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analytics-action-close="Callout Profile dismissed" analytics-label="Create Collection Callout" class="devsite-page-bookmark-tooltip nocontent" dismiss-button="true" id="devsite-collections-dropdown" dismiss-button-text="Dismiss" close-button-text="Got it"> <devsite-bookmark></devsite-bookmark> <span slot="popout-heading"> Stay organized with collections </span> <span slot="popout-contents"> Save and categorize content based on your preferences. </span> </devsite-feature-tooltip> <devsite-toc class="devsite-nav" depth="2" devsite-toc-embedded > </devsite-toc> <devsite-recommendations-dropdown class="nocontent"></devsite-recommendations-dropdown> <div class="devsite-article-body clearfix devsite-no-page-title"> <h1 id="android_ktx" class="page-title" data-text="Android KTX   Part of Android Jetpack." tabindex="-1">Android KTX   <span class="dac-jetpack"><span>Part of <a href="/jetpack">Android Jetpack</a>.</span></span></h1> <div class="video-wrapper"> <iframe class="devsite-embedded-youtube-video" data-video-id="nKzvYBMdm54" data-autohide="1" data-showinfo="0" frameborder="0" allowfullscreen> </iframe> </div> <p>Android KTX is a set of Kotlin extensions that are included with Android <a href="/jetpack">Jetpack</a> and other Android libraries. KTX extensions provide concise, idiomatic Kotlin to Jetpack, Android platform, and other APIs. To do so, these extensions leverage several Kotlin language features, including the following:</p> <ul> <li>Extension functions</li> <li>Extension properties</li> <li>Lambdas</li> <li>Named parameters</li> <li>Parameter default values</li> <li>Coroutines</li> </ul> <p>As an example, when working with <a href="/reference/android/content/SharedPreferences"><code translate="no" dir="ltr">SharedPreferences</code></a>, you must <a href="/reference/android/content/SharedPreferences#edit()">create an editor</a> before you can make modifications to the preferences data. You must also apply or commit those changes when you are finished editing, as shown in the following example:</p> <div></div><devsite-code><pre class="devsite-click-to-copy" translate="no" dir="ltr" is-upgraded syntax="Kotlin"><code translate="no" dir="ltr"><span class="devsite-syntax-n">sharedPreferences</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">.</span><span class="devsite-syntax-na">edit</span><span class="devsite-syntax-p">()</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-c1">// create an Editor</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">.</span><span class="devsite-syntax-na">putBoolean</span><span class="devsite-syntax-p">(</span><span class="devsite-syntax-s">"key"</span><span class="devsite-syntax-p">,</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">value</span><span class="devsite-syntax-p">)</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">.</span><span class="devsite-syntax-na">apply</span><span class="devsite-syntax-p">()</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-c1">// write to disk asynchronously</span> </code></pre></devsite-code> <p>Kotlin lambdas are a perfect fit for this use case. They allow you to take a more concise approach by passing a block of code to execute after the editor is created, letting the code execute, and then letting the <code translate="no" dir="ltr">SharedPreferences</code> API apply the changes atomically.</p> <p>Here&#39;s an example of one of the Android KTX Core functions, <a href="/reference/kotlin/androidx/core/content/package-summary#edit"><code translate="no" dir="ltr">SharedPreferences.edit</code></a>, which adds an edit function to <code translate="no" dir="ltr">SharedPreferences</code>. This function takes an optional <code translate="no" dir="ltr">boolean</code> flag as its first argument that indicates whether to commit or apply the changes. It also receives an action to perform on the <code translate="no" dir="ltr">SharedPreferences</code> editor in the form of a lambda.</p> <div></div><devsite-code><pre class="devsite-click-to-copy" translate="no" dir="ltr" is-upgraded syntax="Kotlin"><code translate="no" dir="ltr"><span class="devsite-syntax-c1">// SharedPreferences.edit extension function signature from Android KTX - Core</span> <span class="devsite-syntax-c1">// inline fun SharedPreferences.edit(</span> <span class="devsite-syntax-c1">// commit: Boolean = false,</span> <span class="devsite-syntax-c1">// action: SharedPreferences.Editor.() -&gt; Unit)</span> <span class="devsite-syntax-c1">// Commit a new value asynchronously</span> <span class="devsite-syntax-n">sharedPreferences</span><span class="devsite-syntax-p">.</span><span class="devsite-syntax-na">edit</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">{</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">putBoolean</span><span class="devsite-syntax-p">(</span><span class="devsite-syntax-s">"key"</span><span class="devsite-syntax-p">,</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">value</span><span class="devsite-syntax-p">)</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">}</span> <span class="devsite-syntax-c1">// Commit a new value synchronously</span> <span class="devsite-syntax-n">sharedPreferences</span><span class="devsite-syntax-p">.</span><span class="devsite-syntax-na">edit</span><span class="devsite-syntax-p">(</span><span class="devsite-syntax-n">commit</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-o">=</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-kc">true</span><span class="devsite-syntax-p">)</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">{</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">putBoolean</span><span class="devsite-syntax-p">(</span><span class="devsite-syntax-s">"key"</span><span class="devsite-syntax-p">,</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">value</span><span class="devsite-syntax-p">)</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">}</span> </code></pre></devsite-code> <p>The caller can choose whether to commit or apply the changes. The <code translate="no" dir="ltr">action</code> lambda is itself an anonymous extension function on <code translate="no" dir="ltr">SharedPreferences.Editor</code> which returns <code translate="no" dir="ltr">Unit</code>, as indicated by its signature. This is why inside the block, you are able to perform the work directly on the <code translate="no" dir="ltr">SharedPreferences.Editor</code>.</p> <p>Finally, the <code translate="no" dir="ltr">SharedPreferences.edit()</code> signature contains the <code translate="no" dir="ltr">inline</code> keyword. This keyword tells the Kotlin compiler that it should copy and paste (or <em>inline</em>) the compiled bytecode for the function each time the function is used. This avoids the overhead of instantiating a new class for every <code translate="no" dir="ltr">action</code> each time this function is called.</p> <p>This pattern of passing code using lambdas, applying sensible defaults that can be overridden, and adding these behaviors to existing APIs using <code translate="no" dir="ltr">inline</code> extension functions is typical of the enhancements provided by the Android KTX library.</p> <h2 id="use-ktx" data-text="Use Android KTX in your project" tabindex="-1">Use Android KTX in your project</h2> <p>To start using Android KTX, add the following dependency to your project&#39;s <code translate="no" dir="ltr">build.gradle</code> file:</p> <div> <div class="ds-selector-tabs"><section><h3 id="groovy" data-text="Groovy" tabindex="-1">Groovy</h3> <div></div><devsite-code><pre class="devsite-click-to-copy" translate="no" dir="ltr" is-upgraded syntax="Groovy"><span class="devsite-syntax-n">repositories</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-o">{</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">google</span><span class="devsite-syntax-o">()</span> <span class="devsite-syntax-o">}</span></pre></devsite-code> </section><section><h3 id="kts" data-text="Kotlin" tabindex="-1">Kotlin</h3> <div></div><devsite-code><pre class="devsite-click-to-copy" translate="no" dir="ltr" is-upgraded syntax="Kotlin"><span class="devsite-syntax-n">repositories</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">{</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">google</span><span class="devsite-syntax-p">()</span> <span class="devsite-syntax-p">}</span></pre></devsite-code> </section></div> </div> <h2 id="modules" data-text="AndroidX Modules" tabindex="-1">AndroidX Modules</h2> <p>Android KTX is organized into modules, where each module contains one or more packages.</p> <p>You must include a dependency for each module artifact in your app&#39;s <code translate="no" dir="ltr">build.gradle</code> file. Remember to append the version number to the artifact. You can find the latest version numbers in each artifact&#39;s corresponding section in this topic.</p> <p>Android KTX contains a <a href="#core">single core module</a> that provides Kotlin extensions for common framework APIs and several domain-specific extensions.</p> <p>With the exception of the core module, all KTX module artifacts replace the underlying Java dependency in your <code translate="no" dir="ltr">build.gradle</code> file. For example, you can replace a <code translate="no" dir="ltr">androidx.fragment:fragment</code> dependency with <code translate="no" dir="ltr">androidx.fragment:fragment-ktx</code>. This syntax helps to better manage versioning and does not add additional dependency declaration requirements.</p> <h3 id="core" data-text="Core KTX" tabindex="-1">Core KTX</h3> <p>The Core KTX module provides extensions for common libraries that are part of the Android framework. These libraries do not have Java-based dependencies that you need to add to <code translate="no" dir="ltr">build.gradle</code>.</p> <p>To include this module, add the following to your app&#39;s <code translate="no" dir="ltr">build.gradle</code> file:</p> <div> <div class="ds-selector-tabs"><section><h3 id="groovy" data-text="Groovy" tabindex="-1">Groovy</h3> <div></div><devsite-code><pre class="devsite-click-to-copy" translate="no" dir="ltr" is-upgraded syntax="Groovy"><span class="devsite-syntax-n">dependencies</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-o">{</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">implementation</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-s2">"androidx.core:core-ktx:1.15.0"</span> <span class="devsite-syntax-o">}</span></pre></devsite-code> </section><section><h3 id="kts" data-text="Kotlin" tabindex="-1">Kotlin</h3> <div></div><devsite-code><pre class="devsite-click-to-copy" translate="no" dir="ltr" is-upgraded syntax="Kotlin"><span class="devsite-syntax-n">dependencies</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">{</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">implementation</span><span class="devsite-syntax-p">(</span><span class="devsite-syntax-s">"androidx.core:core-ktx:1.15.0"</span><span class="devsite-syntax-p">)</span> <span class="devsite-syntax-p">}</span></pre></devsite-code> </section></div> </div> <p>Here&#39;s a list of the packages that are contained in the Core KTX module:</p> <ul> <li><a href="/reference/kotlin/androidx/core/animation/package-summary">androidx.core.animation</a></li> <li><a href="/reference/kotlin/androidx/core/content/package-summary">androidx.core.content</a></li> <li><a href="/reference/kotlin/androidx/core/content/res/package-summary">androidx.core.content.res</a></li> <li><a href="/reference/kotlin/androidx/core/database/package-summary">androidx.core.database</a></li> <li><a href="/reference/kotlin/androidx/core/database/sqlite/package-summary">androidx.core.database.sqlite</a></li> <li><a href="/reference/kotlin/androidx/core/graphics/package-summary">androidx.core.graphics</a></li> <li><a href="/reference/kotlin/androidx/core/graphics/drawable/package-summary">androidx.core.graphics.drawable</a></li> <li><a href="/reference/kotlin/androidx/core/location/package-summary">androidx.core.location</a></li> <li><a href="/reference/kotlin/androidx/core/net/package-summary">androidx.core.net</a></li> <li><a href="/reference/kotlin/androidx/core/os/package-summary">androidx.core.os</a></li> <li><a href="/reference/kotlin/androidx/core/text/package-summary">androidx.core.text</a></li> <li><a href="/reference/kotlin/androidx/core/transition/package-summary">androidx.core.transition</a></li> <li><a href="/reference/kotlin/androidx/core/util/package-summary">androidx.core.util</a></li> <li><a href="/reference/kotlin/androidx/core/view/package-summary">androidx.core.view</a></li> <li><a href="/reference/kotlin/androidx/core/widget/package-summary">androidx.core.widget</a></li> </ul> <h3 id="collection" data-text="Collection KTX" tabindex="-1">Collection KTX</h3> <p>The Collection extensions contain utility functions for working with Android&#39;s memory-efficient collection libraries, including <code translate="no" dir="ltr">ArrayMap</code>, <code translate="no" dir="ltr">LongSparseArray</code>, <code translate="no" dir="ltr">LruCache</code>, and others.</p> <p>To use this module, add the following to your app&#39;s <code translate="no" dir="ltr">build.gradle</code> file:</p> <div> <div class="ds-selector-tabs"><section><h3 id="groovy" data-text="Groovy" tabindex="-1">Groovy</h3> <div></div><devsite-code><pre class="devsite-click-to-copy" translate="no" dir="ltr" is-upgraded syntax="Groovy"><span class="devsite-syntax-n">dependencies</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-o">{</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">implementation</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-s2">"androidx.collection:collection-ktx:1.4.5"</span> <span class="devsite-syntax-o">}</span></pre></devsite-code> </section><section><h3 id="kts" data-text="Kotlin" tabindex="-1">Kotlin</h3> <div></div><devsite-code><pre class="devsite-click-to-copy" translate="no" dir="ltr" is-upgraded syntax="Kotlin"><span class="devsite-syntax-n">dependencies</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">{</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">implementation</span><span class="devsite-syntax-p">(</span><span class="devsite-syntax-s">"androidx.collection:collection-ktx:1.4.5"</span><span class="devsite-syntax-p">)</span> <span class="devsite-syntax-p">}</span></pre></devsite-code> </section></div> </div> <p>Collection extensions take advantage of Kotlin’s operator overloading to simplify things like collection concatenation, as shown in the following example:</p> <div></div><devsite-code><pre class="devsite-click-to-copy" translate="no" dir="ltr" is-upgraded syntax="Kotlin"><code translate="no" dir="ltr"><span class="devsite-syntax-c1">// Combine 2 ArraySets into 1.</span> <span class="devsite-syntax-kd">val</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-nv">combinedArraySet</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-o">=</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">arraySetOf</span><span class="devsite-syntax-p">(</span><span class="devsite-syntax-m">1</span><span class="devsite-syntax-p">,</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-m">2</span><span class="devsite-syntax-p">,</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-m">3</span><span class="devsite-syntax-p">)</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-o">+</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">arraySetOf</span><span class="devsite-syntax-p">(</span><span class="devsite-syntax-m">4</span><span class="devsite-syntax-p">,</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-m">5</span><span class="devsite-syntax-p">,</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-m">6</span><span class="devsite-syntax-p">)</span> <span class="devsite-syntax-c1">// Combine with numbers to create a new sets.</span> <span class="devsite-syntax-kd">val</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-nv">newArraySet</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-o">=</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">combinedArraySet</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-o">+</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-m">7</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-o">+</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-m">8</span> </code></pre></devsite-code> <h3 id="fragment" data-text="Fragment KTX" tabindex="-1">Fragment KTX</h3> <p>The <a href="/reference/kotlin/androidx/fragment/app/package-summary#extension-functions-summary">Fragment KTX module</a> provides a number of extensions to simplify the fragment API.</p> <p>To include this module, add the following to your app&#39;s <code translate="no" dir="ltr">build.gradle</code> file:</p> <div> <div class="ds-selector-tabs"><section><h3 id="groovy" data-text="Groovy" tabindex="-1">Groovy</h3> <div></div><devsite-code><pre class="devsite-click-to-copy" translate="no" dir="ltr" is-upgraded syntax="Groovy"><span class="devsite-syntax-n">dependencies</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-o">{</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">implementation</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-s2">"androidx.fragment:fragment-ktx:1.8.5"</span> <span class="devsite-syntax-o">}</span></pre></devsite-code> </section><section><h3 id="kts" data-text="Kotlin" tabindex="-1">Kotlin</h3> <div></div><devsite-code><pre class="devsite-click-to-copy" translate="no" dir="ltr" is-upgraded syntax="Kotlin"><span class="devsite-syntax-n">dependencies</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">{</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">implementation</span><span class="devsite-syntax-p">(</span><span class="devsite-syntax-s">"androidx.fragment:fragment-ktx:1.8.5"</span><span class="devsite-syntax-p">)</span> <span class="devsite-syntax-p">}</span></pre></devsite-code> </section></div> </div> <p>With the Fragment KTX module, you can simplify fragment transactions with lambdas, for example:</p> <div></div><devsite-code><pre class="devsite-click-to-copy" translate="no" dir="ltr" is-upgraded syntax="Kotlin"><code translate="no" dir="ltr"><span class="devsite-syntax-n">fragmentManager</span><span class="devsite-syntax-p">().</span><span class="devsite-syntax-na">commit</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">{</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">addToBackStack</span><span class="devsite-syntax-p">(</span><span class="devsite-syntax-s">"..."</span><span class="devsite-syntax-p">)</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">setCustomAnimations</span><span class="devsite-syntax-p">(</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">R</span><span class="devsite-syntax-p">.</span><span class="devsite-syntax-na">anim</span><span class="devsite-syntax-p">.</span><span class="devsite-syntax-na">enter_anim</span><span class="devsite-syntax-p">,</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">R</span><span class="devsite-syntax-p">.</span><span class="devsite-syntax-na">anim</span><span class="devsite-syntax-p">.</span><span class="devsite-syntax-na">exit_anim</span><span class="devsite-syntax-p">)</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">add</span><span class="devsite-syntax-p">(</span><span class="devsite-syntax-n">fragment</span><span class="devsite-syntax-p">,</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-s">"..."</span><span class="devsite-syntax-p">)</span> <span class="devsite-syntax-p">}</span> </code></pre></devsite-code> <p>You can also bind to a <code translate="no" dir="ltr">ViewModel</code> in one line by using the <code translate="no" dir="ltr">viewModels</code> and <code translate="no" dir="ltr">activityViewModels</code> property delegates:</p> <div></div><devsite-code><pre class="devsite-click-to-copy" translate="no" dir="ltr" is-upgraded syntax="Kotlin"><code translate="no" dir="ltr"><span class="devsite-syntax-c1">// Get a reference to the ViewModel scoped to this Fragment</span> <span class="devsite-syntax-kd">val</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-nv">viewModel</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-k">by</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">viewModels&lt;MyViewModel&gt;</span><span class="devsite-syntax-p">()</span> <span class="devsite-syntax-c1">// Get a reference to the ViewModel scoped to its Activity</span> <span class="devsite-syntax-kd">val</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-nv">viewModel</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-k">by</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">activityViewModels&lt;MyViewModel&gt;</span><span class="devsite-syntax-p">()</span> </code></pre></devsite-code> <h3 id="lifecycle" data-text="Lifecycle KTX" tabindex="-1">Lifecycle KTX</h3> <p>Lifecycle KTX defines a <code translate="no" dir="ltr">LifecycleScope</code> for each <a href="/topic/libraries/architecture/lifecycle"><code translate="no" dir="ltr">Lifecycle</code></a> object. Any coroutine launched in this scope is canceled when the <code translate="no" dir="ltr">Lifecycle</code> is destroyed. You can access the <code translate="no" dir="ltr">CoroutineScope</code> of the <code translate="no" dir="ltr">Lifecycle</code> by using the <code translate="no" dir="ltr">lifecycle.coroutineScope</code> or <code translate="no" dir="ltr">lifecycleOwner.lifecycleScope</code> properties.</p> <p>To include this module, add the following to your app&#39;s <code translate="no" dir="ltr">build.gradle</code> file:</p> <div> <div class="ds-selector-tabs"><section><h3 id="groovy" data-text="Groovy" tabindex="-1">Groovy</h3> <div></div><devsite-code><pre class="devsite-click-to-copy" translate="no" dir="ltr" is-upgraded syntax="Groovy"><span class="devsite-syntax-n">dependencies</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-o">{</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">implementation</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-s2">"androidx.lifecycle:lifecycle-runtime-ktx:2.8.7"</span> <span class="devsite-syntax-o">}</span></pre></devsite-code> </section><section><h3 id="kts" data-text="Kotlin" tabindex="-1">Kotlin</h3> <div></div><devsite-code><pre class="devsite-click-to-copy" translate="no" dir="ltr" is-upgraded syntax="Kotlin"><span class="devsite-syntax-n">dependencies</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">{</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">implementation</span><span class="devsite-syntax-p">(</span><span class="devsite-syntax-s">"androidx.lifecycle:lifecycle-runtime-ktx:2.8.7"</span><span class="devsite-syntax-p">)</span> <span class="devsite-syntax-p">}</span></pre></devsite-code> </section></div> </div> <p>The following example demonstrates how to use <code translate="no" dir="ltr">lifecycleOwner.lifecycleScope</code> to create precomputed text asynchronously:</p> <div></div><devsite-code><pre class="devsite-click-to-copy" translate="no" dir="ltr" is-upgraded syntax="Kotlin"><code translate="no" dir="ltr"><span class="devsite-syntax-kd">class</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-nc">MyFragment</span><span class="devsite-syntax-p">:</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">Fragment</span><span class="devsite-syntax-p">()</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">{</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-kd">override</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-kd">fun</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-nf">onViewCreated</span><span class="devsite-syntax-p">(</span><span class="devsite-syntax-n">view</span><span class="devsite-syntax-p">:</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">View</span><span class="devsite-syntax-p">,</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">savedInstanceState</span><span class="devsite-syntax-p">:</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">Bundle?)</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">{</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-k">super</span><span class="devsite-syntax-p">.</span><span class="devsite-syntax-na">onViewCreated</span><span class="devsite-syntax-p">(</span><span class="devsite-syntax-n">view</span><span class="devsite-syntax-p">,</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">savedInstanceState</span><span class="devsite-syntax-p">)</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">viewLifecycleOwner</span><span class="devsite-syntax-p">.</span><span class="devsite-syntax-na">lifecycleScope</span><span class="devsite-syntax-p">.</span><span class="devsite-syntax-na">launch</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">{</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-kd">val</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-nv">params</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-o">=</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">TextViewCompat</span><span class="devsite-syntax-p">.</span><span class="devsite-syntax-na">getTextMetricsParams</span><span class="devsite-syntax-p">(</span><span class="devsite-syntax-n">textView</span><span class="devsite-syntax-p">)</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-kd">val</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-nv">precomputedText</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-o">=</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">withContext</span><span class="devsite-syntax-p">(</span><span class="devsite-syntax-n">Dispatchers</span><span class="devsite-syntax-p">.</span><span class="devsite-syntax-na">Default</span><span class="devsite-syntax-p">)</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">{</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">PrecomputedTextCompat</span><span class="devsite-syntax-p">.</span><span class="devsite-syntax-na">create</span><span class="devsite-syntax-p">(</span><span class="devsite-syntax-n">longTextContent</span><span class="devsite-syntax-p">,</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">params</span><span class="devsite-syntax-p">)</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">}</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">TextViewCompat</span><span class="devsite-syntax-p">.</span><span class="devsite-syntax-na">setPrecomputedText</span><span class="devsite-syntax-p">(</span><span class="devsite-syntax-n">textView</span><span class="devsite-syntax-p">,</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">precomputedText</span><span class="devsite-syntax-p">)</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">}</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">}</span> <span class="devsite-syntax-p">}</span> </code></pre></devsite-code> <h3 id="livedata" data-text="LiveData KTX" tabindex="-1">LiveData KTX</h3> <p>When using LiveData, you might need to calculate values asynchronously. For example, you might want to retrieve a user&#39;s preferences and serve them to your UI. For these cases, LiveData KTX provides a <code translate="no" dir="ltr">liveData</code> builder function that calls a <code translate="no" dir="ltr">suspend</code> function and serves the result as a <code translate="no" dir="ltr">LiveData</code> object.</p> <p>To include this module, add the following to your app&#39;s <code translate="no" dir="ltr">build.gradle</code> file:</p> <div> <div class="ds-selector-tabs"><section><h3 id="groovy" data-text="Groovy" tabindex="-1">Groovy</h3> <div></div><devsite-code><pre class="devsite-click-to-copy" translate="no" dir="ltr" is-upgraded syntax="Groovy"><span class="devsite-syntax-n">dependencies</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-o">{</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">implementation</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-s2">"androidx.lifecycle:lifecycle-livedata-ktx:2.8.7"</span> <span class="devsite-syntax-o">}</span></pre></devsite-code> </section><section><h3 id="kts" data-text="Kotlin" tabindex="-1">Kotlin</h3> <div></div><devsite-code><pre class="devsite-click-to-copy" translate="no" dir="ltr" is-upgraded syntax="Kotlin"><span class="devsite-syntax-n">dependencies</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">{</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">implementation</span><span class="devsite-syntax-p">(</span><span class="devsite-syntax-s">"androidx.lifecycle:lifecycle-livedata-ktx:2.8.7"</span><span class="devsite-syntax-p">)</span> <span class="devsite-syntax-p">}</span></pre></devsite-code> </section></div> </div> <p>In the following example, <code translate="no" dir="ltr">loadUser()</code> is a suspend function declared elsewhere. You can use the <code translate="no" dir="ltr">liveData</code> builder function to call <code translate="no" dir="ltr">loadUser()</code> asynchronously, and then use <code translate="no" dir="ltr">emit()</code> to emit the result:</p> <div></div><devsite-code><pre class="devsite-click-to-copy" translate="no" dir="ltr" is-upgraded syntax="Kotlin"><code translate="no" dir="ltr"><span class="devsite-syntax-kd">val</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-nv">user</span><span class="devsite-syntax-p">:</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">LiveData&lt;User&gt;</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-o">=</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">liveData</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">{</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-kd">val</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-nv">data</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-o">=</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">database</span><span class="devsite-syntax-p">.</span><span class="devsite-syntax-na">loadUser</span><span class="devsite-syntax-p">()</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-c1">// loadUser is a suspend function.</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">emit</span><span class="devsite-syntax-p">(</span><span class="devsite-syntax-n">data</span><span class="devsite-syntax-p">)</span> <span class="devsite-syntax-p">}</span> </code></pre></devsite-code> <p>For more information on using coroutines with <code translate="no" dir="ltr">LiveData</code>, see <a href="/topic/libraries/architecture/coroutines#livedata">Use Kotlin coroutines with Architecture components</a>.</p> <h3 id="navigation" data-text="Navigation KTX" tabindex="-1">Navigation KTX</h3> <p>Each component of the Navigation library has its own KTX version that adapts the API to be more succinct and Kotlin-idiomatic.</p> <p>To include these modules, add the following to your app&#39;s <code translate="no" dir="ltr">build.gradle</code> file:</p> <div> <div class="ds-selector-tabs"><section><h3 id="groovy" data-text="Groovy" tabindex="-1">Groovy</h3> <pre class="prettyprint lang-groovy" translate="no" dir="ltr"> dependencies { implementation "androidx.navigation:navigation-runtime-ktx:2.8.4" implementation "androidx.navigation:navigation-fragment-ktx:2.8.4" implementation "androidx.navigation:navigation-ui-ktx:2.8.4" } </pre> </section><section><h3 id="kts" data-text="Kotlin" tabindex="-1">Kotlin</h3> <pre class="prettyprint lang-kotlin" translate="no" dir="ltr"> dependencies { implementation("androidx.navigation:navigation-runtime-ktx:2.8.4") implementation("androidx.navigation:navigation-fragment-ktx:2.8.4") implementation("androidx.navigation:navigation-ui-ktx:2.8.4") } </pre> </section></div> </div> <p>Use the extension functions and property delegation to access destination arguments and navigate to destinations, as shown in the following example:</p> <div></div><devsite-code><pre class="devsite-click-to-copy" translate="no" dir="ltr" is-upgraded syntax="Kotlin"><code translate="no" dir="ltr"><span class="devsite-syntax-kd">class</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-nc">MyDestination</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">:</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">Fragment</span><span class="devsite-syntax-p">()</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">{</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-c1">// Type-safe arguments are accessed from the bundle.</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-kd">val</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-nv">args</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-k">by</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">navArgs&lt;MyDestinationArgs&gt;</span><span class="devsite-syntax-p">()</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">...</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-kd">override</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-kd">fun</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-nf">onViewCreated</span><span class="devsite-syntax-p">(</span><span class="devsite-syntax-n">view</span><span class="devsite-syntax-p">:</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">View</span><span class="devsite-syntax-p">,</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">savedInstanceState</span><span class="devsite-syntax-p">:</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">Bundle?)</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">{</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">view</span><span class="devsite-syntax-p">.</span><span class="devsite-syntax-na">findViewById&lt;Button&gt;</span><span class="devsite-syntax-p">(</span><span class="devsite-syntax-n">R</span><span class="devsite-syntax-p">.</span><span class="devsite-syntax-na">id</span><span class="devsite-syntax-p">.</span><span class="devsite-syntax-na">next</span><span class="devsite-syntax-p">)</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">.</span><span class="devsite-syntax-na">setOnClickListener</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">{</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-c1">// Fragment extension added to retrieve a NavController from</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-c1">// any destination.</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">findNavController</span><span class="devsite-syntax-p">().</span><span class="devsite-syntax-na">navigate</span><span class="devsite-syntax-p">(</span><span class="devsite-syntax-n">R</span><span class="devsite-syntax-p">.</span><span class="devsite-syntax-na">id</span><span class="devsite-syntax-p">.</span><span class="devsite-syntax-na">action_to_next_destination</span><span class="devsite-syntax-p">)</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">}</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">}</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">...</span> <span class="devsite-syntax-p">}</span> </code></pre></devsite-code> <h3 id="palette" data-text="Palette KTX" tabindex="-1">Palette KTX</h3> <p>The <a href="/reference/kotlin/androidx/palette/graphics/package-summary#extension-functions-summary">Palette KTX module</a> offers idiomatic Kotlin support for working with color palettes.</p> <p>To use this module, add the following to your app&#39;s <code translate="no" dir="ltr">build.gradle</code> file:</p> <div> <div class="ds-selector-tabs"><section><h3 id="groovy" data-text="Groovy" tabindex="-1">Groovy</h3> <div></div><devsite-code><pre class="devsite-click-to-copy" translate="no" dir="ltr" is-upgraded syntax="Groovy"><span class="devsite-syntax-n">dependencies</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-o">{</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">implementation</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-s2">"androidx.palette:palette-ktx:1.0.0"</span> <span class="devsite-syntax-o">}</span></pre></devsite-code> </section><section><h3 id="kts" data-text="Kotlin" tabindex="-1">Kotlin</h3> <div></div><devsite-code><pre class="devsite-click-to-copy" translate="no" dir="ltr" is-upgraded syntax="Kotlin"><span class="devsite-syntax-n">dependencies</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">{</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">implementation</span><span class="devsite-syntax-p">(</span><span class="devsite-syntax-s">"androidx.palette:palette-ktx:1.0.0"</span><span class="devsite-syntax-p">)</span> <span class="devsite-syntax-p">}</span></pre></devsite-code> </section></div> </div> <p>As an example, when working with a <code translate="no" dir="ltr">Palette</code> instance, you can retrieve the <code translate="no" dir="ltr">selected</code> swatch for a given <code translate="no" dir="ltr">target</code> by using the get operator (<code translate="no" dir="ltr">[ ]</code>):</p> <div></div><devsite-code><pre class="devsite-click-to-copy" translate="no" dir="ltr" is-upgraded syntax="Kotlin"><code translate="no" dir="ltr"><span class="devsite-syntax-kd">val</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-nv">palette</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-o">=</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">Palette</span><span class="devsite-syntax-p">.</span><span class="devsite-syntax-na">from</span><span class="devsite-syntax-p">(</span><span class="devsite-syntax-n">bitmap</span><span class="devsite-syntax-p">).</span><span class="devsite-syntax-na">generate</span><span class="devsite-syntax-p">()</span> <span class="devsite-syntax-kd">val</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-nv">swatch</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-o">=</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">palette</span><span class="devsite-syntax-o">[</span><span class="devsite-syntax-n">target</span><span class="devsite-syntax-o">]</span> </code></pre></devsite-code> <h3 id="reactive" data-text="Reactive Streams KTX" tabindex="-1">Reactive Streams KTX</h3> <p>Reactive Streams KTX module lets you create an observable <code translate="no" dir="ltr">LiveData</code> stream from a <code translate="no" dir="ltr">ReactiveStreams</code> publisher.</p> <p>To include this module, add the following to your app&#39;s <code translate="no" dir="ltr">build.gradle</code> file:</p> <div> <div class="ds-selector-tabs"><section><h3 id="groovy" data-text="Groovy" tabindex="-1">Groovy</h3> <div></div><devsite-code><pre class="devsite-click-to-copy" translate="no" dir="ltr" is-upgraded syntax="Groovy"><span class="devsite-syntax-n">dependencies</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-o">{</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">implementation</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-s2">"androidx.lifecycle:lifecycle-reactivestreams-ktx:2.8.7"</span> <span class="devsite-syntax-o">}</span></pre></devsite-code> </section><section><h3 id="kts" data-text="Kotlin" tabindex="-1">Kotlin</h3> <div></div><devsite-code><pre class="devsite-click-to-copy" translate="no" dir="ltr" is-upgraded syntax="Kotlin"><span class="devsite-syntax-n">dependencies</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">{</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">implementation</span><span class="devsite-syntax-p">(</span><span class="devsite-syntax-s">"androidx.lifecycle:lifecycle-reactivestreams-ktx:2.8.7"</span><span class="devsite-syntax-p">)</span> <span class="devsite-syntax-p">}</span></pre></devsite-code> </section></div> </div> <p>As an example, assume a database with a small list of users. In your app, you load the database into memory and then display user data in your UI. To achieve this, you might use <a href="https://github.com/ReactiveX/RxJava" class="external">RxJava</a>. The <a href="/topic/libraries/architecture/room"><code translate="no" dir="ltr">Room</code></a> Jetpack component can retrieve the user list as a <code translate="no" dir="ltr">Flowable</code>. In this scenario, you must also manage the Rx publisher subscription across the life of your fragment or activity.</p> <p>With <code translate="no" dir="ltr">LiveDataReactiveStreams</code>, however, you can benefit from RxJava and its rich set of operators and work-scheduling capabilities while also working with the simplicity of <code translate="no" dir="ltr">LiveData</code>, as shown in the following example:</p> <div></div><devsite-code><pre class="devsite-click-to-copy" translate="no" dir="ltr" is-upgraded syntax="Kotlin"><code translate="no" dir="ltr"><span class="devsite-syntax-kd">val</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-nv">fun</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">getUsersLiveData</span><span class="devsite-syntax-p">()</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">:</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">LiveData&lt;List&lt;User&gt;</span>&gt;<span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">{</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-kd">val</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-nv">users</span><span class="devsite-syntax-p">:</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">Flowable&lt;List&lt;User&gt;</span>&gt;<span class="devsite-syntax-w"> </span><span class="devsite-syntax-o">=</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">dao</span><span class="devsite-syntax-p">.</span><span class="devsite-syntax-na">findUsers</span><span class="devsite-syntax-p">()</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-k">return</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">LiveDataReactiveStreams</span><span class="devsite-syntax-p">.</span><span class="devsite-syntax-na">fromPublisher</span><span class="devsite-syntax-p">(</span><span class="devsite-syntax-n">users</span><span class="devsite-syntax-p">)</span> <span class="devsite-syntax-p">}</span> </code></pre></devsite-code> <h3 id="room" data-text="Room KTX" tabindex="-1">Room KTX</h3> <p>Room extensions add coroutines support for database transactions.</p> <p>To use this module, add the following to your app&#39;s <code translate="no" dir="ltr">build.gradle</code> file:</p> <div> <div class="ds-selector-tabs"><section><h3 id="groovy" data-text="Groovy" tabindex="-1">Groovy</h3> <div></div><devsite-code><pre class="devsite-click-to-copy" translate="no" dir="ltr" is-upgraded syntax="Groovy"><span class="devsite-syntax-n">dependencies</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-o">{</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">implementation</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-s2">"androidx.room:room-ktx:2.6.1"</span> <span class="devsite-syntax-o">}</span></pre></devsite-code> </section><section><h3 id="kts" data-text="Kotlin" tabindex="-1">Kotlin</h3> <div></div><devsite-code><pre class="devsite-click-to-copy" translate="no" dir="ltr" is-upgraded syntax="Kotlin"><span class="devsite-syntax-n">dependencies</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">{</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">implementation</span><span class="devsite-syntax-p">(</span><span class="devsite-syntax-s">"androidx.room:room-ktx:2.6.1"</span><span class="devsite-syntax-p">)</span> <span class="devsite-syntax-p">}</span></pre></devsite-code> </section></div> </div> <p>Here are a couple of examples where Room now uses coroutines. The first example uses a <code translate="no" dir="ltr">suspend</code> function to return a list of <code translate="no" dir="ltr">User</code> objects, while the second utilizes Kotlin&#39;s <a href="https://kotlinlang.org/docs/reference/coroutines/flow.html"><code translate="no" dir="ltr">Flow</code></a> to asynchronously return the <code translate="no" dir="ltr">User</code> list. Note that when using <code translate="no" dir="ltr">Flow</code>, you&#39;re also notified of any changes in the tables you&#39;re querying.</p> <div></div><devsite-code><pre class="devsite-click-to-copy" translate="no" dir="ltr" is-upgraded syntax="Kotlin"><code translate="no" dir="ltr"><span class="devsite-syntax-nd">@Query</span><span class="devsite-syntax-p">(</span><span class="devsite-syntax-s">"SELECT * FROM Users"</span><span class="devsite-syntax-p">)</span> <span class="devsite-syntax-kd">suspend</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-kd">fun</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-nf">getUsers</span><span class="devsite-syntax-p">():</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">List&lt;User&gt;</span> <span class="devsite-syntax-nd">@Query</span><span class="devsite-syntax-p">(</span><span class="devsite-syntax-s">"SELECT * FROM Users"</span><span class="devsite-syntax-p">)</span> <span class="devsite-syntax-kd">fun</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-nf">getUsers</span><span class="devsite-syntax-p">():</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">Flow&lt;List&lt;User&gt;</span>&gt; </code></pre></devsite-code> <h3 id="sqlite" data-text="SQLite KTX" tabindex="-1">SQLite KTX</h3> <p>SQLite extensions wrap SQL-related code in transactions, eliminating a lot of boilerplate code.</p> <p>To use this module, add the following to your app&#39;s <code translate="no" dir="ltr">build.gradle</code> file:</p> <div> <div class="ds-selector-tabs"><section><h3 id="groovy" data-text="Groovy" tabindex="-1">Groovy</h3> <div></div><devsite-code><pre class="devsite-click-to-copy" translate="no" dir="ltr" is-upgraded syntax="Groovy"><span class="devsite-syntax-n">dependencies</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-o">{</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">implementation</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-s2">"androidx.sqlite:sqlite-ktx:2.4.0"</span> <span class="devsite-syntax-o">}</span></pre></devsite-code> </section><section><h3 id="kts" data-text="Kotlin" tabindex="-1">Kotlin</h3> <div></div><devsite-code><pre class="devsite-click-to-copy" translate="no" dir="ltr" is-upgraded syntax="Kotlin"><span class="devsite-syntax-n">dependencies</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">{</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">implementation</span><span class="devsite-syntax-p">(</span><span class="devsite-syntax-s">"androidx.sqlite:sqlite-ktx:2.4.0"</span><span class="devsite-syntax-p">)</span> <span class="devsite-syntax-p">}</span></pre></devsite-code> </section></div> </div> <p>Here&#39;s an example of using the <code translate="no" dir="ltr">transaction</code> extension to perform a database transaction:</p> <div></div><devsite-code><pre class="devsite-click-to-copy" translate="no" dir="ltr" is-upgraded syntax="Kotlin"><code translate="no" dir="ltr"><span class="devsite-syntax-n">db</span><span class="devsite-syntax-p">.</span><span class="devsite-syntax-na">transaction</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">{</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-c1">// insert data</span> <span class="devsite-syntax-p">}</span> </code></pre></devsite-code> <h3 id="viewmodel" data-text="ViewModel KTX" tabindex="-1">ViewModel KTX</h3> <p>The ViewModel KTX library provides a <code translate="no" dir="ltr">viewModelScope()</code> function that makes it easier to launch <a href="/kotlin/coroutines">coroutines</a> from your <code translate="no" dir="ltr">ViewModel</code>. The <a href="https://kotlin.github.io/kotlinx.coroutines/kotlinx-coroutines-core/kotlinx.coroutines/-coroutine-scope/" class="external"><code translate="no" dir="ltr">CoroutineScope</code></a> is bound to <code translate="no" dir="ltr">Dispatchers.Main</code> and is automatically cancelled when the <code translate="no" dir="ltr">ViewModel</code> is cleared. You can use <code translate="no" dir="ltr">viewModelScope()</code> instead of creating a new scope for each <code translate="no" dir="ltr">ViewModel</code>.</p> <p>To include this module, add the following to your app&#39;s <code translate="no" dir="ltr">build.gradle</code> file:</p> <div> <div class="ds-selector-tabs"><section><h3 id="groovy" data-text="Groovy" tabindex="-1">Groovy</h3> <div></div><devsite-code><pre class="devsite-click-to-copy" translate="no" dir="ltr" is-upgraded syntax="Groovy"><span class="devsite-syntax-n">dependencies</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-o">{</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">implementation</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-s2">"androidx.lifecycle:lifecycle-viewmodel-ktx:2.8.7"</span> <span class="devsite-syntax-o">}</span></pre></devsite-code> </section><section><h3 id="kts" data-text="Kotlin" tabindex="-1">Kotlin</h3> <div></div><devsite-code><pre class="devsite-click-to-copy" translate="no" dir="ltr" is-upgraded syntax="Kotlin"><span class="devsite-syntax-n">dependencies</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">{</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">implementation</span><span class="devsite-syntax-p">(</span><span class="devsite-syntax-s">"androidx.lifecycle:lifecycle-viewmodel-ktx:2.8.7"</span><span class="devsite-syntax-p">)</span> <span class="devsite-syntax-p">}</span></pre></devsite-code> </section></div> </div> <p>As an example, the following <code translate="no" dir="ltr">viewModelScope()</code> function launches a coroutine that makes a network request in a background thread. The library handles all of the setup and corresponding scope clearing:</p> <div></div><devsite-code><pre class="devsite-click-to-copy" translate="no" dir="ltr" is-upgraded syntax="Kotlin"><code translate="no" dir="ltr"><span class="devsite-syntax-kd">class</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-nc">MainViewModel</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">:</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">ViewModel</span><span class="devsite-syntax-p">()</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">{</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-c1">// Make a network request without blocking the UI thread</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-kd">private</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-kd">fun</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-nf">makeNetworkRequest</span><span class="devsite-syntax-p">()</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">{</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-c1">// launch a coroutine in viewModelScope</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">viewModelScope</span><span class="devsite-syntax-p">.</span><span class="devsite-syntax-na">launch</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">{</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">remoteApi</span><span class="devsite-syntax-p">.</span><span class="devsite-syntax-na">slowFetch</span><span class="devsite-syntax-p">()</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">...</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">}</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">}</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-c1">// No need to override onCleared()</span> <span class="devsite-syntax-p">}</span> </code></pre></devsite-code> <h3 id="workmanager" data-text="WorkManager KTX" tabindex="-1">WorkManager KTX</h3> <p>WorkManager KTX provides first-class support for coroutines.</p> <p>To include this module, add the following to your app&#39;s <code translate="no" dir="ltr">build.gradle</code> file:</p> <div> <div class="ds-selector-tabs"><section><h3 id="groovy" data-text="Groovy" tabindex="-1">Groovy</h3> <div></div><devsite-code><pre class="devsite-click-to-copy" translate="no" dir="ltr" is-upgraded syntax="Groovy"><span class="devsite-syntax-n">dependencies</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-o">{</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">implementation</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-s2">"androidx.work:work-runtime-ktx:2.9.1"</span> <span class="devsite-syntax-o">}</span></pre></devsite-code> </section><section><h3 id="kts" data-text="Kotlin" tabindex="-1">Kotlin</h3> <div></div><devsite-code><pre class="devsite-click-to-copy" translate="no" dir="ltr" is-upgraded syntax="Kotlin"><span class="devsite-syntax-n">dependencies</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">{</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">implementation</span><span class="devsite-syntax-p">(</span><span class="devsite-syntax-s">"androidx.work:work-runtime-ktx:2.9.1"</span><span class="devsite-syntax-p">)</span> <span class="devsite-syntax-p">}</span></pre></devsite-code> </section></div> </div> <p>Instead of extending <a href="/reference/androidx/work/Worker"><code translate="no" dir="ltr">Worker</code></a>, you can now extend <a href="/reference/kotlin/androidx/work/CoroutineWorker"><code translate="no" dir="ltr">CoroutineWorker</code></a>, which has a slightly different API. For example, if you wanted to build a simple <code translate="no" dir="ltr">CoroutineWorker</code> to perform some network operations, you can do the following:</p> <div></div><devsite-code><pre class="devsite-click-to-copy" translate="no" dir="ltr" is-upgraded syntax="Kotlin"><code translate="no" dir="ltr"><span class="devsite-syntax-kd">class</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-nc">CoroutineDownloadWorker</span><span class="devsite-syntax-p">(</span><span class="devsite-syntax-n">context</span><span class="devsite-syntax-p">:</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">Context</span><span class="devsite-syntax-p">,</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">params</span><span class="devsite-syntax-p">:</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">WorkerParameters</span><span class="devsite-syntax-p">)</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">:</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">CoroutineWorker</span><span class="devsite-syntax-p">(</span><span class="devsite-syntax-n">context</span><span class="devsite-syntax-p">,</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">params</span><span class="devsite-syntax-p">)</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">{</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-kd">override</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-kd">suspend</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-kd">fun</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-nf">doWork</span><span class="devsite-syntax-p">():</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">Result</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-o">=</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">coroutineScope</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">{</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-kd">val</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-nv">jobs</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-o">=</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">(</span><span class="devsite-syntax-m">0</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">until</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-m">100</span><span class="devsite-syntax-p">).</span><span class="devsite-syntax-na">map</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">{</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">async</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">{</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">downloadSynchronously</span><span class="devsite-syntax-p">(</span><span class="devsite-syntax-s">"https://www.google.com"</span><span class="devsite-syntax-p">)</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">}</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">}</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-c1">// awaitAll will throw an exception if a download fails, which</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-c1">// CoroutineWorker will treat as a failure</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">jobs</span><span class="devsite-syntax-p">.</span><span class="devsite-syntax-na">awaitAll</span><span class="devsite-syntax-p">()</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">Result</span><span class="devsite-syntax-p">.</span><span class="devsite-syntax-na">success</span><span class="devsite-syntax-p">()</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">}</span> <span class="devsite-syntax-p">}</span> </code></pre></devsite-code> <p>For more information on using <code translate="no" dir="ltr">CoroutineWorker</code>, see <a href="/topic/libraries/architecture/workmanager/advanced/coroutineworker">Threading in CoroutineWorker</a>.</p> <p>WorkManager KTX also adds extension functions to <code translate="no" dir="ltr">Operations</code> and <code translate="no" dir="ltr">ListenableFutures</code> to suspend the current coroutine.</p> <p>Here&#39;s an example that suspends the <a href="/reference/androidx/work/Operation"><code translate="no" dir="ltr">Operation</code></a> that&#39;s returned by <a href="/reference/androidx/work/WorkContinuation#enqueue()"><code translate="no" dir="ltr">enqueue()</code></a>:</p> <div></div><devsite-code><pre class="devsite-click-to-copy" translate="no" dir="ltr" is-upgraded syntax="Kotlin"><code translate="no" dir="ltr"><span class="devsite-syntax-c1">// Inside of a coroutine...</span> <span class="devsite-syntax-c1">// Run async operation and suspend until completed.</span> <span class="devsite-syntax-n">WorkManager</span><span class="devsite-syntax-p">.</span><span class="devsite-syntax-na">getInstance</span><span class="devsite-syntax-p">()</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">.</span><span class="devsite-syntax-na">beginWith</span><span class="devsite-syntax-p">(</span><span class="devsite-syntax-n">longWorkRequest</span><span class="devsite-syntax-p">)</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">.</span><span class="devsite-syntax-na">enqueue</span><span class="devsite-syntax-p">().</span><span class="devsite-syntax-na">await</span><span class="devsite-syntax-p">()</span> <span class="devsite-syntax-c1">// Resume after work completes...</span> </code></pre></devsite-code> <h2 id="other" data-text="Other KTX modules" tabindex="-1">Other KTX modules</h2> <p>You can also include additional KTX modules that exist outside of AndroidX.</p> <h3 id="firebase" data-text="Firebase KTX" tabindex="-1">Firebase KTX</h3> <p>Some of the Firebase SDKs for Android have Kotlin extension libraries that enable you to write idiomatic Kotlin code when using Firebase in your app. For more information, see the following topics:</p> <ul> <li><a href="https://firebaseopensource.com/projects/firebase/firebase-android-sdk#kotlin_extensions">Firebase Android SDK</a></li> <li><a href="https://github.com/firebase/firebase-android-sdk/blob/master/docs/ktx/common.md">Firebase Common Kotlin Extensions</a></li> </ul> <h3 id="google-maps-platform" data-text="Google Maps Platform KTX" tabindex="-1">Google Maps Platform KTX</h3> <p>There are KTX extensions available for Google Maps Platform Android SDKs which allow you to take advantage of several Kotlin language features such as extension functions, named parameters and default arguments, destructuring declarations, and coroutines. For more information, see the following topics:</p> <ul> <li><a href="https://developers.google.com/maps/documentation/android-sdk/ktx">Maps Android KTX</a></li> <li><a href="https://developers.google.com/places/android-sdk/ktx">Places Android KTX</a></li> </ul> <h3 id="play-core" data-text="Play Core KTX" tabindex="-1">Play Core KTX</h3> <p>Play Core KTX adds support for Kotlin coroutines for one-shot requests and Flow for monitoring status updates by adding extension functions to <code translate="no" dir="ltr">SplitInstallManager</code> and <code translate="no" dir="ltr">AppUpdateManager</code> in the Play Core library.</p> <p>To include this module, add the following to your app&#39;s <code translate="no" dir="ltr">build.gradle</code> file:</p> <div> <div class="ds-selector-tabs"><section><h3 id="groovy" data-text="Groovy" tabindex="-1">Groovy</h3> <div></div><devsite-code><pre class="devsite-click-to-copy" translate="no" dir="ltr" is-upgraded syntax="Groovy"><span class="devsite-syntax-n">dependencies</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-o">{</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">implementation</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-s2">"com.google.android.play:core-ktx:1.8.1"</span> <span class="devsite-syntax-o">}</span></pre></devsite-code> </section><section><h3 id="kts" data-text="Kotlin" tabindex="-1">Kotlin</h3> <div></div><devsite-code><pre class="devsite-click-to-copy" translate="no" dir="ltr" is-upgraded syntax="Kotlin"><span class="devsite-syntax-n">dependencies</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">{</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">implementation</span><span class="devsite-syntax-p">(</span><span class="devsite-syntax-s">"com.google.android.play:core-ktx:1.8.1"</span><span class="devsite-syntax-p">)</span> <span class="devsite-syntax-p">}</span></pre></devsite-code> </section></div> </div> <p>Here&#39;s an example of a status-monitoring <code translate="no" dir="ltr">Flow</code>:</p> <div></div><devsite-code><pre class="devsite-click-to-copy" translate="no" dir="ltr" is-upgraded syntax="Kotlin"><code translate="no" dir="ltr"><span class="devsite-syntax-c1">// Inside of a coroutine...</span> <span class="devsite-syntax-c1">// Request in-app update status updates.</span> <span class="devsite-syntax-n">manager</span><span class="devsite-syntax-p">.</span><span class="devsite-syntax-na">requestUpdateFlow</span><span class="devsite-syntax-p">().</span><span class="devsite-syntax-na">collect</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">{</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">updateResult</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-o">-</span>&gt; <span class="devsite-syntax-w"> </span><span class="devsite-syntax-k">when</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">(</span><span class="devsite-syntax-n">updateResult</span><span class="devsite-syntax-p">)</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">{</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-k">is</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">AppUpdateResult</span><span class="devsite-syntax-p">.</span><span class="devsite-syntax-na">Available</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-o">-</span>&gt;<span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">TODO</span><span class="devsite-syntax-p">()</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-k">is</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">AppUpdateResult</span><span class="devsite-syntax-p">.</span><span class="devsite-syntax-na">InProgress</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-o">-</span>&gt;<span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">TODO</span><span class="devsite-syntax-p">()</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-k">is</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">AppUpdateResult</span><span class="devsite-syntax-p">.</span><span class="devsite-syntax-na">Downloaded</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-o">-</span>&gt;<span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">TODO</span><span class="devsite-syntax-p">()</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">AppUpdateResult</span><span class="devsite-syntax-p">.</span><span class="devsite-syntax-na">NotAvailable</span><span class="devsite-syntax-w"> </span><span class="devsite-syntax-o">-</span>&gt;<span class="devsite-syntax-w"> </span><span class="devsite-syntax-n">TODO</span><span class="devsite-syntax-p">()</span> <span class="devsite-syntax-w"> </span><span class="devsite-syntax-p">}</span> <span class="devsite-syntax-p">}</span> </code></pre></devsite-code> <h2 id="more" data-text="More information" tabindex="-1">More information</h2> <p>To learn more about Android KTX, see the <a href="https://www.youtube.com/watch?v=r_19VZ0xRO8&amp;feature=youtu.be" class="external">DevBytes video</a>.</p> <p>To report an issue or suggest a feature, use the <a href="https://issuetracker.google.com/issues/new?component=396204&amp;template=1082185">Android KTX issue tracker</a>.</p> <devsite-hats-survey class="nocontent" hats-id="VxqvKSur40kxBYCLVTd0SSGykbno" listnr-id="5207477"></devsite-hats-survey> </div> <devsite-recommendations display="in-page" hidden yield> </devsite-recommendations> <devsite-thumb-rating position="footer"> </devsite-thumb-rating> <devsite-recommendations id="recommendations-link" yield></devsite-recommendations> <div class="devsite-floating-action-buttons"> </div> </article> <devsite-content-footer class="nocontent"> <p>Content and code samples on this page are subject to the licenses described in the <a href="/license">Content License</a>. 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