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<script src="https://snack.expo.io/embed.js" defer="defer"></script><title data-react-helmet="true">Headless JS · React Native</title><meta data-react-helmet="true" property="twitter:image" content="https://reactnative.dev/img/logo-og.png"><meta data-react-helmet="true" name="twitter:image:alt" content="Image for React Native"><meta data-react-helmet="true" name="docsearch:language" content="en"><meta data-react-helmet="true" name="docsearch:version" content="current"><meta data-react-helmet="true" name="docsearch:docusaurus_tag" content="docs-default-current"><meta data-react-helmet="true" property="og:image" content="https://reactnative.dev/img/logo-og.png"><meta data-react-helmet="true" name="twitter:card" content="summary"><meta data-react-helmet="true" name="twitter:image" content="https://reactnative.dev/img/logo-og.png"><meta data-react-helmet="true" property="og:title" content="Headless JS · React Native"><meta data-react-helmet="true" name="description" content="Headless JS is a way to run tasks in JavaScript while your app is in the background. It can be used, for example, to sync fresh data, handle push notifications, or play music."><meta data-react-helmet="true" property="og:description" content="Headless JS is a way to run tasks in JavaScript while your app is in the background. It can be used, for example, to sync fresh data, handle push notifications, or play music."><meta data-react-helmet="true" property="og:url" content="https://reactnative.dev/docs/next/headless-js-android"><link data-react-helmet="true" rel="shortcut icon" href="/img/favicon.ico"><link data-react-helmet="true" rel="preconnect" href="https://BH4D9OD16A-dsn.algolia.net" crossorigin="anonymous"><link data-react-helmet="true" rel="canonical" href="https://reactnative.dev/docs/next/headless-js-android"><link rel="stylesheet" href="/styles.fccefeba.css">
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Setup</a></li></ul></li><li class="menu__list-item menu__list-item--collapsed"><a class="menu__link menu__link--sublist" href="#!">Native Components</a><ul class="menu__list"><li class="menu__list-item"><a class="menu__link" tabindex="-1" href="/docs/next/native-components-android">Android Native UI Components</a></li><li class="menu__list-item"><a class="menu__link" tabindex="-1" href="/docs/next/native-components-ios">iOS Native UI Components</a></li><li class="menu__list-item"><a class="menu__link" tabindex="-1" href="/docs/next/direct-manipulation">Direct Manipulation</a></li></ul></li><li class="menu__list-item"><a class="menu__link menu__link--sublist menu__link--active" href="#!">Guides (Android)</a><ul class="menu__list"><li class="menu__list-item"><a aria-current="page" class="menu__link menu__link--active active" tabindex="0" href="/docs/next/headless-js-android">Headless JS</a></li><li class="menu__list-item"><a class="menu__link" tabindex="0" href="/docs/next/signed-apk-android">Publishing to Google Play Store</a></li></ul></li><li class="menu__list-item menu__list-item--collapsed"><a class="menu__link menu__link--sublist" href="#!">Guides (iOS)</a><ul class="menu__list"><li class="menu__list-item"><a class="menu__link" tabindex="-1" href="/docs/next/linking-libraries-ios">Linking Libraries</a></li><li class="menu__list-item"><a class="menu__link" tabindex="-1" href="/docs/next/running-on-simulator-ios">Running On Simulator</a></li><li class="menu__list-item"><a class="menu__link" tabindex="-1" href="/docs/next/communication-ios">Communication between native and React Native</a></li><li class="menu__list-item"><a class="menu__link" tabindex="-1" href="/docs/next/app-extensions">App Extensions</a></li><li class="menu__list-item"><a class="menu__link" tabindex="-1" href="/docs/next/publishing-to-app-store">Publishing to Apple App Store</a></li></ul></li></ul></div></div></div><main class="docMainContainer_1rYT"><div class="container padding-vert--lg docItemWrapper_1Hme"><div class="row"><div class="col docItemCol_2AGf"><div class="alert alert--warning margin-bottom--md" role="alert"><div>This is unreleased documentation for React Native <strong>Next</strong> version.</div><div class="margin-top--md">For up-to-date documentation, see the <strong><a href="/docs/headless-js-android">latest version</a></strong> (0.63).</div></div><div class="docItemContainer_1tAC"><article><div><span class="badge badge--secondary">Version: Next</span></div><header><h1 class="docTitle_cWlf">Headless JS</h1></header><div class="markdown"><p>Headless JS is a way to run tasks in JavaScript while your app is in the background. It can be used, for example, to sync fresh data, handle push notifications, or play music.</p><h2><a aria-hidden="true" tabindex="-1" class="anchor enhancedAnchor_3pqN" id="the-js-api"></a>The JS API<a aria-hidden="true" tabindex="-1" class="hash-link" href="#the-js-api" title="Direct link to heading">#</a></h2><p>A task is an async function that you register on <code>AppRegistry</code>, similar to registering React applications:</p><div class="mdxCodeBlock_xYIz"><div class="codeBlockContent_rlEb"><button tabindex="0" type="button" aria-label="Copy code to clipboard" class="copyButton_kOW4">Copy</button><div class="prism-code language-jsx codeBlock_1AP7"><div class="codeBlockLines_1boI" style="color:#FFFFFF;background:#282C34"><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token keyword" style="color:#c5a5c5">import</span><span class="token plain"> </span><span class="token punctuation" style="color:#657b83">{</span><span class="token plain"> AppRegistry </span><span class="token punctuation" style="color:#657b83">}</span><span class="token plain"> </span><span class="token keyword" style="color:#c5a5c5">from</span><span class="token plain"> </span><span class="token string" style="color:#8dc891">'react-native'</span><span class="token punctuation" style="color:#657b83">;</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain">AppRegistry</span><span class="token punctuation" style="color:#657b83">.</span><span class="token function" style="color:#79b6f2">registerHeadlessTask</span><span class="token punctuation" style="color:#657b83">(</span><span class="token string" style="color:#8dc891">'SomeTaskName'</span><span class="token punctuation" style="color:#657b83">,</span><span class="token plain"> </span><span class="token punctuation" style="color:#657b83">(</span><span class="token punctuation" style="color:#657b83">)</span><span class="token plain"> </span><span class="token operator" style="color:#fc929e">=></span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> </span><span class="token function" style="color:#79b6f2">require</span><span class="token punctuation" style="color:#657b83">(</span><span class="token string" style="color:#8dc891">'SomeTaskName'</span><span class="token punctuation" style="color:#657b83">)</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"></span><span class="token punctuation" style="color:#657b83">)</span><span class="token punctuation" style="color:#657b83">;</span></div></div></div></div></div><p>Then, in <code>SomeTaskName.js</code>:</p><div class="mdxCodeBlock_xYIz"><div class="codeBlockContent_rlEb"><button tabindex="0" type="button" aria-label="Copy code to clipboard" class="copyButton_kOW4">Copy</button><div class="prism-code language-jsx codeBlock_1AP7"><div class="codeBlockLines_1boI" style="color:#FFFFFF;background:#282C34"><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain">module</span><span class="token punctuation" style="color:#657b83">.</span><span class="token function-variable function" style="color:#79b6f2">exports</span><span class="token plain"> </span><span class="token operator" style="color:#fc929e">=</span><span class="token plain"> </span><span class="token keyword" style="color:#c5a5c5">async</span><span class="token plain"> </span><span class="token punctuation" style="color:#657b83">(</span><span class="token parameter">taskData</span><span class="token punctuation" style="color:#657b83">)</span><span class="token plain"> </span><span class="token operator" style="color:#fc929e">=></span><span class="token plain"> </span><span class="token punctuation" style="color:#657b83">{</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> </span><span class="token comment" style="color:#93a1a1">// do stuff</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"></span><span class="token punctuation" style="color:#657b83">}</span><span class="token punctuation" style="color:#657b83">;</span></div></div></div></div></div><p>You can do anything in your task such as network requests, timers and so on, as long as it doesn't touch UI. Once your task completes (i.e. the promise is resolved), React Native will go into "paused" mode (unless there are other tasks running, or there is a foreground app).</p><h2><a aria-hidden="true" tabindex="-1" class="anchor enhancedAnchor_3pqN" id="the-java-api"></a>The Java API<a aria-hidden="true" tabindex="-1" class="hash-link" href="#the-java-api" title="Direct link to heading">#</a></h2><p>Yes, this does still require some native code, but it's pretty thin. You need to extend <code>HeadlessJsTaskService</code> and override <code>getTaskConfig</code>, e.g.:</p><div class="mdxCodeBlock_xYIz"><div class="codeBlockContent_rlEb"><button tabindex="0" type="button" aria-label="Copy code to clipboard" class="copyButton_kOW4">Copy</button><div class="prism-code language-java codeBlock_1AP7"><div class="codeBlockLines_1boI" style="color:#FFFFFF;background:#282C34"><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token keyword" style="color:#c5a5c5">package</span><span class="token plain"> </span><span class="token namespace" style="opacity:0.7">com</span><span class="token namespace punctuation" style="opacity:0.7;color:#657b83">.</span><span class="token namespace" style="opacity:0.7">your_application_name</span><span class="token punctuation" style="color:#657b83">;</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"></span><span class="token keyword" style="color:#c5a5c5">import</span><span class="token plain"> </span><span class="token namespace" style="opacity:0.7">android</span><span class="token namespace punctuation" style="opacity:0.7;color:#657b83">.</span><span class="token namespace" style="opacity:0.7">content</span><span class="token punctuation" style="color:#657b83">.</span><span class="token class-name" style="color:#fac863">Intent</span><span class="token punctuation" style="color:#657b83">;</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"></span><span class="token keyword" style="color:#c5a5c5">import</span><span class="token plain"> </span><span class="token namespace" style="opacity:0.7">android</span><span class="token namespace punctuation" style="opacity:0.7;color:#657b83">.</span><span class="token namespace" style="opacity:0.7">os</span><span class="token punctuation" style="color:#657b83">.</span><span class="token class-name" style="color:#fac863">Bundle</span><span class="token punctuation" style="color:#657b83">;</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"></span><span class="token keyword" style="color:#c5a5c5">import</span><span class="token plain"> </span><span class="token namespace" style="opacity:0.7">com</span><span class="token namespace punctuation" style="opacity:0.7;color:#657b83">.</span><span class="token namespace" style="opacity:0.7">facebook</span><span class="token namespace punctuation" style="opacity:0.7;color:#657b83">.</span><span class="token namespace" style="opacity:0.7">react</span><span class="token punctuation" style="color:#657b83">.</span><span class="token class-name" style="color:#fac863">HeadlessJsTaskService</span><span class="token punctuation" style="color:#657b83">;</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"></span><span class="token keyword" style="color:#c5a5c5">import</span><span class="token plain"> </span><span class="token namespace" style="opacity:0.7">com</span><span class="token namespace punctuation" style="opacity:0.7;color:#657b83">.</span><span class="token namespace" style="opacity:0.7">facebook</span><span class="token namespace punctuation" style="opacity:0.7;color:#657b83">.</span><span class="token namespace" style="opacity:0.7">react</span><span class="token namespace punctuation" style="opacity:0.7;color:#657b83">.</span><span class="token namespace" style="opacity:0.7">bridge</span><span class="token punctuation" style="color:#657b83">.</span><span class="token class-name" style="color:#fac863">Arguments</span><span class="token punctuation" style="color:#657b83">;</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"></span><span class="token keyword" style="color:#c5a5c5">import</span><span class="token plain"> </span><span class="token namespace" style="opacity:0.7">com</span><span class="token namespace punctuation" style="opacity:0.7;color:#657b83">.</span><span class="token namespace" style="opacity:0.7">facebook</span><span class="token namespace punctuation" style="opacity:0.7;color:#657b83">.</span><span class="token namespace" style="opacity:0.7">react</span><span class="token namespace punctuation" style="opacity:0.7;color:#657b83">.</span><span class="token namespace" style="opacity:0.7">jstasks</span><span class="token punctuation" style="color:#657b83">.</span><span class="token class-name" style="color:#fac863">HeadlessJsTaskConfig</span><span class="token punctuation" style="color:#657b83">;</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"></span><span class="token keyword" style="color:#c5a5c5">import</span><span class="token plain"> </span><span class="token namespace" style="opacity:0.7">javax</span><span class="token namespace punctuation" style="opacity:0.7;color:#657b83">.</span><span class="token namespace" style="opacity:0.7">annotation</span><span class="token punctuation" style="color:#657b83">.</span><span class="token class-name" style="color:#fac863">Nullable</span><span class="token punctuation" style="color:#657b83">;</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain" style="display:inline-block">
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</span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"></span><span class="token keyword" style="color:#c5a5c5">public</span><span class="token plain"> </span><span class="token keyword" style="color:#c5a5c5">class</span><span class="token plain"> </span><span class="token class-name" style="color:#fac863">MyTaskService</span><span class="token plain"> </span><span class="token keyword" style="color:#c5a5c5">extends</span><span class="token plain"> </span><span class="token class-name" style="color:#fac863">HeadlessJsTaskService</span><span class="token plain"> </span><span class="token punctuation" style="color:#657b83">{</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain" style="display:inline-block">
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</span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> </span><span class="token annotation punctuation" style="color:#657b83">@Override</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> </span><span class="token keyword" style="color:#c5a5c5">protected</span><span class="token plain"> </span><span class="token annotation punctuation" style="color:#657b83">@Nullable</span><span class="token plain"> </span><span class="token class-name" style="color:#fac863">HeadlessJsTaskConfig</span><span class="token plain"> </span><span class="token function" style="color:#79b6f2">getTaskConfig</span><span class="token punctuation" style="color:#657b83">(</span><span class="token class-name" style="color:#fac863">Intent</span><span class="token plain"> intent</span><span class="token punctuation" style="color:#657b83">)</span><span class="token plain"> </span><span class="token punctuation" style="color:#657b83">{</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> </span><span class="token class-name" style="color:#fac863">Bundle</span><span class="token plain"> extras </span><span class="token operator" style="color:#fc929e">=</span><span class="token plain"> intent</span><span class="token punctuation" style="color:#657b83">.</span><span class="token function" style="color:#79b6f2">getExtras</span><span class="token punctuation" style="color:#657b83">(</span><span class="token punctuation" style="color:#657b83">)</span><span class="token punctuation" style="color:#657b83">;</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> </span><span class="token keyword" style="color:#c5a5c5">if</span><span class="token plain"> </span><span class="token punctuation" style="color:#657b83">(</span><span class="token plain">extras </span><span class="token operator" style="color:#fc929e">!=</span><span class="token plain"> </span><span class="token keyword" style="color:#c5a5c5">null</span><span class="token punctuation" style="color:#657b83">)</span><span class="token plain"> </span><span class="token punctuation" style="color:#657b83">{</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> </span><span class="token keyword" style="color:#c5a5c5">return</span><span class="token plain"> </span><span class="token keyword" style="color:#c5a5c5">new</span><span class="token plain"> </span><span class="token class-name" style="color:#fac863">HeadlessJsTaskConfig</span><span class="token punctuation" style="color:#657b83">(</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> </span><span class="token string" style="color:#8dc891">"SomeTaskName"</span><span class="token punctuation" style="color:#657b83">,</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> </span><span class="token class-name" style="color:#fac863">Arguments</span><span class="token punctuation" style="color:#657b83">.</span><span class="token function" style="color:#79b6f2">fromBundle</span><span class="token punctuation" style="color:#657b83">(</span><span class="token plain">extras</span><span class="token punctuation" style="color:#657b83">)</span><span class="token punctuation" style="color:#657b83">,</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> </span><span class="token number" style="color:#5a9bcf">5000</span><span class="token punctuation" style="color:#657b83">,</span><span class="token plain"> </span><span class="token comment" style="color:#93a1a1">// timeout for the task</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> </span><span class="token boolean" style="color:#ff8b50">false</span><span class="token plain"> </span><span class="token comment" style="color:#93a1a1">// optional: defines whether or not the task is allowed in foreground. Default is false</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> </span><span class="token punctuation" style="color:#657b83">)</span><span class="token punctuation" style="color:#657b83">;</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> </span><span class="token punctuation" style="color:#657b83">}</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> </span><span class="token keyword" style="color:#c5a5c5">return</span><span class="token plain"> </span><span class="token keyword" style="color:#c5a5c5">null</span><span class="token punctuation" style="color:#657b83">;</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> </span><span class="token punctuation" style="color:#657b83">}</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"></span><span class="token punctuation" style="color:#657b83">}</span></div></div></div></div></div><p>Then add the service to your <code>AndroidManifest.xml</code> file:</p><div class="mdxCodeBlock_xYIz"><div class="codeBlockContent_rlEb"><button tabindex="0" type="button" aria-label="Copy code to clipboard" class="copyButton_kOW4">Copy</button><div class="prism-code language-jsx codeBlock_1AP7"><div class="codeBlockLines_1boI" style="color:#FFFFFF;background:#282C34"><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token tag punctuation" style="color:#657b83"><</span><span class="token tag" style="color:#fc929e">service</span><span class="token tag" style="color:#fc929e"> </span><span class="token tag attr-name namespace" style="color:#c5a5c5;opacity:0.7">android:</span><span class="token tag attr-name" style="color:#c5a5c5">name</span><span class="token tag attr-value punctuation" style="color:#657b83">=</span><span class="token tag attr-value punctuation" style="color:#657b83">"</span><span class="token tag attr-value" style="color:#8dc891">com.example.MyTaskService</span><span class="token tag attr-value punctuation" style="color:#657b83">"</span><span class="token tag" style="color:#fc929e"> </span><span class="token tag punctuation" style="color:#657b83">/></span></div></div></div></div></div><p>Now, whenever you <a href="https://developer.android.com/reference/android/content/Context.html#startService(android.content.Intent)" target="_blank" rel="noopener noreferrer">start your service</a>, e.g. as a periodic task or in response to some system event / broadcast, JS will spin up, run your task, then spin down.</p><p>Example:</p><div class="mdxCodeBlock_xYIz"><div class="codeBlockContent_rlEb"><button tabindex="0" type="button" aria-label="Copy code to clipboard" class="copyButton_kOW4">Copy</button><div class="prism-code language-java codeBlock_1AP7"><div class="codeBlockLines_1boI" style="color:#FFFFFF;background:#282C34"><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token class-name" style="color:#fac863">Intent</span><span class="token plain"> service </span><span class="token operator" style="color:#fc929e">=</span><span class="token plain"> </span><span class="token keyword" style="color:#c5a5c5">new</span><span class="token plain"> </span><span class="token class-name" style="color:#fac863">Intent</span><span class="token punctuation" style="color:#657b83">(</span><span class="token function" style="color:#79b6f2">getApplicationContext</span><span class="token punctuation" style="color:#657b83">(</span><span class="token punctuation" style="color:#657b83">)</span><span class="token punctuation" style="color:#657b83">,</span><span class="token plain"> </span><span class="token class-name" style="color:#fac863">MyTaskService</span><span class="token punctuation" style="color:#657b83">.</span><span class="token keyword" style="color:#c5a5c5">class</span><span class="token punctuation" style="color:#657b83">)</span><span class="token punctuation" style="color:#657b83">;</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"></span><span class="token class-name" style="color:#fac863">Bundle</span><span class="token plain"> bundle </span><span class="token operator" style="color:#fc929e">=</span><span class="token plain"> </span><span class="token keyword" style="color:#c5a5c5">new</span><span class="token plain"> </span><span class="token class-name" style="color:#fac863">Bundle</span><span class="token punctuation" style="color:#657b83">(</span><span class="token punctuation" style="color:#657b83">)</span><span class="token punctuation" style="color:#657b83">;</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain" style="display:inline-block">
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</span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain">bundle</span><span class="token punctuation" style="color:#657b83">.</span><span class="token function" style="color:#79b6f2">putString</span><span class="token punctuation" style="color:#657b83">(</span><span class="token string" style="color:#8dc891">"foo"</span><span class="token punctuation" style="color:#657b83">,</span><span class="token plain"> </span><span class="token string" style="color:#8dc891">"bar"</span><span class="token punctuation" style="color:#657b83">)</span><span class="token punctuation" style="color:#657b83">;</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain">service</span><span class="token punctuation" style="color:#657b83">.</span><span class="token function" style="color:#79b6f2">putExtras</span><span class="token punctuation" style="color:#657b83">(</span><span class="token plain">bundle</span><span class="token punctuation" style="color:#657b83">)</span><span class="token punctuation" style="color:#657b83">;</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain" style="display:inline-block">
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</span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"></span><span class="token function" style="color:#79b6f2">getApplicationContext</span><span class="token punctuation" style="color:#657b83">(</span><span class="token punctuation" style="color:#657b83">)</span><span class="token punctuation" style="color:#657b83">.</span><span class="token function" style="color:#79b6f2">startService</span><span class="token punctuation" style="color:#657b83">(</span><span class="token plain">service</span><span class="token punctuation" style="color:#657b83">)</span><span class="token punctuation" style="color:#657b83">;</span></div></div></div></div></div><h2><a aria-hidden="true" tabindex="-1" class="anchor enhancedAnchor_3pqN" id="retries"></a>Retries<a aria-hidden="true" tabindex="-1" class="hash-link" href="#retries" title="Direct link to heading">#</a></h2><p>By default, the headless JS task will not perform any retries. In order to do so, you need to create a <code>HeadlessJsRetryPolicy</code> and throw a specific <code>Error</code>.</p><p><code>LinearCountingRetryPolicy</code> is an implementation of <code>HeadlessJsRetryPolicy</code> that allows you to specify a maximum number of retries with a fixed delay between each attempt. If that does not suit your needs then you can implement your own <code>HeadlessJsRetryPolicy</code>. These policies can be passed as an extra argument to the <code>HeadlessJsTaskConfig</code> constructor, e.g.</p><div class="mdxCodeBlock_xYIz"><div class="codeBlockContent_rlEb"><button tabindex="0" type="button" aria-label="Copy code to clipboard" class="copyButton_kOW4">Copy</button><div class="prism-code language-java codeBlock_1AP7"><div class="codeBlockLines_1boI" style="color:#FFFFFF;background:#282C34"><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token class-name" style="color:#fac863">HeadlessJsRetryPolicy</span><span class="token plain"> retryPolicy </span><span class="token operator" style="color:#fc929e">=</span><span class="token plain"> </span><span class="token keyword" style="color:#c5a5c5">new</span><span class="token plain"> </span><span class="token class-name" style="color:#fac863">LinearCountingRetryPolicy</span><span class="token punctuation" style="color:#657b83">(</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> </span><span class="token number" style="color:#5a9bcf">3</span><span class="token punctuation" style="color:#657b83">,</span><span class="token plain"> </span><span class="token comment" style="color:#93a1a1">// Max number of retry attempts</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> </span><span class="token number" style="color:#5a9bcf">1000</span><span class="token plain"> </span><span class="token comment" style="color:#93a1a1">// Delay between each retry attempt</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"></span><span class="token punctuation" style="color:#657b83">)</span><span class="token punctuation" style="color:#657b83">;</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain" style="display:inline-block">
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</span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"></span><span class="token keyword" style="color:#c5a5c5">return</span><span class="token plain"> </span><span class="token keyword" style="color:#c5a5c5">new</span><span class="token plain"> </span><span class="token class-name" style="color:#fac863">HeadlessJsTaskConfig</span><span class="token punctuation" style="color:#657b83">(</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> </span><span class="token string" style="color:#8dc891">'SomeTaskName'</span><span class="token punctuation" style="color:#657b83">,</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> </span><span class="token class-name" style="color:#fac863">Arguments</span><span class="token punctuation" style="color:#657b83">.</span><span class="token function" style="color:#79b6f2">fromBundle</span><span class="token punctuation" style="color:#657b83">(</span><span class="token plain">extras</span><span class="token punctuation" style="color:#657b83">)</span><span class="token punctuation" style="color:#657b83">,</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> </span><span class="token number" style="color:#5a9bcf">5000</span><span class="token punctuation" style="color:#657b83">,</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> </span><span class="token boolean" style="color:#ff8b50">false</span><span class="token punctuation" style="color:#657b83">,</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> retryPolicy</span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"></span><span class="token punctuation" style="color:#657b83">)</span><span class="token punctuation" style="color:#657b83">;</span></div></div></div></div></div><p>A retry attempt will only be made when a specific <code>Error</code> is thrown. Inside a headless JS task, you can import the error and throw it when a retry attempt is required.</p><p>Example:</p><div class="mdxCodeBlock_xYIz"><div class="codeBlockContent_rlEb"><button tabindex="0" type="button" aria-label="Copy code to clipboard" class="copyButton_kOW4">Copy</button><div class="prism-code language-jsx codeBlock_1AP7"><div class="codeBlockLines_1boI" style="color:#FFFFFF;background:#282C34"><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token keyword" style="color:#c5a5c5">import</span><span class="token plain"> </span><span class="token punctuation" style="color:#657b83">{</span><span class="token plain">HeadlessJsTaskError</span><span class="token punctuation" style="color:#657b83">}</span><span class="token plain"> </span><span class="token keyword" style="color:#c5a5c5">from</span><span class="token plain"> </span><span class="token string" style="color:#8dc891">'HeadlessJsTask'</span><span class="token punctuation" style="color:#657b83">;</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain" style="display:inline-block">
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</span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain">module</span><span class="token punctuation" style="color:#657b83">.</span><span class="token function-variable function" style="color:#79b6f2">exports</span><span class="token plain"> </span><span class="token operator" style="color:#fc929e">=</span><span class="token plain"> </span><span class="token keyword" style="color:#c5a5c5">async</span><span class="token plain"> </span><span class="token punctuation" style="color:#657b83">(</span><span class="token parameter">taskData</span><span class="token punctuation" style="color:#657b83">)</span><span class="token plain"> </span><span class="token operator" style="color:#fc929e">=></span><span class="token plain"> </span><span class="token punctuation" style="color:#657b83">{</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> </span><span class="token keyword" style="color:#c5a5c5">const</span><span class="token plain"> condition </span><span class="token operator" style="color:#fc929e">=</span><span class="token plain"> </span><span class="token operator" style="color:#fc929e">...</span><span class="token punctuation" style="color:#657b83">;</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> </span><span class="token keyword" style="color:#c5a5c5">if</span><span class="token plain"> </span><span class="token punctuation" style="color:#657b83">(</span><span class="token operator" style="color:#fc929e">!</span><span class="token plain">condition</span><span class="token punctuation" style="color:#657b83">)</span><span class="token plain"> </span><span class="token punctuation" style="color:#657b83">{</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> </span><span class="token keyword" style="color:#c5a5c5">throw</span><span class="token plain"> </span><span class="token keyword" style="color:#c5a5c5">new</span><span class="token plain"> </span><span class="token class-name" style="color:#fac863">HeadlessJsTaskError</span><span class="token punctuation" style="color:#657b83">(</span><span class="token punctuation" style="color:#657b83">)</span><span class="token punctuation" style="color:#657b83">;</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> </span><span class="token punctuation" style="color:#657b83">}</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"></span><span class="token punctuation" style="color:#657b83">}</span><span class="token punctuation" style="color:#657b83">;</span></div></div></div></div></div><p>If you wish all errors to cause a retry attempt, you will need to catch them and throw the above error.</p><h2><a aria-hidden="true" tabindex="-1" class="anchor enhancedAnchor_3pqN" id="caveats"></a>Caveats<a aria-hidden="true" tabindex="-1" class="hash-link" href="#caveats" title="Direct link to heading">#</a></h2><ul><li>The function passed to <code>setTimeout</code> does not always behave as expected. Instead the function is called only when the application is launched again. If you only need to wait, use the retry functionality.</li><li>By default, your app will crash if you try to run a task while the app is in the foreground. This is to prevent developers from shooting themselves in the foot by doing a lot of work in a task and slowing the UI. You can pass a fourth <code>boolean</code> argument to control this behaviour.</li><li>If you start your service from a <code>BroadcastReceiver</code>, make sure to call <code>HeadlessJsTaskService.acquireWakeLockNow()</code> before returning from <code>onReceive()</code>.</li></ul><h2><a aria-hidden="true" tabindex="-1" class="anchor enhancedAnchor_3pqN" id="example-usage"></a>Example Usage<a aria-hidden="true" tabindex="-1" class="hash-link" href="#example-usage" title="Direct link to heading">#</a></h2><p>Service can be started from Java API. First you need to decide when the service should be started and implement your solution accordingly. Here is an example that reacts to network connection change.</p><p>Following lines shows part of Android manifest file for registering broadcast receiver.</p><div class="mdxCodeBlock_xYIz"><div class="codeBlockContent_rlEb"><button tabindex="0" type="button" aria-label="Copy code to clipboard" class="copyButton_kOW4">Copy</button><div class="prism-code language-xml codeBlock_1AP7"><div class="codeBlockLines_1boI" style="color:#FFFFFF;background:#282C34"><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token tag punctuation" style="color:#657b83"><</span><span class="token tag" style="color:#fc929e">receiver</span><span class="token tag" style="color:#fc929e"> </span><span class="token tag attr-name namespace" style="color:#c5a5c5;opacity:0.7">android:</span><span class="token tag attr-name" style="color:#c5a5c5">name</span><span class="token tag attr-value punctuation" style="color:#657b83">=</span><span class="token tag attr-value punctuation" style="color:#657b83">"</span><span class="token tag attr-value" style="color:#8dc891">.NetworkChangeReceiver</span><span class="token tag attr-value punctuation" style="color:#657b83">"</span><span class="token tag" style="color:#fc929e"> </span><span class="token tag punctuation" style="color:#657b83">></span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> </span><span class="token tag punctuation" style="color:#657b83"><</span><span class="token tag" style="color:#fc929e">intent-filter</span><span class="token tag punctuation" style="color:#657b83">></span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> </span><span class="token tag punctuation" style="color:#657b83"><</span><span class="token tag" style="color:#fc929e">action</span><span class="token tag" style="color:#fc929e"> </span><span class="token tag attr-name namespace" style="color:#c5a5c5;opacity:0.7">android:</span><span class="token tag attr-name" style="color:#c5a5c5">name</span><span class="token tag attr-value punctuation" style="color:#657b83">=</span><span class="token tag attr-value punctuation" style="color:#657b83">"</span><span class="token tag attr-value" style="color:#8dc891">android.net.conn.CONNECTIVITY_CHANGE</span><span class="token tag attr-value punctuation" style="color:#657b83">"</span><span class="token tag" style="color:#fc929e"> </span><span class="token tag punctuation" style="color:#657b83">/></span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> </span><span class="token tag punctuation" style="color:#657b83"></</span><span class="token tag" style="color:#fc929e">intent-filter</span><span class="token tag punctuation" style="color:#657b83">></span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"></span><span class="token tag punctuation" style="color:#657b83"></</span><span class="token tag" style="color:#fc929e">receiver</span><span class="token tag punctuation" style="color:#657b83">></span></div></div></div></div></div><p>Broadcast receiver then handles intent that was broadcasted in onReceive function. This is a great place to check whether your app is on foreground or not. If app is not on foreground we can prepare our intent to be started, with no information or additional information bundled using <code>putExtra</code> (keep in mind bundle can handle only parcelable values). In the end service is started and wakelock is acquired.</p><div class="mdxCodeBlock_xYIz"><div class="codeBlockContent_rlEb"><button tabindex="0" type="button" aria-label="Copy code to clipboard" class="copyButton_kOW4">Copy</button><div class="prism-code language-java codeBlock_1AP7"><div class="codeBlockLines_1boI" style="color:#FFFFFF;background:#282C34"><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token keyword" style="color:#c5a5c5">public</span><span class="token plain"> </span><span class="token keyword" style="color:#c5a5c5">class</span><span class="token plain"> </span><span class="token class-name" style="color:#fac863">NetworkChangeReceiver</span><span class="token plain"> </span><span class="token keyword" style="color:#c5a5c5">extends</span><span class="token plain"> </span><span class="token class-name" style="color:#fac863">BroadcastReceiver</span><span class="token plain"> </span><span class="token punctuation" style="color:#657b83">{</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain" style="display:inline-block">
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</span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> </span><span class="token annotation punctuation" style="color:#657b83">@Override</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> </span><span class="token keyword" style="color:#c5a5c5">public</span><span class="token plain"> </span><span class="token keyword" style="color:#c5a5c5">void</span><span class="token plain"> </span><span class="token function" style="color:#79b6f2">onReceive</span><span class="token punctuation" style="color:#657b83">(</span><span class="token keyword" style="color:#c5a5c5">final</span><span class="token plain"> </span><span class="token class-name" style="color:#fac863">Context</span><span class="token plain"> context</span><span class="token punctuation" style="color:#657b83">,</span><span class="token plain"> </span><span class="token keyword" style="color:#c5a5c5">final</span><span class="token plain"> </span><span class="token class-name" style="color:#fac863">Intent</span><span class="token plain"> intent</span><span class="token punctuation" style="color:#657b83">)</span><span class="token plain"> </span><span class="token punctuation" style="color:#657b83">{</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> </span><span class="token comment" style="color:#93a1a1">/**</span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token comment" style="color:#93a1a1"> This part will be called everytime network connection is changed</span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token comment" style="color:#93a1a1"> e.g. Connected -> Not Connected</span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token comment" style="color:#93a1a1"> **/</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> </span><span class="token keyword" style="color:#c5a5c5">if</span><span class="token plain"> </span><span class="token punctuation" style="color:#657b83">(</span><span class="token operator" style="color:#fc929e">!</span><span class="token function" style="color:#79b6f2">isAppOnForeground</span><span class="token punctuation" style="color:#657b83">(</span><span class="token punctuation" style="color:#657b83">(</span><span class="token plain">context</span><span class="token punctuation" style="color:#657b83">)</span><span class="token punctuation" style="color:#657b83">)</span><span class="token punctuation" style="color:#657b83">)</span><span class="token plain"> </span><span class="token punctuation" style="color:#657b83">{</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> </span><span class="token comment" style="color:#93a1a1">/**</span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token comment" style="color:#93a1a1"> We will start our service and send extra info about</span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token comment" style="color:#93a1a1"> network connections</span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token comment" style="color:#93a1a1"> **/</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> </span><span class="token keyword" style="color:#c5a5c5">boolean</span><span class="token plain"> hasInternet </span><span class="token operator" style="color:#fc929e">=</span><span class="token plain"> </span><span class="token function" style="color:#79b6f2">isNetworkAvailable</span><span class="token punctuation" style="color:#657b83">(</span><span class="token plain">context</span><span class="token punctuation" style="color:#657b83">)</span><span class="token punctuation" style="color:#657b83">;</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> </span><span class="token class-name" style="color:#fac863">Intent</span><span class="token plain"> serviceIntent </span><span class="token operator" style="color:#fc929e">=</span><span class="token plain"> </span><span class="token keyword" style="color:#c5a5c5">new</span><span class="token plain"> </span><span class="token class-name" style="color:#fac863">Intent</span><span class="token punctuation" style="color:#657b83">(</span><span class="token plain">context</span><span class="token punctuation" style="color:#657b83">,</span><span class="token plain"> </span><span class="token class-name" style="color:#fac863">MyTaskService</span><span class="token punctuation" style="color:#657b83">.</span><span class="token keyword" style="color:#c5a5c5">class</span><span class="token punctuation" style="color:#657b83">)</span><span class="token punctuation" style="color:#657b83">;</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> serviceIntent</span><span class="token punctuation" style="color:#657b83">.</span><span class="token function" style="color:#79b6f2">putExtra</span><span class="token punctuation" style="color:#657b83">(</span><span class="token string" style="color:#8dc891">"hasInternet"</span><span class="token punctuation" style="color:#657b83">,</span><span class="token plain"> hasInternet</span><span class="token punctuation" style="color:#657b83">)</span><span class="token punctuation" style="color:#657b83">;</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> context</span><span class="token punctuation" style="color:#657b83">.</span><span class="token function" style="color:#79b6f2">startService</span><span class="token punctuation" style="color:#657b83">(</span><span class="token plain">serviceIntent</span><span class="token punctuation" style="color:#657b83">)</span><span class="token punctuation" style="color:#657b83">;</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> </span><span class="token class-name" style="color:#fac863">HeadlessJsTaskService</span><span class="token punctuation" style="color:#657b83">.</span><span class="token function" style="color:#79b6f2">acquireWakeLockNow</span><span class="token punctuation" style="color:#657b83">(</span><span class="token plain">context</span><span class="token punctuation" style="color:#657b83">)</span><span class="token punctuation" style="color:#657b83">;</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> </span><span class="token punctuation" style="color:#657b83">}</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> </span><span class="token punctuation" style="color:#657b83">}</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain" style="display:inline-block">
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</span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> </span><span class="token keyword" style="color:#c5a5c5">private</span><span class="token plain"> </span><span class="token keyword" style="color:#c5a5c5">boolean</span><span class="token plain"> </span><span class="token function" style="color:#79b6f2">isAppOnForeground</span><span class="token punctuation" style="color:#657b83">(</span><span class="token class-name" style="color:#fac863">Context</span><span class="token plain"> context</span><span class="token punctuation" style="color:#657b83">)</span><span class="token plain"> </span><span class="token punctuation" style="color:#657b83">{</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> </span><span class="token comment" style="color:#93a1a1">/**</span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token comment" style="color:#93a1a1"> We need to check if app is in foreground otherwise the app will crash.</span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token comment" style="color:#93a1a1"> http://stackoverflow.com/questions/8489993/check-android-application-is-in-foreground-or-not</span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token comment" style="color:#93a1a1"> **/</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> </span><span class="token class-name" style="color:#fac863">ActivityManager</span><span class="token plain"> activityManager </span><span class="token operator" style="color:#fc929e">=</span><span class="token plain"> </span><span class="token punctuation" style="color:#657b83">(</span><span class="token class-name" style="color:#fac863">ActivityManager</span><span class="token punctuation" style="color:#657b83">)</span><span class="token plain"> context</span><span class="token punctuation" style="color:#657b83">.</span><span class="token function" style="color:#79b6f2">getSystemService</span><span class="token punctuation" style="color:#657b83">(</span><span class="token class-name" style="color:#fac863">Context</span><span class="token punctuation" style="color:#657b83">.</span><span class="token plain">ACTIVITY_SERVICE</span><span class="token punctuation" style="color:#657b83">)</span><span class="token punctuation" style="color:#657b83">;</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> </span><span class="token class-name" style="color:#fac863">List</span><span class="token generics punctuation" style="color:#657b83"><</span><span class="token generics class-name" style="color:#fac863">ActivityManager</span><span class="token generics punctuation" style="color:#657b83">.</span><span class="token generics class-name" style="color:#fac863">RunningAppProcessInfo</span><span class="token generics punctuation" style="color:#657b83">></span><span class="token plain"> appProcesses </span><span class="token operator" style="color:#fc929e">=</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> activityManager</span><span class="token punctuation" style="color:#657b83">.</span><span class="token function" style="color:#79b6f2">getRunningAppProcesses</span><span class="token punctuation" style="color:#657b83">(</span><span class="token punctuation" style="color:#657b83">)</span><span class="token punctuation" style="color:#657b83">;</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> </span><span class="token keyword" style="color:#c5a5c5">if</span><span class="token plain"> </span><span class="token punctuation" style="color:#657b83">(</span><span class="token plain">appProcesses </span><span class="token operator" style="color:#fc929e">==</span><span class="token plain"> </span><span class="token keyword" style="color:#c5a5c5">null</span><span class="token punctuation" style="color:#657b83">)</span><span class="token plain"> </span><span class="token punctuation" style="color:#657b83">{</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> </span><span class="token keyword" style="color:#c5a5c5">return</span><span class="token plain"> </span><span class="token boolean" style="color:#ff8b50">false</span><span class="token punctuation" style="color:#657b83">;</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> </span><span class="token punctuation" style="color:#657b83">}</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> </span><span class="token keyword" style="color:#c5a5c5">final</span><span class="token plain"> </span><span class="token class-name" style="color:#fac863">String</span><span class="token plain"> packageName </span><span class="token operator" style="color:#fc929e">=</span><span class="token plain"> context</span><span class="token punctuation" style="color:#657b83">.</span><span class="token function" style="color:#79b6f2">getPackageName</span><span class="token punctuation" style="color:#657b83">(</span><span class="token punctuation" style="color:#657b83">)</span><span class="token punctuation" style="color:#657b83">;</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> </span><span class="token keyword" style="color:#c5a5c5">for</span><span class="token plain"> </span><span class="token punctuation" style="color:#657b83">(</span><span class="token class-name" style="color:#fac863">ActivityManager</span><span class="token punctuation" style="color:#657b83">.</span><span class="token class-name" style="color:#fac863">RunningAppProcessInfo</span><span class="token plain"> appProcess </span><span class="token operator" style="color:#fc929e">:</span><span class="token plain"> appProcesses</span><span class="token punctuation" style="color:#657b83">)</span><span class="token plain"> </span><span class="token punctuation" style="color:#657b83">{</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> </span><span class="token keyword" style="color:#c5a5c5">if</span><span class="token plain"> </span><span class="token punctuation" style="color:#657b83">(</span><span class="token plain">appProcess</span><span class="token punctuation" style="color:#657b83">.</span><span class="token plain">importance </span><span class="token operator" style="color:#fc929e">==</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> </span><span class="token class-name" style="color:#fac863">ActivityManager</span><span class="token punctuation" style="color:#657b83">.</span><span class="token class-name" style="color:#fac863">RunningAppProcessInfo</span><span class="token punctuation" style="color:#657b83">.</span><span class="token plain">IMPORTANCE_FOREGROUND </span><span class="token operator" style="color:#fc929e">&&</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> appProcess</span><span class="token punctuation" style="color:#657b83">.</span><span class="token plain">processName</span><span class="token punctuation" style="color:#657b83">.</span><span class="token function" style="color:#79b6f2">equals</span><span class="token punctuation" style="color:#657b83">(</span><span class="token plain">packageName</span><span class="token punctuation" style="color:#657b83">)</span><span class="token punctuation" style="color:#657b83">)</span><span class="token plain"> </span><span class="token punctuation" style="color:#657b83">{</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> </span><span class="token keyword" style="color:#c5a5c5">return</span><span class="token plain"> </span><span class="token boolean" style="color:#ff8b50">true</span><span class="token punctuation" style="color:#657b83">;</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> </span><span class="token punctuation" style="color:#657b83">}</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> </span><span class="token punctuation" style="color:#657b83">}</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> </span><span class="token keyword" style="color:#c5a5c5">return</span><span class="token plain"> </span><span class="token boolean" style="color:#ff8b50">false</span><span class="token punctuation" style="color:#657b83">;</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> </span><span class="token punctuation" style="color:#657b83">}</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain" style="display:inline-block">
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</span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> </span><span class="token keyword" style="color:#c5a5c5">public</span><span class="token plain"> </span><span class="token keyword" style="color:#c5a5c5">static</span><span class="token plain"> </span><span class="token keyword" style="color:#c5a5c5">boolean</span><span class="token plain"> </span><span class="token function" style="color:#79b6f2">isNetworkAvailable</span><span class="token punctuation" style="color:#657b83">(</span><span class="token class-name" style="color:#fac863">Context</span><span class="token plain"> context</span><span class="token punctuation" style="color:#657b83">)</span><span class="token plain"> </span><span class="token punctuation" style="color:#657b83">{</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> </span><span class="token class-name" style="color:#fac863">ConnectivityManager</span><span class="token plain"> cm </span><span class="token operator" style="color:#fc929e">=</span><span class="token plain"> </span><span class="token punctuation" style="color:#657b83">(</span><span class="token class-name" style="color:#fac863">ConnectivityManager</span><span class="token punctuation" style="color:#657b83">)</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> context</span><span class="token punctuation" style="color:#657b83">.</span><span class="token function" style="color:#79b6f2">getSystemService</span><span class="token punctuation" style="color:#657b83">(</span><span class="token class-name" style="color:#fac863">Context</span><span class="token punctuation" style="color:#657b83">.</span><span class="token plain">CONNECTIVITY_SERVICE</span><span class="token punctuation" style="color:#657b83">)</span><span class="token punctuation" style="color:#657b83">;</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> </span><span class="token class-name" style="color:#fac863">NetworkInfo</span><span class="token plain"> netInfo </span><span class="token operator" style="color:#fc929e">=</span><span class="token plain"> cm</span><span class="token punctuation" style="color:#657b83">.</span><span class="token function" style="color:#79b6f2">getActiveNetworkInfo</span><span class="token punctuation" style="color:#657b83">(</span><span class="token punctuation" style="color:#657b83">)</span><span class="token punctuation" style="color:#657b83">;</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> </span><span class="token keyword" style="color:#c5a5c5">return</span><span class="token plain"> </span><span class="token punctuation" style="color:#657b83">(</span><span class="token plain">netInfo </span><span class="token operator" style="color:#fc929e">!=</span><span class="token plain"> </span><span class="token keyword" style="color:#c5a5c5">null</span><span class="token plain"> </span><span class="token operator" style="color:#fc929e">&&</span><span class="token plain"> netInfo</span><span class="token punctuation" style="color:#657b83">.</span><span class="token function" style="color:#79b6f2">isConnected</span><span class="token punctuation" style="color:#657b83">(</span><span class="token punctuation" style="color:#657b83">)</span><span class="token punctuation" style="color:#657b83">)</span><span class="token punctuation" style="color:#657b83">;</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"> </span><span class="token punctuation" style="color:#657b83">}</span><span class="token plain"></span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain" style="display:inline-block">
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</span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain" style="display:inline-block">
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</span></div><div class="token-line" style="color:#FFFFFF;background:#282C34"><span class="token plain"></span><span class="token punctuation" style="color:#657b83">}</span></div></div></div></div></div></div></article><div class="docMetadata margin-vert--xl"><div class="row"><div class="col"><a href="https://github.com/facebook/react-native-website/blob/master/website/../docs/headless-js-android.md" target="_blank" rel="noreferrer noopener"><svg fill="currentColor" height="1.2em" width="1.2em" preserveAspectRatio="xMidYMid meet" viewBox="0 0 40 40" style="margin-right:0.3em;vertical-align:sub"><g><path d="m34.5 11.7l-3 3.1-6.3-6.3 3.1-3q0.5-0.5 1.2-0.5t1.1 0.5l3.9 3.9q0.5 0.4 0.5 1.1t-0.5 1.2z m-29.5 17.1l18.4-18.5 6.3 6.3-18.4 18.4h-6.3v-6.2z"></path></g></svg>Edit this page</a></div><div class="col text--right"><em><small class="docMetadata-updated">Last updated on <time datetime="2020-11-24T10:18:13.000Z" 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