h3> This rule reports unnecessary inner classes. Nested classes that do not access members from the outer class do not require the <code>inner</code> qualifier. Active by default: No Requires Type Resolution Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-57">Noncompliant Code:<a href="#noncompliant-code-57" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">class A { val foo = "BAR" inner class B { val fizz = "BUZZ" fun printFizz() { println(fizz) } } } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="unnecessarylet">UnnecessaryLet<a href="#unnecessarylet" class="hash-link" aria-label="Direct link to UnnecessaryLet" title="Direct link to UnnecessaryLet"></a></h3> <code>let</code> expressions are used extensively in our code for null-checking and chaining functions, but sometimes their usage should be replaced with an ordinary method/extension function call to reduce visual complexity. Active by default: No Requires Type Resolution Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-58">Noncompliant Code:<a href="#noncompliant-code-58" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">a.let { print(it) } // can be replaced with `print(a)` a.let { it.plus(1) } // can be replaced with `a.plus(1)` a?.let { it.plus(1) } // can be replaced with `a?.plus(1)` a?.let { that -> that.plus(1) }?.let { it.plus(1) } // can be replaced with `a?.plus(1)?.plus(1)` a.let { 1.plus(1) } // can be replaced with `1.plus(1)` a?.let { 1.plus(1) } // can be replaced with `if (a != null) 1.plus(1)` </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-51">Compliant Code:<a href="#compliant-code-51" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">a?.let { print(it) } a?.let { 1.plus(it) } ?.let { msg -> print(msg) } a?.let { it.plus(it) } val b = a?.let { 1.plus(1) } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="unnecessaryparentheses">UnnecessaryParentheses<a href="#unnecessaryparentheses" class="hash-link" aria-label="Direct link to UnnecessaryParentheses" title="Direct link to UnnecessaryParentheses"></a></h3> This rule reports unnecessary parentheses around expressions. These unnecessary parentheses can safely be removed. Added in v1.0.0.RC4 Active by default: No Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="configuration-options-25">Configuration options:<a href="#configuration-options-25" class="hash-link" aria-label="Direct link to Configuration options:" title="Direct link to Configuration options:"></a></h4> <ul> <li> <code>allowForUnclearPrecedence</code> (default: <code>false</code>) allow parentheses when not strictly required but precedence may be unclear, such as <code>(a && b) || c</code> </li> </ul> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-59">Noncompliant Code:<a href="#noncompliant-code-59" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">val local = (5 + 3) if ((local == 8)) { } fun foo() { function({ input -> println(input) }) } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-52">Compliant Code:<a href="#compliant-code-52" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">val local = 5 + 3 if (local == 8) { } fun foo() { function { input -> println(input) } } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="untilinsteadofrangeto">UntilInsteadOfRangeTo<a href="#untilinsteadofrangeto" class="hash-link" aria-label="Direct link to UntilInsteadOfRangeTo" title="Direct link to UntilInsteadOfRangeTo"></a></h3> Reports calls to '..' operator instead of calls to 'until'. 'until' is applicable in cases where the upper range value is described as some value subtracted by 1. 'until' helps to prevent off-by-one errors. Active by default: No Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-60">Noncompliant Code:<a href="#noncompliant-code-60" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">for (i in 0 .. 10 - 1) {} val range = 0 .. 10 - 1 </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-53">Compliant Code:<a href="#compliant-code-53" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">for (i in 0 until 10) {} val range = 0 until 10 </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="unusedimports">UnusedImports<a href="#unusedimports" class="hash-link" aria-label="Direct link to UnusedImports" title="Direct link to UnusedImports"></a></h3> This rule reports unused imports. Unused imports are dead code and should be removed. Exempt from this rule are imports resulting from references to elements within KDoc and from destructuring declarations (componentN imports). Active by default: No Debt: 5min <h3 class="anchor anchorWithStickyNavbar_LWe7" id="unusedparameter">UnusedParameter<a href="#unusedparameter" class="hash-link" aria-label="Direct link to UnusedParameter" title="Direct link to UnusedParameter"></a></h3> An unused parameter can be removed to simplify the signature of the function. Active by default: Yes - Since v1.23.0 Debt: 5min Aliases: UNUSED_VARIABLE, UNUSED_PARAMETER, unused, UnusedPrivateMember <h4 class="anchor anchorWithStickyNavbar_LWe7" id="configuration-options-26">Configuration options:<a href="#configuration-options-26" class="hash-link" aria-label="Direct link to Configuration options:" title="Direct link to Configuration options:"></a></h4> <ul> <li> <code>allowedNames</code> (default: <code>'ignored|expected'</code>) unused parameter names matching this regex are ignored </li> </ul> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-61">Noncompliant Code:<a href="#noncompliant-code-61" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">fun foo(unused: String) { println() } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-54">Compliant Code:<a href="#compliant-code-54" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">fun foo(used: String) { println(used) } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="unusedprivateclass">UnusedPrivateClass<a href="#unusedprivateclass" class="hash-link" aria-label="Direct link to UnusedPrivateClass" title="Direct link to UnusedPrivateClass"></a></h3> Reports unused private classes. If private classes are unused they should be removed. Otherwise, this dead code can lead to confusion and potential bugs. Active by default: Yes - Since v1.2.0 Debt: 5min Aliases: unused <h3 class="anchor anchorWithStickyNavbar_LWe7" id="unusedprivatemember">UnusedPrivateMember<a href="#unusedprivatemember" class="hash-link" aria-label="Direct link to UnusedPrivateMember" title="Direct link to UnusedPrivateMember"></a></h3> Reports unused private functions. If these private functions are unused they should be removed. Otherwise, this dead code can lead to confusion and potential bugs. Active by default: Yes - Since v1.16.0 Debt: 5min Aliases: UNUSED_VARIABLE, UNUSED_PARAMETER, unused <h4 class="anchor anchorWithStickyNavbar_LWe7" id="configuration-options-27">Configuration options:<a href="#configuration-options-27" class="hash-link" aria-label="Direct link to Configuration options:" title="Direct link to Configuration options:"></a></h4> <ul> <li> <code>allowedNames</code> (default: <code>''</code>) unused private function names matching this regex are ignored </li> </ul> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="unusedprivateproperty">UnusedPrivateProperty<a href="#unusedprivateproperty" class="hash-link" aria-label="Direct link to UnusedPrivateProperty" title="Direct link to UnusedPrivateProperty"></a></h3> An unused private property can be removed to simplify the source file. This rule also detects unused constructor parameters since these can become properties of the class when they are declared with <code>val</code> or <code>var</code>. Active by default: Yes - Since v1.23.0 Debt: 5min Aliases: UNUSED_VARIABLE, UNUSED_PARAMETER, unused, UnusedPrivateMember <h4 class="anchor anchorWithStickyNavbar_LWe7" id="configuration-options-28">Configuration options:<a href="#configuration-options-28" class="hash-link" aria-label="Direct link to Configuration options:" title="Direct link to Configuration options:"></a></h4> <ul> <li> <code>allowedNames</code> (default: <code>'_|ignored|expected|serialVersionUID'</code>) unused property names matching this regex are ignored </li> </ul> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-62">Noncompliant Code:<a href="#noncompliant-code-62" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">class Foo { private val unused = "unused" } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-55">Compliant Code:<a href="#compliant-code-55" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">class Foo { private val used = "used" fun greet() { println(used) } } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="useanyornoneinsteadoffind">UseAnyOrNoneInsteadOfFind<a href="#useanyornoneinsteadoffind" class="hash-link" aria-label="Direct link to UseAnyOrNoneInsteadOfFind" title="Direct link to UseAnyOrNoneInsteadOfFind"></a></h3> Turn on this rule to flag <code>find</code> calls for null check that can be replaced with a <code>any</code> or <code>none</code> call. Active by default: Yes - Since v1.21.0 Requires Type Resolution Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-63">Noncompliant Code:<a href="#noncompliant-code-63" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">listOf(1, 2, 3).find { it == 4 } != null listOf(1, 2, 3).find { it == 4 } == null </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-56">Compliant Code:<a href="#compliant-code-56" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">listOf(1, 2, 3).any { it == 4 } listOf(1, 2, 3).none { it == 4 } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="usearrayliteralsinannotations">UseArrayLiteralsInAnnotations<a href="#usearrayliteralsinannotations" class="hash-link" aria-label="Direct link to UseArrayLiteralsInAnnotations" title="Direct link to UseArrayLiteralsInAnnotations"></a></h3> This rule detects annotations which use the arrayOf(...) syntax instead of the array literal [...] syntax. The latter should be preferred as it is more readable. Active by default: Yes - Since v1.21.0 Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-64">Noncompliant Code:<a href="#noncompliant-code-64" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">@PositiveCase(arrayOf("...")) </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-57">Compliant Code:<a href="#compliant-code-57" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">@NegativeCase(["..."]) </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="usechecknotnull">UseCheckNotNull<a href="#usechecknotnull" class="hash-link" aria-label="Direct link to UseCheckNotNull" title="Direct link to UseCheckNotNull"></a></h3> Turn on this rule to flag <code>check</code> calls for not-null check that can be replaced with a <code>checkNotNull</code> call. Active by default: Yes - Since v1.21.0 Requires Type Resolution Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-65">Noncompliant Code:<a href="#noncompliant-code-65" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">check(x != null) </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-58">Compliant Code:<a href="#compliant-code-58" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">checkNotNull(x) </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="usecheckorerror">UseCheckOrError<a href="#usecheckorerror" class="hash-link" aria-label="Direct link to UseCheckOrError" title="Direct link to UseCheckOrError"></a></h3> Kotlin provides a concise way to check invariants as well as pre- and post-conditions. Prefer them instead of manually throwing an IllegalStateException. Active by default: Yes - Since v1.21.0 Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-66">Noncompliant Code:<a href="#noncompliant-code-66" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">if (value == null) throw IllegalStateException("value should not be null") if (value < 0) throw IllegalStateException("value is $value but should be at least 0") when(a) { 1 -> doSomething() else -> throw IllegalStateException("Unexpected value") } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-59">Compliant Code:<a href="#compliant-code-59" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">checkNotNull(value) { "value should not be null" } check(value >= 0) { "value is $value but should be at least 0" } when(a) { 1 -> doSomething() else -> error("Unexpected value") } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="usedataclass">UseDataClass<a href="#usedataclass" class="hash-link" aria-label="Direct link to UseDataClass" title="Direct link to UseDataClass"></a></h3> Classes that simply hold data should be refactored into a <code>data class</code>. Data classes are specialized to hold data and generate <code>hashCode</code>, <code>equals</code> and <code>toString</code> implementations as well. Read more about <a href="https://kotlinlang.org/docs/data-classes.html" target="_blank" rel="noopener noreferrer">data classes</a> Active by default: No Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="configuration-options-29">Configuration options:<a href="#configuration-options-29" class="hash-link" aria-label="Direct link to Configuration options:" title="Direct link to Configuration options:"></a></h4> <ul> <li> <del><code>excludeAnnotatedClasses</code></del> (default: <code>[]</code>) Deprecated: Use <code>ignoreAnnotated</code> instead allows to provide a list of annotations that disable this check </li> <li> <code>allowVars</code> (default: <code>false</code>) allows to relax this rule in order to exclude classes that contains one (or more) vars </li> </ul> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-67">Noncompliant Code:<a href="#noncompliant-code-67" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">class DataClassCandidate(val i: Int) { val i2: Int = 0 } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-60">Compliant Code:<a href="#compliant-code-60" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">data class DataClass(val i: Int, val i2: Int) // classes with delegating interfaces are compliant interface I class B() : I class A(val b: B) : I by b </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="useemptycounterpart">UseEmptyCounterpart<a href="#useemptycounterpart" class="hash-link" aria-label="Direct link to UseEmptyCounterpart" title="Direct link to UseEmptyCounterpart"></a></h3> Instantiation of an object's "empty" state should use the object's "empty" initializer for clarity purposes. Active by default: No Requires Type Resolution Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-68">Noncompliant Code:<a href="#noncompliant-code-68" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">arrayOf() listOf() // or listOfNotNull() mapOf() sequenceOf() setOf() </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-61">Compliant Code:<a href="#compliant-code-61" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">emptyArray() emptyList() emptyMap() emptySequence() emptySet() </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="useifemptyorifblank">UseIfEmptyOrIfBlank<a href="#useifemptyorifblank" class="hash-link" aria-label="Direct link to UseIfEmptyOrIfBlank" title="Direct link to UseIfEmptyOrIfBlank"></a></h3> This rule detects <code>isEmpty</code> or <code>isBlank</code> calls to assign a default value. They can be replaced with <code>ifEmpty</code> or <code>ifBlank</code> calls. Active by default: No Requires Type Resolution Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-69">Noncompliant Code:<a href="#noncompliant-code-69" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">fun test(list: List<Int>, s: String) { val a = if (list.isEmpty()) listOf(1) else list val b = if (list.isNotEmpty()) list else listOf(2) val c = if (s.isBlank()) "foo" else s val d = if (s.isNotBlank()) s else "bar" } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-62">Compliant Code:<a href="#compliant-code-62" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">fun test(list: List<Int>, s: String) { val a = list.ifEmpty { listOf(1) } val b = list.ifEmpty { listOf(2) } val c = s.ifBlank { "foo" } val d = s.ifBlank { "bar" } } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="useifinsteadofwhen">UseIfInsteadOfWhen<a href="#useifinsteadofwhen" class="hash-link" aria-label="Direct link to UseIfInsteadOfWhen" title="Direct link to UseIfInsteadOfWhen"></a></h3> Binary expressions are better expressed using an <code>if</code> expression than a <code>when</code> expression. See <a href="https://kotlinlang.org/docs/coding-conventions.html#if-versus-when" target="_blank" rel="noopener noreferrer">if versus when</a> Active by default: No Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="configuration-options-30">Configuration options:<a href="#configuration-options-30" class="hash-link" aria-label="Direct link to Configuration options:" title="Direct link to Configuration options:"></a></h4> <ul> <li> <code>ignoreWhenContainingVariableDeclaration</code> (default: <code>false</code>) ignores when statements with a variable declaration used in the subject </li> </ul> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-70">Noncompliant Code:<a href="#noncompliant-code-70" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">when (x) { null -> true else -> false } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-63">Compliant Code:<a href="#compliant-code-63" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">if (x == null) true else false </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="useisnullorempty">UseIsNullOrEmpty<a href="#useisnullorempty" class="hash-link" aria-label="Direct link to UseIsNullOrEmpty" title="Direct link to UseIsNullOrEmpty"></a></h3> This rule detects null or empty checks that can be replaced with <code>isNullOrEmpty()</code> call. Active by default: Yes - Since v1.21.0 Requires Type Resolution Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-71">Noncompliant Code:<a href="#noncompliant-code-71" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">fun foo(x: List<Int>?) { if (x == null || x.isEmpty()) return } fun bar(x: List<Int>?) { if (x == null || x.count() == 0) return } fun baz(x: List<Int>?) { if (x == null || x.size == 0) return } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-64">Compliant Code:<a href="#compliant-code-64" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">if (x.isNullOrEmpty()) return </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="uselet">UseLet<a href="#uselet" class="hash-link" aria-label="Direct link to UseLet" title="Direct link to UseLet"></a></h3> <code>if</code> expressions that either check for not-null and return <code>null</code> in the false case or check for <code>null</code> and returns <code>null</code> in the truthy case are better represented as <code>?.let {}</code> blocks. Active by default: No Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-72">Noncompliant Code:<a href="#noncompliant-code-72" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">if (x != null) { x.transform() } else null if (x == null) null else y </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-65">Compliant Code:<a href="#compliant-code-65" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">x?.let { it.transform() } x?.let { y } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="useorempty">UseOrEmpty<a href="#useorempty" class="hash-link" aria-label="Direct link to UseOrEmpty" title="Direct link to UseOrEmpty"></a></h3> This rule detects <code>?: emptyList()</code> that can be replaced with <code>orEmpty()</code> call. Active by default: Yes - Since v1.21.0 Requires Type Resolution Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-73">Noncompliant Code:<a href="#noncompliant-code-73" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">fun test(x: List<Int>?, s: String?) { val a = x ?: emptyList() val b = s ?: "" } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-66">Compliant Code:<a href="#compliant-code-66" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">fun test(x: List<Int>?, s: String?) { val a = x.orEmpty() val b = s.orEmpty() } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="userequire">UseRequire<a href="#userequire" class="hash-link" aria-label="Direct link to UseRequire" title="Direct link to UseRequire"></a></h3> Kotlin provides a much more concise way to check preconditions than to manually throw an IllegalArgumentException. Active by default: Yes - Since v1.21.0 Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-74">Noncompliant Code:<a href="#noncompliant-code-74" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">if (value == null) throw IllegalArgumentException("value should not be null") if (value < 0) throw IllegalArgumentException("value is $value but should be at least 0") </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-67">Compliant Code:<a href="#compliant-code-67" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">requireNotNull(value) { "value should not be null" } require(value >= 0) { "value is $value but should be at least 0" } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="userequirenotnull">UseRequireNotNull<a href="#userequirenotnull" class="hash-link" aria-label="Direct link to UseRequireNotNull" title="Direct link to UseRequireNotNull"></a></h3> Turn on this rule to flag <code>require</code> calls for not-null check that can be replaced with a <code>requireNotNull</code> call. Active by default: Yes - Since v1.21.0 Requires Type Resolution Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-75">Noncompliant Code:<a href="#noncompliant-code-75" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">require(x != null) </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-68">Compliant Code:<a href="#compliant-code-68" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">requireNotNull(x) </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="usesumofinsteadofflatmapsize">UseSumOfInsteadOfFlatMapSize<a href="#usesumofinsteadofflatmapsize" class="hash-link" aria-label="Direct link to UseSumOfInsteadOfFlatMapSize" title="Direct link to UseSumOfInsteadOfFlatMapSize"></a></h3> Turn on this rule to flag <code>flatMap</code> and <code>size/count</code> calls that can be replaced with a <code>sumOf</code> call. Active by default: No Requires Type Resolution Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-76">Noncompliant Code:<a href="#noncompliant-code-76" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">class Foo(val foo: List<Int>) list.flatMap { it.foo }.size list.flatMap { it.foo }.count() list.flatMap { it.foo }.count { it > 2 } listOf(listOf(1), listOf(2, 3)).flatten().size </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-69">Compliant Code:<a href="#compliant-code-69" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">list.sumOf { it.foo.size } list.sumOf { it.foo.count() } list.sumOf { it.foo.count { foo -> foo > 2 } } listOf(listOf(1), listOf(2, 3)).sumOf { it.size } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="uselesscallonnotnull">UselessCallOnNotNull<a href="#uselesscallonnotnull" class="hash-link" aria-label="Direct link to UselessCallOnNotNull" title="Direct link to UselessCallOnNotNull"></a></h3> The Kotlin stdlib provides some functions that are designed to operate on references that may be null. These functions can also be called on non-nullable references or on collections or sequences that are known to be empty - the calls are redundant in this case and can be removed or should be changed to a call that does not check whether the value is null or not. Active by default: Yes - Since v1.2.0 Requires Type Resolution Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-77">Noncompliant Code:<a href="#noncompliant-code-77" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">val testList = listOf("string").orEmpty() val testList2 = listOf("string").orEmpty().map { _ } val testList3 = listOfNotNull("string") val testString = ""?.isNullOrBlank() </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-70">Compliant Code:<a href="#compliant-code-70" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">val testList = listOf("string") val testList2 = listOf("string").map { } val testList3 = listOf("string") val testString = ""?.isBlank() </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="utilityclasswithpublicconstructor">UtilityClassWithPublicConstructor<a href="#utilityclasswithpublicconstructor" class="hash-link" aria-label="Direct link to UtilityClassWithPublicConstructor" title="Direct link to UtilityClassWithPublicConstructor"></a></h3> A class which only contains utility variables and functions with no concrete implementation can be refactored into an <code>object</code> or a class with a non-public constructor. Furthermore, this rule reports utility classes which are not final. Active by default: Yes - Since v1.2.0 Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-78">Noncompliant Code:<a href="#noncompliant-code-78" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">class UtilityClassViolation { // public constructor here constructor() { // ... } companion object { val i = 0 } } open class UtilityClassViolation private constructor() { // ... } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-71">Compliant Code:<a href="#compliant-code-71" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">class UtilityClass { private constructor() { // ... } companion object { val i = 0 } } object UtilityClass { val i = 0 } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="varcouldbeval">VarCouldBeVal<a href="#varcouldbeval" class="hash-link" aria-label="Direct link to VarCouldBeVal" title="Direct link to VarCouldBeVal"></a></h3> Reports var declarations (both local variables and private class properties) that could be val, as they are not re-assigned. Val declarations are assign-once (read-only), which makes understanding the current state easier. Active by default: Yes - Since v1.16.0 Requires Type Resolution Debt: 5min Aliases: CanBeVal <h4 class="anchor anchorWithStickyNavbar_LWe7" id="configuration-options-31">Configuration options:<a href="#configuration-options-31" class="hash-link" aria-label="Direct link to Configuration options:" title="Direct link to Configuration options:"></a></h4> <ul> <li> <code>ignoreLateinitVar</code> (default: <code>false</code>) Whether to ignore uninitialized lateinit vars </li> </ul> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-79">Noncompliant Code:<a href="#noncompliant-code-79" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">fun example() { var i = 1 // violation: this variable is never re-assigned val j = i + 1 } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-72">Compliant Code:<a href="#compliant-code-72" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">fun example() { val i = 1 val j = i + 1 } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h3 class="anchor anchorWithStickyNavbar_LWe7" id="wildcardimport">WildcardImport<a href="#wildcardimport" class="hash-link" aria-label="Direct link to WildcardImport" title="Direct link to WildcardImport"></a></h3> Wildcard imports should be replaced with imports using fully qualified class names. This helps increase clarity of which classes are imported and helps prevent naming conflicts. Library updates can introduce naming clashes with your own classes which might result in compilation errors. NOTE: This rule has a twin implementation NoWildcardImports in the formatting rule set (a wrapped KtLint rule). When suppressing an issue of WildcardImport in the baseline file, make sure to suppress the corresponding NoWildcardImports issue. Active by default: Yes - Since v1.0.0 Debt: 5min <h4 class="anchor anchorWithStickyNavbar_LWe7" id="configuration-options-32">Configuration options:<a href="#configuration-options-32" class="hash-link" aria-label="Direct link to Configuration options:" title="Direct link to Configuration options:"></a></h4> <ul> <li> <code>excludeImports</code> (default: <code>['java.util.*']</code>) Define a list of package names that should be allowed to be imported with wildcard imports. </li> </ul> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="noncompliant-code-80">Noncompliant Code:<a href="#noncompliant-code-80" class="hash-link" aria-label="Direct link to Noncompliant Code:" title="Direct link to Noncompliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">import io.gitlab.arturbosch.detekt.* class DetektElements { val element1 = DetektElement1() val element2 = DetektElement2() } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" d="M21,7L9,19L3.5,13.5L4.91,12.09L9,16.17L19.59,5.59L21,7Z"></path></svg></button></div></div></div> <h4 class="anchor anchorWithStickyNavbar_LWe7" id="compliant-code-73">Compliant Code:<a href="#compliant-code-73" class="hash-link" aria-label="Direct link to Compliant Code:" title="Direct link to Compliant Code:"></a></h4> <div class="language-kotlin codeBlockContainer_Ckt0 theme-code-block" style="--prism-color:#393A34;--prism-background-color:#f6f8fa"><div class="codeBlockContent_biex"><pre tabindex="0" class="prism-code language-kotlin codeBlock_bY9V thin-scrollbar" style="color:#393A34;background-color:#f6f8fa"><code class="codeBlockLines_e6Vv">import io.gitlab.arturbosch.detekt.DetektElement1 import io.gitlab.arturbosch.detekt.DetektElement2 class DetektElements { val element1 = DetektElement1() val element2 = DetektElement2() } </code></pre><div class="buttonGroup__atx"><button type="button" aria-label="Copy code to clipboard" title="Copy" class="clean-btn"><svg viewBox="0 0 24 24" class="copyButtonIcon_y97N"><path fill="currentColor" d="M19,21H8V7H19M19,5H8A2,2 0 0,0 6,7V21A2,2 0 0,0 8,23H19A2,2 0 0,0 21,21V7A2,2 0 0,0 19,5M16,1H4A2,2 0 0,0 2,3V17H4V3H16V1Z"></path></svg><svg viewBox="0 0 24 24" class="copyButtonSuccessIcon_LjdS"><path fill="currentColor" 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class="pagination-nav__label">Ruleauthors Rule Set</div></a></nav></div></div><div class="col col--3"><div class="tableOfContents_bqdL thin-scrollbar theme-doc-toc-desktop"><ul class="table-of-contents table-of-contents__left-border"><li><a href="#alsocouldbeapply" class="table-of-contents__link toc-highlight">AlsoCouldBeApply</a></li><li><a href="#bracesonifstatements" class="table-of-contents__link toc-highlight">BracesOnIfStatements</a></li><li><a href="#bracesonwhenstatements" class="table-of-contents__link toc-highlight">BracesOnWhenStatements</a></li><li><a href="#canbenonnullable" class="table-of-contents__link toc-highlight">CanBeNonNullable</a></li><li><a href="#cascadingcallwrapping" class="table-of-contents__link toc-highlight">CascadingCallWrapping</a></li><li><a href="#classordering" class="table-of-contents__link toc-highlight">ClassOrdering</a></li><li><a href="#collapsibleifstatements" class="table-of-contents__link toc-highlight">CollapsibleIfStatements</a></li><li><a href="#dataclasscontainsfunctions" class="table-of-contents__link toc-highlight">DataClassContainsFunctions</a></li><li><a href="#dataclassshouldbeimmutable" class="table-of-contents__link toc-highlight">DataClassShouldBeImmutable</a></li><li><a href="#destructuringdeclarationwithtoomanyentries" class="table-of-contents__link toc-highlight">DestructuringDeclarationWithTooManyEntries</a></li><li><a href="#doublenegativelambda" class="table-of-contents__link toc-highlight">DoubleNegativeLambda</a></li><li><a href="#equalsnullcall" class="table-of-contents__link toc-highlight">EqualsNullCall</a></li><li><a href="#equalsonsignatureline" class="table-of-contents__link toc-highlight">EqualsOnSignatureLine</a></li><li><a href="#explicitcollectionelementaccessmethod" class="table-of-contents__link toc-highlight">ExplicitCollectionElementAccessMethod</a></li><li><a href="#explicititlambdaparameter" class="table-of-contents__link toc-highlight">ExplicitItLambdaParameter</a></li><li><a href="#expressionbodysyntax" class="table-of-contents__link toc-highlight">ExpressionBodySyntax</a></li><li><a href="#forbiddenannotation" class="table-of-contents__link toc-highlight">ForbiddenAnnotation</a></li><li><a href="#forbiddencomment" class="table-of-contents__link toc-highlight">ForbiddenComment</a></li><li><a href="#forbiddenimport" class="table-of-contents__link toc-highlight">ForbiddenImport</a></li><li><a href="#forbiddenmethodcall" class="table-of-contents__link toc-highlight">ForbiddenMethodCall</a></li><li><a href="#forbiddensuppress" class="table-of-contents__link toc-highlight">ForbiddenSuppress</a></li><li><a href="#forbiddenvoid" class="table-of-contents__link toc-highlight">ForbiddenVoid</a></li><li><a href="#functiononlyreturningconstant" class="table-of-contents__link toc-highlight">FunctionOnlyReturningConstant</a></li><li><a href="#loopwithtoomanyjumpstatements" class="table-of-contents__link toc-highlight">LoopWithTooManyJumpStatements</a></li><li><a href="#magicnumber" class="table-of-contents__link toc-highlight">MagicNumber</a></li><li><a href="#mandatorybracesloops" class="table-of-contents__link toc-highlight">MandatoryBracesLoops</a></li><li><a href="#maxchainedcallsonsameline" class="table-of-contents__link toc-highlight">MaxChainedCallsOnSameLine</a></li><li><a href="#maxlinelength" class="table-of-contents__link toc-highlight">MaxLineLength</a></li><li><a href="#maybeconst" class="table-of-contents__link toc-highlight">MayBeConst</a></li><li><a href="#modifierorder" class="table-of-contents__link toc-highlight">ModifierOrder</a></li><li><a href="#multilinelambdaitparameter" class="table-of-contents__link toc-highlight">MultilineLambdaItParameter</a></li><li><a href="#multilinerawstringindentation" class="table-of-contents__link toc-highlight">MultilineRawStringIndentation</a></li><li><a href="#nestedclassesvisibility" class="table-of-contents__link toc-highlight">NestedClassesVisibility</a></li><li><a href="#newlineatendoffile" class="table-of-contents__link toc-highlight">NewLineAtEndOfFile</a></li><li><a href="#notabs" class="table-of-contents__link toc-highlight">NoTabs</a></li><li><a href="#nullablebooleancheck" class="table-of-contents__link toc-highlight">NullableBooleanCheck</a></li><li><a href="#objectliteraltolambda" class="table-of-contents__link toc-highlight">ObjectLiteralToLambda</a></li><li><a href="#optionalabstractkeyword" class="table-of-contents__link toc-highlight">OptionalAbstractKeyword</a></li><li><a href="#optionalunit" class="table-of-contents__link toc-highlight">OptionalUnit</a></li><li><a href="#optionalwhenbraces" class="table-of-contents__link toc-highlight"><del>OptionalWhenBraces</del></a></li><li><a href="#prefertooverpairsyntax" class="table-of-contents__link toc-highlight">PreferToOverPairSyntax</a></li><li><a href="#protectedmemberinfinalclass" class="table-of-contents__link toc-highlight">ProtectedMemberInFinalClass</a></li><li><a href="#redundantexplicittype" class="table-of-contents__link toc-highlight">RedundantExplicitType</a></li><li><a href="#redundanthigherordermapusage" class="table-of-contents__link toc-highlight">RedundantHigherOrderMapUsage</a></li><li><a href="#redundantvisibilitymodifierrule" class="table-of-contents__link toc-highlight">RedundantVisibilityModifierRule</a></li><li><a href="#returncount" class="table-of-contents__link toc-highlight">ReturnCount</a></li><li><a href="#safecast" class="table-of-contents__link toc-highlight">SafeCast</a></li><li><a href="#serialversionuidinserializableclass" class="table-of-contents__link toc-highlight">SerialVersionUIDInSerializableClass</a></li><li><a href="#spacingbetweenpackageandimports" class="table-of-contents__link toc-highlight">SpacingBetweenPackageAndImports</a></li><li><a href="#stringshouldberawstring" class="table-of-contents__link toc-highlight">StringShouldBeRawString</a></li><li><a href="#throwscount" class="table-of-contents__link toc-highlight">ThrowsCount</a></li><li><a href="#trailingwhitespace" class="table-of-contents__link toc-highlight">TrailingWhitespace</a></li><li><a href="#trimmultilinerawstring" class="table-of-contents__link toc-highlight">TrimMultilineRawString</a></li><li><a href="#underscoresinnumericliterals" class="table-of-contents__link toc-highlight">UnderscoresInNumericLiterals</a></li><li><a href="#unnecessaryabstractclass" class="table-of-contents__link toc-highlight">UnnecessaryAbstractClass</a></li><li><a href="#unnecessaryannotationusesitetarget" class="table-of-contents__link toc-highlight">UnnecessaryAnnotationUseSiteTarget</a></li><li><a href="#unnecessaryapply" class="table-of-contents__link toc-highlight">UnnecessaryApply</a></li><li><a href="#unnecessarybackticks" class="table-of-contents__link toc-highlight">UnnecessaryBackticks</a></li><li><a href="#unnecessarybracesaroundtrailinglambda" class="table-of-contents__link toc-highlight">UnnecessaryBracesAroundTrailingLambda</a></li><li><a href="#unnecessaryfilter" class="table-of-contents__link toc-highlight">UnnecessaryFilter</a></li><li><a href="#unnecessaryinheritance" class="table-of-contents__link toc-highlight">UnnecessaryInheritance</a></li><li><a href="#unnecessaryinnerclass" class="table-of-contents__link toc-highlight">UnnecessaryInnerClass</a></li><li><a href="#unnecessarylet" class="table-of-contents__link toc-highlight">UnnecessaryLet</a></li><li><a href="#unnecessaryparentheses" class="table-of-contents__link toc-highlight">UnnecessaryParentheses</a></li><li><a href="#untilinsteadofrangeto" class="table-of-contents__link toc-highlight">UntilInsteadOfRangeTo</a></li><li><a href="#unusedimports" class="table-of-contents__link toc-highlight">UnusedImports</a></li><li><a href="#unusedparameter" class="table-of-contents__link toc-highlight">UnusedParameter</a></li><li><a href="#unusedprivateclass" class="table-of-contents__link toc-highlight">UnusedPrivateClass</a></li><li><a href="#unusedprivatemember" class="table-of-contents__link toc-highlight">UnusedPrivateMember</a></li><li><a href="#unusedprivateproperty" class="table-of-contents__link toc-highlight">UnusedPrivateProperty</a></li><li><a href="#useanyornoneinsteadoffind" class="table-of-contents__link toc-highlight">UseAnyOrNoneInsteadOfFind</a></li><li><a href="#usearrayliteralsinannotations" class="table-of-contents__link toc-highlight">UseArrayLiteralsInAnnotations</a></li><li><a href="#usechecknotnull" class="table-of-contents__link toc-highlight">UseCheckNotNull</a></li><li><a href="#usecheckorerror" class="table-of-contents__link toc-highlight">UseCheckOrError</a></li><li><a href="#usedataclass" class="table-of-contents__link toc-highlight">UseDataClass</a></li><li><a href="#useemptycounterpart" class="table-of-contents__link toc-highlight">UseEmptyCounterpart</a></li><li><a href="#useifemptyorifblank" class="table-of-contents__link toc-highlight">UseIfEmptyOrIfBlank</a></li><li><a href="#useifinsteadofwhen" class="table-of-contents__link toc-highlight">UseIfInsteadOfWhen</a></li><li><a href="#useisnullorempty" class="table-of-contents__link toc-highlight">UseIsNullOrEmpty</a></li><li><a href="#uselet" class="table-of-contents__link toc-highlight">UseLet</a></li><li><a href="#useorempty" class="table-of-contents__link toc-highlight">UseOrEmpty</a></li><li><a href="#userequire" class="table-of-contents__link toc-highlight">UseRequire</a></li><li><a href="#userequirenotnull" class="table-of-contents__link toc-highlight">UseRequireNotNull</a></li><li><a href="#usesumofinsteadofflatmapsize" class="table-of-contents__link toc-highlight">UseSumOfInsteadOfFlatMapSize</a></li><li><a href="#uselesscallonnotnull" class="table-of-contents__link toc-highlight">UselessCallOnNotNull</a></li><li><a href="#utilityclasswithpublicconstructor" class="table-of-contents__link toc-highlight">UtilityClassWithPublicConstructor</a></li><li><a href="#varcouldbeval" class="table-of-contents__link toc-highlight">VarCouldBeVal</a></li><li><a href="#wildcardimport" class="table-of-contents__link toc-highlight">WildcardImport</a></li></ul></div></div></div></div></main></div></div></div><footer class="footer footer--dark"><div class="container container-fluid"><div class="row footer__links"><div class="col footer__col"><div class="footer__title">Docs</div><ul class="footer__items clean-list"><li class="footer__item"><a class="footer__link-item" href="/docs/gettingstarted/gradle">Getting Started with Gradle</a></li><li class="footer__item"><a class="footer__link-item" href="/docs/gettingstarted/cli">Getting Started with the CLI</a></li><li class="footer__item"><a class="footer__link-item" href="/docs/rules/comments">Rules Documentation</a></li></ul></div><div class="col footer__col"><div class="footer__title">Community</div><ul class="footer__items clean-list"><li 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