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repositories</span></div></a></li></ul></li><li class="nav-item"><a class="nav-link" href="/tools/pub/private-files"><div><span>What not to commit</span></div></a></li></ul></li><li class="nav-item"><button class="nav-link collapsed collapsible" data-toggle="collapse" data-target="#-sidenav-5" role="button" aria-expanded="false" aria-controls="-sidenav-5"><span>Development</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="-sidenav-5"><li class="nav-item"><a class="nav-link" href="/libraries/serialization/json"><div><span>JSON serialization</span></div></a></li><li class="nav-item"><a class="nav-link" href="/resources/language/number-representation"><div><span>Number representation</span></div></a></li><li class="nav-item"><a class="nav-link" href="/resources/google-apis"><div><span>Google APIs</span></div></a></li><li class="nav-item"><a class="nav-link" href="/multiplatform-apps"><div><span>Multi-platform apps</span></div></a></li><li class="nav-item"><button class="nav-link collapsible collapsed" data-toggle="collapse" data-target="#-sidenav-5-5" role="button" aria-expanded="false" aria-controls="-sidenav-5-5"><span>Command-line & server apps</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="-sidenav-5-5"><li class="nav-item"><a class="nav-link" href="/server"><div><span>Overview</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tutorials/server/get-started"><div><span>Get started</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tutorials/server/cmdline"><div><span>Write command-line apps</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tutorials/server/fetch-data"><div><span>Fetch data from the internet</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tutorials/server/httpserver"><div><span>Write HTTP servers</span></div></a></li><li 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class="site-toc__title">Contents</header><ul class="section-nav"><li class="toc-entry nav-item"><a class="nav-link" href="#simple-java-example">Simple Java example</a><ul class="nav"><li class="toc-entry nav-item"><a class="nav-link" href="#prerequisites">Prerequisites</a></li><li class="toc-entry nav-item"><a class="nav-link" href="#configure-jnigen">Configure jnigen</a></li><li class="toc-entry nav-item"><a class="nav-link" href="#generate-the-dart-bindings">Generate the Dart bindings</a></li><li class="toc-entry nav-item"><a class="nav-link" href="#use-the-bindings">Use the bindings</a></li><li class="toc-entry nav-item"><a class="nav-link" href="#run-the-example">Run the example</a></li></ul></li><li class="toc-entry nav-item"><a class="nav-link" href="#more-examples">More examples</a></li></ul></div><article><div class="content"><div id="site-content-title"><h1>Java interop using package:jnigen</h1></div><div id="site-toc--inline" class="site-toc"><header class="site-toc__title">Contents</header><ul class="section-nav"><li class="toc-entry"><a href="#simple-java-example">Simple Java example</a><ul><li class="toc-entry"><a href="#prerequisites">Prerequisites</a></li><li class="toc-entry"><a href="#configure-jnigen">Configure jnigen</a></li><li class="toc-entry"><a href="#generate-the-dart-bindings">Generate the Dart bindings</a></li><li class="toc-entry"><a href="#use-the-bindings">Use the bindings</a></li><li class="toc-entry"><a href="#run-the-example">Run the example</a></li></ul></li><li class="toc-entry"><a href="#more-examples">More examples</a></li></ul></div><p>Dart mobile, command-line, and server apps running on the <a href="/overview#platform">Dart Native platform</a>, on Android, Windows, macOS, and Linux can use <a href="https://pub.dev/packages/jni"><code>package:jni</code></a> and <a href="https://pub.dev/packages/jnigen"><code>package:jnigen</code></a> to call Java and Kotlin APIs.</p><aside class="alert alert-info"><div class="alert-header"><span class="material-symbols" aria-hidden="true">info</span> <span>Note</span></div><div class="alert-content"><p>This interop feature is <strong>experimental</strong>, and <a href="https://github.com/dart-lang/sdk/issues/49674">in active development</a>.</p></div></aside><p><code>package:jni</code> allows Dart code to interact with Java through <a href="https://docs.oracle.com/en/java/javase/17/docs/specs/jni/index.html">JNI</a>. However, doing so involves a lot of boilerplate code, so you can use <code>package:jnigen</code> to automatically generate the Dart bindings for a given Java API.</p><p>You can compile Kotlin to Java bytecode, allowing <code>package:jnigen</code> to generate bindings for Kotlin as well.</p><div class="header-wrapper"><h2 id="simple-java-example">Simple Java example</h2><a class="heading-link" href="#simple-java-example" aria-label="Link to 'Simple Java example' section">#</a></div><p>This guide walks you through <a href="https://github.com/HosseinYousefi/jnigen_example/tree/main">an example</a> that uses <code>package:jnigen</code> to generate bindings for a simple class.</p><div class="header-wrapper"><h3 id="prerequisites">Prerequisites</h3><a class="heading-link" href="#prerequisites" aria-label="Link to 'Prerequisites' section">#</a></div><ul><li>JDK</li><li><a href="https://maven.apache.org/">Maven</a></li></ul><div class="header-wrapper"><h3 id="configure-jnigen">Configure <code>jnigen</code></h3><a class="heading-link" href="#configure-jnigen" aria-label="Link to 'Configure jnigen' section">#</a></div><p>First, add <code>package:jni</code> as a dependency and <code>package:jnigen</code> as a <a href="/tools/pub/dependencies#dev-dependencies">dev dependency</a>.</p><div class="code-block-wrapper language-console"><div class="code-block-body"><pre class="shiki dash-light" tabindex="0"><code><span class="line"><span style="color:#222222">$ dart pub add jni dev:jnigen</span></span></code></pre></div></div><p>Next, create a top-level file called <code>jnigen.yaml</code>. This file contains the configuration for generating the bindings.</p><div class="code-block-wrapper language-yaml"><div class="code-block-body"><span class="code-block-language" title="Language yaml">yaml</span><pre class="shiki dash-light" tabindex="0"><code><span class="line"><span style="color:#0468D7">output</span><span style="color:#222222">:</span></span> <span class="line"><span style="color:#0468D7"> dart</span><span style="color:#222222">:</span></span> <span class="line"><span style="color:#0468D7"> path</span><span style="color:#222222">: </span><span style="color:#11796D">lib/example.dart</span></span> <span class="line"><span style="color:#0468D7"> structure</span><span style="color:#222222">: </span><span style="color:#11796D">single_file</span></span> <span class="line"></span> <span class="line"><span style="color:#0468D7">source_path</span><span style="color:#222222">:</span></span> <span class="line"><span style="color:#222222"> - </span><span style="color:#11796D">'java/'</span></span> <span class="line"><span style="color:#0468D7">classes</span><span style="color:#222222">:</span></span> <span class="line"><span style="color:#222222"> - </span><span style="color:#11796D">'dev.dart.Example'</span></span></code></pre></div></div><p><code>path</code> specifies the path for the generated <code>dart</code> bindings.</p><p><code>source_path</code> specifies the path of the Java source file that you want to generate bindings for, and <code>classes</code> specifies the Java class.</p><p><code>java/dev/dart/Example.java</code> contains a very simple class, which has a public static method called <code>sum</code>:</p><div class="code-block-wrapper language-java"><div class="code-block-body"><span class="code-block-language" title="Language java">java</span><pre class="shiki dash-light" tabindex="0"><code><span class="line"><span style="color:#D43324">package</span><span style="color:#222222"> dev.dart;</span></span> <span class="line"></span> <span class="line"><span style="color:#D43324">public</span><span style="color:#D43324"> class</span><span style="color:#0468D7"> Example</span><span style="color:#222222"> {</span></span> <span class="line"><span style="color:#D43324"> public</span><span style="color:#D43324"> static</span><span style="color:#D43324"> int</span><span style="color:#6200EE"> sum</span><span style="color:#222222">(</span><span style="color:#D43324">int</span><span style="color:#222222"> a, </span><span style="color:#D43324">int</span><span style="color:#222222"> b) {</span></span> <span class="line"><span style="color:#D43324"> return</span><span style="color:#222222"> a + b;</span></span> <span class="line"><span style="color:#222222"> }</span></span> <span class="line"><span style="color:#222222">}</span></span></code></pre></div></div><div class="header-wrapper"><h3 id="generate-the-dart-bindings">Generate the Dart bindings</h3><a class="heading-link" href="#generate-the-dart-bindings" aria-label="Link to 'Generate the Dart bindings' section">#</a></div><p>To generate the Dart bindings, run <code>jnigen</code> and specify the config file using the <code>--config</code> option:</p><div class="code-block-wrapper language-console"><div class="code-block-body"><pre class="shiki dash-light" tabindex="0"><code><span class="line"><span style="color:#222222">$ dart run jnigen --config jnigen.yaml</span></span></code></pre></div></div><p>In this example, this generates <a href="https://github.com/HosseinYousefi/jnigen_example/tree/main/lib/example.dart">lib/example.dart</a>, just as you specified in <code>jnigen.yaml</code>.</p><p>This file contains a class called <code>Example</code>, which has a static method called <code>sum</code>, just like the Java file.</p><div class="header-wrapper"><h3 id="use-the-bindings">Use the bindings</h3><a class="heading-link" href="#use-the-bindings" aria-label="Link to 'Use the bindings' section">#</a></div><p>Now you're ready to load and interact with the generated library. The example app, <a href="https://github.com/HosseinYousefi/jnigen_example/tree/main/bin/sum.dart">bin/sum.dart</a>, gets two numbers as arguments and prints their sum. Using the <code>Example.sum</code> method is identical to Java.</p><div class="code-block-wrapper language-dart"><div class="code-block-body"><span class="code-block-language" title="Language dart">dart</span><pre class="shiki dash-light" tabindex="0"><code><span class="line"><span style="color:#6E6E70">// a and b are integer arguments</span></span> <span class="line"><span style="color:#6200EE">print</span><span style="color:#222222">(</span><span style="color:#0468D7">Example</span><span style="color:#222222">.</span><span style="color:#6200EE">sum</span><span style="color:#222222">(a, b));</span></span></code></pre></div></div><div class="header-wrapper"><h3 id="run-the-example">Run the example</h3><a class="heading-link" href="#run-the-example" aria-label="Link to 'Run the example' section">#</a></div><p>Before running the example, you must build the dynamic library for <code>jni</code>. The Java sources also must be compiled. To do so, run:</p><div class="code-block-wrapper language-console"><div class="code-block-body"><pre class="shiki dash-light" tabindex="0"><code><span class="line"><span style="color:#222222">$ dart run jni:setup</span></span> <span class="line"><span style="color:#222222">$ javac java/dev/dart/Example.java</span></span></code></pre></div></div><p>Now you can run the example:</p><div class="code-block-wrapper language-console"><div class="code-block-body"><pre class="shiki dash-light" tabindex="0"><code><span class="line"><span style="color:#222222">$ dart run jnigen_example:sum 17 25</span></span></code></pre></div></div><p>Which outputs <code>42</code>!</p><div class="header-wrapper"><h2 id="more-examples">More examples</h2><a class="heading-link" href="#more-examples" aria-label="Link to 'More examples' section">#</a></div><p>The following are some more comprehensive examples of using <code>package:jnigen</code>:</p><div class="table-wrapper"><table class="table"><thead><tr><th><strong>Example</strong></th><th><strong>Description</strong></th></tr></thead><tbody><tr><td><a href="https://github.com/dart-lang/native/tree/main/pkgs/jnigen/example/in_app_java">in_app_java</a></td><td>Demonstrates how to include custom Java code in a Flutter application and call it use <code>jnigen</code>.</td></tr><tr><td><a href="https://github.com/dart-lang/native/tree/main/pkgs/jnigen/example/pdfbox_plugin">pdfbox_plugin</a></td><td>Example of a Flutter plugin that provides bindings to the <a href="https://pdfbox.apache.org/">Apache PDFBox</a> library.</td></tr><tr><td><a href="https://github.com/dart-lang/native/tree/main/pkgs/jnigen/example/notification_plugin">notification_plugin</a></td><td>Example of a reusable Flutter plugin with custom Java code that uses Android libraries.</td></tr></tbody></table></div><p id="page-github-links"><span>Unless stated otherwise, the documentation on this site reflects Dart 3.7.2. 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