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href="https://firebase.google.com/codelabs/build-leaderboards-with-firestore#0" target="_blank" rel="noopener"><div><span>Build leaderboards with Firestore</span><span class="material-symbols" aria-hidden="true">open_in_new</span></div></a></li><li class="nav-item"><a class="nav-link" href="/cookbook/plugins/google-mobile-ads"><div><span>Add advertising</span></div></a></li><li class="nav-item"><a class="nav-link" href="/cookbook/games/firestore-multiplayer"><div><span>Add multiplayer support</span></div></a></li><li class="nav-item"><a class="nav-link" href="https://codelabs.developers.google.com/codelabs/flutter-in-app-purchases" target="_blank" rel="noopener"><div><span>Add in-app purchases</span><span class="material-symbols" aria-hidden="true">open_in_new</span></div></a></li><li class="nav-item"><a class="nav-link" href="https://firebase.google.com/codelabs/firebase-auth-in-flutter-apps" target="_blank" rel="noopener"><div><span>Add user authentication</span><span class="material-symbols" aria-hidden="true">open_in_new</span></div></a></li><li class="nav-item"><a class="nav-link" href="https://firebase.google.com/docs/crashlytics/get-started?platform=flutter" target="_blank" rel="noopener"><div><span>Debug using Crashlytics</span><span class="material-symbols" aria-hidden="true">open_in_new</span></div></a></li><li class="nav-item"><a class="nav-link" href="https://codelabs.developers.google.com/codelabs/flutter-flame-brick-breaker" target="_blank" rel="noopener"><div><span>Intro to Flame with Flutter</span><span class="material-symbols" aria-hidden="true">open_in_new</span></div></a></li></ul></li><li class="nav-item"><button class="nav-link collapsible collapsed" data-toggle="collapse" data-target="#sidenav-5-4" role="button" aria-expanded="false" aria-controls="sidenav-5-4"><span>Monetization</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="sidenav-5-4"><li class="nav-item"><button class="nav-link collapsible collapsed" data-toggle="collapse" data-target="#sidenav-5-4-1" role="button" aria-expanded="false" aria-controls="sidenav-5-4-1"><span>Advertising</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="sidenav-5-4-1"><li class="nav-item"><a class="nav-link" href="/resources/ads-overview"><div><span>Ads overview</span></div></a></li><li class="nav-item"><a class="nav-link" href="/cookbook/plugins/google-mobile-ads"><div><span>Add advertising</span></div></a></li><li class="nav-item"><a class="nav-link" href="https://codelabs.developers.google.com/codelabs/admob-ads-in-flutter" target="_blank" rel="noopener"><div><span>Add AdMob ads to your Flutter app</span><span class="material-symbols" aria-hidden="true">open_in_new</span></div></a></li><li class="nav-item"><a class="nav-link" href="https://codelabs.developers.google.com/codelabs/admob-inline-ads-in-flutter" target="_blank" rel="noopener"><div><span>Add an AdMob banner and native inline ads</span><span class="material-symbols" aria-hidden="true">open_in_new</span></div></a></li><li class="nav-item"><a class="nav-link" href="https://developers.google.com/admob/flutter/mediation" target="_blank" rel="noopener"><div><span>Google AdMob mediation</span><span class="material-symbols" aria-hidden="true">open_in_new</span></div></a></li><li class="nav-item"><a class="nav-link" href="https://pub.dev/packages/interactive_media_ads" target="_blank" rel="noopener"><div><span>Interactive Media Ads SDK</span><span class="material-symbols" aria-hidden="true">open_in_new</span></div></a></li></ul></li><li class="nav-item"><button class="nav-link collapsible collapsed" data-toggle="collapse" data-target="#sidenav-5-4-2" role="button" aria-expanded="false" aria-controls="sidenav-5-4-2"><span>In-app purchases</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="sidenav-5-4-2"><li class="nav-item"><a class="nav-link" href="/resources/in-app-purchases-overview"><div><span>In-app purchases overview</span></div></a></li><li class="nav-item"><a class="nav-link" href="https://codelabs.developers.google.com/codelabs/flutter-in-app-purchases" target="_blank" rel="noopener"><div><span>Add in-app purchases</span><span class="material-symbols" aria-hidden="true">open_in_new</span></div></a></li></ul></li><li class="nav-item"><button class="nav-link collapsible collapsed" data-toggle="collapse" data-target="#sidenav-5-4-3" role="button" aria-expanded="false" aria-controls="sidenav-5-4-3"><span>Payments</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="sidenav-5-4-3"><li class="nav-item"><a class="nav-link" href="/resources/payments-overview"><div><span>Payments overview</span></div></a></li><li class="nav-item"><a class="nav-link" href="https://pub.dev/packages/pay" target="_blank" rel="noopener"><div><span>Google pay package</span><span class="material-symbols" aria-hidden="true">open_in_new</span></div></a></li></ul></li></ul></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>Maps</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="https://codelabs.developers.google.com/codelabs/google-maps-in-flutter" target="_blank" rel="noopener"><div><span>Add Google maps to a Flutter app</span><span class="material-symbols" aria-hidden="true">open_in_new</span></div></a></li><li class="nav-item"><a class="nav-link" href="https://developers.google.com/maps/flutter-package" target="_blank" rel="noopener"><div><span>Google Maps package</span><span class="material-symbols" aria-hidden="true">open_in_new</span></div></a></li></ul></li><li class="nav-item"><button class="nav-link collapsible collapsed" data-toggle="collapse" data-target="#sidenav-5-6" role="button" aria-expanded="false" aria-controls="sidenav-5-6"><span>News</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="sidenav-5-6"><li class="nav-item"><a class="nav-link" href="/resources/news-toolkit"><div><span>Build a news app</span></div></a></li></ul></li></ul></li><li aria-hidden="true"><div class="sidenav-divider"></div></li><li class="nav-header">User interface</li><li class="nav-item"><a class="nav-link" href="/ui"><div><span>Introduction</span></div></a></li><li class="nav-item"><a class="nav-link" href="/ui/widgets"><div><span>Widget catalog</span></div></a></li><li class="nav-item"><button class="nav-link collapsed collapsible" data-toggle="collapse" data-target="#sidenav-10" role="button" aria-expanded="false" aria-controls="sidenav-10"><span>Layout</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="sidenav-10"><li class="nav-item"><a class="nav-link" href="/ui/layout"><div><span>Introduction</span></div></a></li><li class="nav-item"><a class="nav-link" href="/ui/layout/tutorial"><div><span>Build a layout</span></div></a></li><li class="nav-item"><button class="nav-link collapsible collapsed" data-toggle="collapse" data-target="#sidenav-10-3" role="button" aria-expanded="false" aria-controls="sidenav-10-3"><span>Lists & grids</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="sidenav-10-3"><li class="nav-item"><a class="nav-link" href="/cookbook/lists/basic-list"><div><span>Create and use lists</span></div></a></li><li class="nav-item"><a class="nav-link" href="/cookbook/lists/horizontal-list"><div><span>Create a horizontal list</span></div></a></li><li class="nav-item"><a class="nav-link" href="/cookbook/lists/grid-lists"><div><span>Create a grid view</span></div></a></li><li class="nav-item"><a class="nav-link" href="/cookbook/lists/mixed-list"><div><span>Create lists with different types of items</span></div></a></li><li class="nav-item"><a class="nav-link" href="/cookbook/lists/spaced-items"><div><span>Create lists with spaced items</span></div></a></li><li class="nav-item"><a class="nav-link" href="/cookbook/lists/long-lists"><div><span>Work with long lists</span></div></a></li></ul></li><li class="nav-item"><button class="nav-link collapsible collapsed" data-toggle="collapse" data-target="#sidenav-10-4" role="button" aria-expanded="false" aria-controls="sidenav-10-4"><span>Scrolling</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="sidenav-10-4"><li class="nav-item"><a class="nav-link" href="/ui/layout/scrolling"><div><span>Overview</span></div></a></li><li class="nav-item"><a class="nav-link" href="/ui/layout/scrolling/slivers"><div><span>Use slivers to achieve fancy scrolling</span></div></a></li><li class="nav-item"><a class="nav-link" href="/cookbook/lists/floating-app-bar"><div><span>Place a floating app bar above a list</span></div></a></li><li class="nav-item"><a class="nav-link" href="/cookbook/effects/parallax-scrolling"><div><span>Create a scrolling parallax effect</span></div></a></li></ul></li></ul></li><li class="nav-item"><button class="nav-link collapsed collapsible" data-toggle="collapse" data-target="#sidenav-11" role="button" aria-expanded="false" aria-controls="sidenav-11"><span>Adaptive & responsive design</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="sidenav-11"><li class="nav-item"><a class="nav-link" href="/ui/adaptive-responsive"><div><span>Overview</span></div></a></li><li class="nav-item"><a class="nav-link" href="/ui/adaptive-responsive/general"><div><span>General approach</span></div></a></li><li class="nav-item"><a class="nav-link" href="/ui/adaptive-responsive/safearea-mediaquery"><div><span>SafeArea & MediaQuery</span></div></a></li><li class="nav-item"><a class="nav-link" href="/ui/adaptive-responsive/large-screens"><div><span>Large screens & foldables</span></div></a></li><li class="nav-item"><a class="nav-link" href="/ui/adaptive-responsive/input"><div><span>User input & accessibility</span></div></a></li><li class="nav-item"><a class="nav-link" href="/ui/adaptive-responsive/capabilities"><div><span>Capabilities & policies</span></div></a></li><li class="nav-item"><a class="nav-link" href="/ui/adaptive-responsive/platform-adaptations"><div><span>Automatic platform adaptations</span></div></a></li><li class="nav-item"><a class="nav-link" href="/ui/adaptive-responsive/best-practices"><div><span>Best practices</span></div></a></li><li class="nav-item"><a class="nav-link" href="/ui/adaptive-responsive/more-info"><div><span>Additional resources</span></div></a></li></ul></li><li class="nav-item"><button class="nav-link collapsed collapsible" data-toggle="collapse" data-target="#sidenav-12" role="button" aria-expanded="false" aria-controls="sidenav-12"><span>Design & theming</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="sidenav-12"><li class="nav-item"><a class="nav-link" href="/cookbook/design/themes"><div><span>Share styles with themes</span></div></a></li><li class="nav-item"><a class="nav-link" href="/ui/design/material"><div><span>Material design</span></div></a></li><li class="nav-item"><a class="nav-link" href="/release/breaking-changes/material-3-migration"><div><span>Migrate to Material 3</span></div></a></li><li class="nav-item"><button class="nav-link collapsible collapsed" data-toggle="collapse" data-target="#sidenav-12-4" role="button" aria-expanded="false" aria-controls="sidenav-12-4"><span>Text</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="sidenav-12-4"><li class="nav-item"><a class="nav-link" href="/ui/design/text/typography"><div><span>Fonts & typography</span></div></a></li><li class="nav-item"><a class="nav-link" href="/cookbook/design/fonts"><div><span>Use a custom font</span></div></a></li><li class="nav-item"><a class="nav-link" href="/cookbook/design/package-fonts"><div><span>Export fonts from a package</span></div></a></li><li class="nav-item"><a class="nav-link" href="https://pub.dev/packages/google_fonts" target="_blank" rel="noopener"><div><span>Google Fonts package</span><span class="material-symbols" aria-hidden="true">open_in_new</span></div></a></li></ul></li><li class="nav-item"><button class="nav-link collapsible collapsed" data-toggle="collapse" data-target="#sidenav-12-5" role="button" aria-expanded="false" aria-controls="sidenav-12-5"><span>Custom graphics</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="sidenav-12-5"><li class="nav-item"><a class="nav-link" href="/ui/design/graphics/fragment-shaders"><div><span>Use custom fragment shaders</span></div></a></li></ul></li></ul></li><li class="nav-item"><button class="nav-link collapsed collapsible" data-toggle="collapse" data-target="#sidenav-13" role="button" aria-expanded="false" aria-controls="sidenav-13"><span>Interactivity</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="sidenav-13"><li class="nav-item"><a class="nav-link" href="/ui/interactivity"><div><span>Add interactivity to your app</span></div></a></li><li class="nav-item"><button class="nav-link collapsible collapsed" data-toggle="collapse" data-target="#sidenav-13-2" role="button" aria-expanded="false" aria-controls="sidenav-13-2"><span>Gestures</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="sidenav-13-2"><li class="nav-item"><a class="nav-link" href="/ui/interactivity/gestures"><div><span>Introduction</span></div></a></li><li class="nav-item"><a class="nav-link" href="/cookbook/gestures/handling-taps"><div><span>Handle taps</span></div></a></li><li class="nav-item"><a class="nav-link" href="/ui/interactivity/gestures/drag-outside"><div><span>Drag an object outside an app</span></div></a></li><li class="nav-item"><a class="nav-link" href="/cookbook/effects/drag-a-widget"><div><span>Drag a UI element within an app</span></div></a></li><li class="nav-item"><a class="nav-link" href="/cookbook/gestures/ripples"><div><span>Add Material touch ripples</span></div></a></li><li class="nav-item"><a class="nav-link" href="/cookbook/gestures/dismissible"><div><span>Implement swipe to dismiss</span></div></a></li></ul></li><li class="nav-item"><button class="nav-link collapsible collapsed" data-toggle="collapse" data-target="#sidenav-13-3" role="button" aria-expanded="false" aria-controls="sidenav-13-3"><span>Input & forms</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="sidenav-13-3"><li class="nav-item"><a class="nav-link" href="/cookbook/forms/text-input"><div><span>Create and style a text field</span></div></a></li><li class="nav-item"><a class="nav-link" href="/cookbook/forms/retrieve-input"><div><span>Retrieve the value of a text field</span></div></a></li><li class="nav-item"><a class="nav-link" href="/cookbook/forms/text-field-changes"><div><span>Handle changes to a text field</span></div></a></li><li class="nav-item"><a class="nav-link" href="/cookbook/forms/focus"><div><span>Manage focus in text fields</span></div></a></li><li class="nav-item"><a class="nav-link" href="/cookbook/forms/validation"><div><span>Build a form with validation</span></div></a></li></ul></li><li class="nav-item"><a class="nav-link" href="/cookbook/design/snackbars"><div><span>Display a snackbar</span></div></a></li><li class="nav-item"><a class="nav-link" href="/ui/interactivity/actions-and-shortcuts"><div><span>Implement actions & shortcuts</span></div></a></li><li class="nav-item"><a class="nav-link" href="/ui/interactivity/focus"><div><span>Manage keyboard focus</span></div></a></li></ul></li><li class="nav-item"><button class="nav-link collapsed collapsible" data-toggle="collapse" data-target="#sidenav-14" role="button" aria-expanded="false" aria-controls="sidenav-14"><span>Assets & media</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="sidenav-14"><li class="nav-item"><a class="nav-link" href="/ui/assets/assets-and-images"><div><span>Add assets and images</span></div></a></li><li class="nav-item"><a class="nav-link" href="/cookbook/images/network-image"><div><span>Display images from the internet</span></div></a></li><li class="nav-item"><a class="nav-link" href="/cookbook/images/fading-in-images"><div><span>Fade in images with a placeholder</span></div></a></li><li class="nav-item"><a class="nav-link" href="/cookbook/plugins/play-video"><div><span>Play and pause a video</span></div></a></li><li class="nav-item"><a class="nav-link" href="/ui/assets/asset-transformation"><div><span>Transform assets at build time</span></div></a></li></ul></li><li class="nav-item"><button class="nav-link collapsed collapsible" data-toggle="collapse" data-target="#sidenav-15" role="button" aria-expanded="false" aria-controls="sidenav-15"><span>Navigation & routing</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="sidenav-15"><li class="nav-item"><a class="nav-link" href="/ui/navigation"><div><span>Overview</span></div></a></li><li class="nav-item"><a class="nav-link" href="/cookbook/design/tabs"><div><span>Add tabs to your app</span></div></a></li><li class="nav-item"><a class="nav-link" href="/cookbook/navigation/navigation-basics"><div><span>Navigate to a new screen and back</span></div></a></li><li class="nav-item"><a class="nav-link" href="/cookbook/navigation/passing-data"><div><span>Send data to a new screen</span></div></a></li><li class="nav-item"><a class="nav-link" href="/cookbook/navigation/returning-data"><div><span>Return data from a screen</span></div></a></li><li class="nav-item"><a class="nav-link" href="/cookbook/design/drawer"><div><span>Add a drawer to a screen</span></div></a></li><li class="nav-item"><a class="nav-link" href="/ui/navigation/deep-linking"><div><span>Set up deep linking</span></div></a></li><li class="nav-item"><a class="nav-link" href="/cookbook/navigation/set-up-app-links"><div><span>Set up app links for Android</span></div></a></li><li class="nav-item"><a class="nav-link" href="/cookbook/navigation/set-up-universal-links"><div><span>Set up universal links for iOS</span></div></a></li><li class="nav-item"><a class="nav-link" href="/ui/navigation/url-strategies"><div><span>Configure web URL strategies</span></div></a></li></ul></li><li class="nav-item"><button class="nav-link collapsed collapsible" data-toggle="collapse" data-target="#sidenav-16" role="button" aria-expanded="false" aria-controls="sidenav-16"><span>Animations & transitions</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="sidenav-16"><li class="nav-item"><a class="nav-link" href="/ui/animations"><div><span>Introduction</span></div></a></li><li class="nav-item"><a class="nav-link" href="/ui/animations/tutorial"><div><span>Tutorial</span></div></a></li><li class="nav-item"><a class="nav-link" href="/ui/animations/implicit-animations"><div><span>Implicit animations</span></div></a></li><li class="nav-item"><a class="nav-link" href="/cookbook/animation/animated-container"><div><span>Animate the properties of a container</span></div></a></li><li class="nav-item"><a class="nav-link" href="/cookbook/animation/opacity-animation"><div><span>Fade a widget in and out</span></div></a></li><li class="nav-item"><a class="nav-link" href="/ui/animations/hero-animations"><div><span>Hero animations</span></div></a></li><li class="nav-item"><a class="nav-link" href="/cookbook/animation/page-route-animation"><div><span>Animate a page route transition</span></div></a></li><li class="nav-item"><a class="nav-link" href="/cookbook/animation/physics-simulation"><div><span>Animate using a physics simulation</span></div></a></li><li class="nav-item"><a class="nav-link" href="/ui/animations/staggered-animations"><div><span>Staggered animations</span></div></a></li><li class="nav-item"><a class="nav-link" href="/cookbook/effects/staggered-menu-animation"><div><span>Create a staggered menu animation</span></div></a></li><li class="nav-item"><a class="nav-link" href="/ui/animations/overview"><div><span>API overview</span></div></a></li></ul></li><li class="nav-item"><button class="nav-link collapsed collapsible" data-toggle="collapse" data-target="#sidenav-17" role="button" aria-expanded="false" aria-controls="sidenav-17"><span>Accessibility & internationalization</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="sidenav-17"><li class="nav-item"><a class="nav-link" href="/ui/accessibility-and-internationalization/accessibility"><div><span>Accessibility</span></div></a></li><li class="nav-item"><a class="nav-link" href="/ui/accessibility-and-internationalization/internationalization"><div><span>Internationalization</span></div></a></li></ul></li><li aria-hidden="true"><div class="sidenav-divider"></div></li><li class="nav-header">Beyond UI</li><li class="nav-item"><button class="nav-link active collapsible" data-toggle="collapse" data-target="#sidenav-20" role="button" aria-expanded="true" aria-controls="sidenav-20"><span>Data & backend</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse show" id="sidenav-20"><li class="nav-item"><button class="nav-link collapsible collapsed" data-toggle="collapse" data-target="#sidenav-20-1" role="button" aria-expanded="false" aria-controls="sidenav-20-1"><span>State management</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="sidenav-20-1"><li class="nav-item"><a class="nav-link" href="/data-and-backend/state-mgmt/intro"><div><span>Introduction</span></div></a></li><li class="nav-item"><a class="nav-link" href="/data-and-backend/state-mgmt/declarative"><div><span>Think declaratively</span></div></a></li><li class="nav-item"><a class="nav-link" href="/data-and-backend/state-mgmt/ephemeral-vs-app"><div><span>Ephemeral vs app state</span></div></a></li><li class="nav-item"><a class="nav-link" href="/data-and-backend/state-mgmt/simple"><div><span>Simple app state management</span></div></a></li><li class="nav-item"><a class="nav-link" href="/data-and-backend/state-mgmt/options"><div><span>Options</span></div></a></li></ul></li><li class="nav-item"><button class="nav-link collapsible collapsed" data-toggle="collapse" data-target="#sidenav-20-2" role="button" aria-expanded="false" aria-controls="sidenav-20-2"><span>Networking & http</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="sidenav-20-2"><li class="nav-item"><a class="nav-link" href="/data-and-backend/networking"><div><span>Overview</span></div></a></li><li class="nav-item"><a class="nav-link" href="/cookbook/networking/fetch-data"><div><span>Fetch data from the internet</span></div></a></li><li class="nav-item"><a class="nav-link" href="/cookbook/networking/authenticated-requests"><div><span>Make authenticated requests</span></div></a></li><li class="nav-item"><a class="nav-link" href="/cookbook/networking/send-data"><div><span>Send data to the internet</span></div></a></li><li class="nav-item"><a class="nav-link" href="/cookbook/networking/update-data"><div><span>Update data over the internet</span></div></a></li><li class="nav-item"><a class="nav-link" href="/cookbook/networking/delete-data"><div><span>Delete data on the internet</span></div></a></li><li class="nav-item"><a class="nav-link" href="/cookbook/networking/web-sockets"><div><span>Communicate with WebSockets</span></div></a></li></ul></li><li class="nav-item"><button class="nav-link collapsible collapsed" data-toggle="collapse" data-target="#sidenav-20-3" role="button" aria-expanded="false" aria-controls="sidenav-20-3"><span>Serialization</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="sidenav-20-3"><li class="nav-item"><a class="nav-link" href="/data-and-backend/serialization/json"><div><span>JSON serialization</span></div></a></li><li class="nav-item"><a class="nav-link" href="/cookbook/networking/background-parsing"><div><span>Parse JSON in the background</span></div></a></li></ul></li><li class="nav-item"><button class="nav-link active collapsible" data-toggle="collapse" data-target="#sidenav-20-4" role="button" aria-expanded="true" aria-controls="sidenav-20-4"><span>Persistence</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse show" id="sidenav-20-4"><li class="nav-item"><a class="nav-link" href="/cookbook/persistence/key-value"><div><span>Store key-value data on disk</span></div></a></li><li class="nav-item"><a class="nav-link active" href="/cookbook/persistence/reading-writing-files"><div><span>Read and write files</span></div></a></li><li class="nav-item"><a class="nav-link" href="/cookbook/persistence/sqlite"><div><span>Persist data with SQLite</span></div></a></li></ul></li><li class="nav-item"><button class="nav-link collapsible collapsed" data-toggle="collapse" data-target="#sidenav-20-5" role="button" aria-expanded="false" aria-controls="sidenav-20-5"><span>Firebase</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="sidenav-20-5"><li class="nav-item"><a class="nav-link" href="/data-and-backend/firebase"><div><span>Overview</span></div></a></li><li class="nav-item"><a class="nav-link" href="https://firebase.google.com/docs/flutter/setup" target="_blank" rel="noopener"><div><span>Add Firebase to your Flutter app</span><span class="material-symbols" aria-hidden="true">open_in_new</span></div></a></li></ul></li><li class="nav-item"><a class="nav-link" href="/data-and-backend/google-apis"><div><span>Google APIs</span></div></a></li></ul></li><li class="nav-item"><button class="nav-link collapsed collapsible" data-toggle="collapse" data-target="#sidenav-21" role="button" aria-expanded="false" aria-controls="sidenav-21"><span>App architecture</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="sidenav-21"><li class="nav-item"><a class="nav-link" href="/app-architecture"><div><span>Introduction</span></div></a></li><li class="nav-item"><a class="nav-link" href="/app-architecture/concepts"><div><span>Architecture concepts</span></div></a></li><li class="nav-item"><a class="nav-link" href="/app-architecture/guide"><div><span>Guide to app architecture</span></div></a></li><li class="nav-item"><button class="nav-link collapsible collapsed" data-toggle="collapse" data-target="#sidenav-21-4" role="button" aria-expanded="false" aria-controls="sidenav-21-4"><span>Architecture case study</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="sidenav-21-4"><li class="nav-item"><a class="nav-link" href="/app-architecture/case-study"><div><span>Overview</span></div></a></li><li class="nav-item"><a class="nav-link" href="/app-architecture/case-study/ui-layer"><div><span>UI layer</span></div></a></li><li class="nav-item"><a class="nav-link" href="/app-architecture/case-study/data-layer"><div><span>Data layer</span></div></a></li><li class="nav-item"><a class="nav-link" href="/app-architecture/case-study/dependency-injection"><div><span>Dependency injection</span></div></a></li><li class="nav-item"><a class="nav-link" href="/app-architecture/case-study/testing"><div><span>Testing each layer</span></div></a></li></ul></li><li class="nav-item"><a class="nav-link" href="/app-architecture/recommendations"><div><span>Recommendations</span></div></a></li><li class="nav-item"><a class="nav-link" href="/app-architecture/design-patterns"><div><span>Design patterns</span></div></a></li></ul></li><li class="nav-item"><button class="nav-link collapsed collapsible" data-toggle="collapse" data-target="#sidenav-22" role="button" aria-expanded="false" aria-controls="sidenav-22"><span>Platform integration</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="sidenav-22"><li class="nav-item"><a class="nav-link" href="/reference/supported-platforms"><div><span>Supported platforms</span></div></a></li><li class="nav-item"><a class="nav-link" href="/platform-integration/desktop"><div><span>Build desktop apps with Flutter</span></div></a></li><li class="nav-item"><a class="nav-link" href="/platform-integration/platform-channels"><div><span>Write platform-specific code</span></div></a></li><li class="nav-item"><button class="nav-link collapsible collapsed" data-toggle="collapse" data-target="#sidenav-22-4" role="button" aria-expanded="false" aria-controls="sidenav-22-4"><span>Android</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="sidenav-22-4"><li class="nav-item"><a class="nav-link" href="/platform-integration/android/install-android"><div><span>Add Android as build target</span></div></a></li><li class="nav-item"><a class="nav-link" href="/platform-integration/android/splash-screen"><div><span>Add a splash screen</span></div></a></li><li class="nav-item"><a class="nav-link" href="/platform-integration/android/predictive-back"><div><span>Add predictive back</span></div></a></li><li class="nav-item"><a class="nav-link" href="/platform-integration/android/c-interop"><div><span>Bind to native code</span></div></a></li><li class="nav-item"><a class="nav-link" href="/platform-integration/android/platform-views"><div><span>Host a native Android view</span></div></a></li><li class="nav-item"><a class="nav-link" href="/platform-integration/android/call-jetpack-apis"><div><span>Calling JetPack APIs</span></div></a></li><li class="nav-item"><a class="nav-link" href="/platform-integration/android/compose-activity"><div><span>Launch a Jetpack Compose activity</span></div></a></li><li class="nav-item"><a class="nav-link" href="/platform-integration/android/restore-state-android"><div><span>Restore state on Android</span></div></a></li><li class="nav-item"><a class="nav-link" href="/platform-integration/android/chromeos"><div><span>Target ChromeOS with Android</span></div></a></li></ul></li><li class="nav-item"><button class="nav-link collapsible collapsed" data-toggle="collapse" data-target="#sidenav-22-5" role="button" aria-expanded="false" aria-controls="sidenav-22-5"><span>iOS</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="sidenav-22-5"><li class="nav-item"><a class="nav-link" href="/platform-integration/ios/install-ios"><div><span>Add iOS as build target</span></div></a></li><li class="nav-item"><a class="nav-link" href="/platform-integration/ios/ios-latest"><div><span>Flutter on latest iOS</span></div></a></li><li class="nav-item"><a class="nav-link" href="/platform-integration/ios/apple-frameworks"><div><span>Leverage Apple's system libraries</span></div></a></li><li class="nav-item"><a class="nav-link" href="/platform-integration/ios/launch-screen"><div><span>Add a launch screen</span></div></a></li><li class="nav-item"><a class="nav-link" href="/platform-integration/ios/ios-app-clip"><div><span>Add iOS App Clip support</span></div></a></li><li class="nav-item"><a class="nav-link" href="/platform-integration/ios/app-extensions"><div><span>Add iOS app extensions</span></div></a></li><li class="nav-item"><a class="nav-link" href="/platform-integration/ios/c-interop"><div><span>Bind to native code</span></div></a></li><li class="nav-item"><a class="nav-link" href="/platform-integration/ios/platform-views"><div><span>Host a native iOS view</span></div></a></li><li class="nav-item"><a class="nav-link" href="/platform-integration/ios/ios-debugging"><div><span>Enable debugging on iOS</span></div></a></li><li class="nav-item"><a class="nav-link" href="/platform-integration/ios/restore-state-ios"><div><span>Restore state on iOS</span></div></a></li></ul></li><li class="nav-item"><button class="nav-link collapsible collapsed" data-toggle="collapse" data-target="#sidenav-22-6" role="button" aria-expanded="false" aria-controls="sidenav-22-6"><span>Linux</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="sidenav-22-6"><li class="nav-item"><a class="nav-link" href="/platform-integration/linux/install-linux"><div><span>Add Linux as build target</span></div></a></li><li class="nav-item"><a class="nav-link" href="/platform-integration/linux/building"><div><span>Build a Linux app</span></div></a></li></ul></li><li class="nav-item"><button class="nav-link collapsible collapsed" data-toggle="collapse" data-target="#sidenav-22-7" role="button" aria-expanded="false" aria-controls="sidenav-22-7"><span>macOS</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="sidenav-22-7"><li class="nav-item"><a class="nav-link" href="/platform-integration/macos/install-macos"><div><span>Add macOS as build target</span></div></a></li><li class="nav-item"><a class="nav-link" href="/platform-integration/macos/building"><div><span>Build a macOS app</span></div></a></li><li class="nav-item"><a class="nav-link" href="/platform-integration/macos/c-interop"><div><span>Bind to native code</span></div></a></li><li class="nav-item"><a class="nav-link" href="/platform-integration/macos/platform-views"><div><span>Host a native macOS view</span></div></a></li></ul></li><li class="nav-item"><button class="nav-link collapsible collapsed" data-toggle="collapse" data-target="#sidenav-22-8" role="button" aria-expanded="false" aria-controls="sidenav-22-8"><span>Web</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="sidenav-22-8"><li class="nav-item"><a class="nav-link" href="/platform-integration/web"><div><span>Web support in Flutter</span></div></a></li><li class="nav-item"><a class="nav-link" href="/platform-integration/web/install-web"><div><span>Add web as build target</span></div></a></li><li class="nav-item"><a class="nav-link" href="/platform-integration/web/building"><div><span>Build a web app</span></div></a></li><li class="nav-item"><a class="nav-link" href="/platform-integration/web/wasm"><div><span>Compile to WebAssembly</span></div></a></li><li class="nav-item"><a class="nav-link" href="/platform-integration/web/initialization"><div><span>Customize app initialization</span></div></a></li><li class="nav-item"><a class="nav-link" href="/platform-integration/web/embedding-flutter-web"><div><span>Add Flutter to any web app</span></div></a></li><li class="nav-item"><a class="nav-link" href="/platform-integration/web/web-content-in-flutter"><div><span>Web content in Flutter</span></div></a></li><li class="nav-item"><a class="nav-link" href="/platform-integration/web/renderers"><div><span>Web renderers</span></div></a></li><li class="nav-item"><a class="nav-link" href="/platform-integration/web/web-images"><div><span>Display images on the web</span></div></a></li><li class="nav-item"><a class="nav-link" href="/platform-integration/web/faq"><div><span>Web FAQ</span></div></a></li></ul></li><li class="nav-item"><button class="nav-link collapsible collapsed" data-toggle="collapse" data-target="#sidenav-22-9" role="button" aria-expanded="false" aria-controls="sidenav-22-9"><span>Windows</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="sidenav-22-9"><li class="nav-item"><a class="nav-link" href="/platform-integration/windows/install-windows"><div><span>Add Windows as build target</span></div></a></li><li class="nav-item"><a class="nav-link" href="/platform-integration/windows/building"><div><span>Build a Windows app</span></div></a></li></ul></li></ul></li><li class="nav-item"><button class="nav-link collapsed collapsible" data-toggle="collapse" data-target="#sidenav-23" role="button" aria-expanded="false" aria-controls="sidenav-23"><span>Packages & plugins</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="sidenav-23"><li class="nav-item"><a class="nav-link" href="/packages-and-plugins/using-packages"><div><span>Use packages & plugins</span></div></a></li><li class="nav-item"><a class="nav-link" href="/packages-and-plugins/developing-packages"><div><span>Develop packages & plugins</span></div></a></li><li class="nav-item"><button class="nav-link collapsible collapsed" data-toggle="collapse" data-target="#sidenav-23-3" role="button" aria-expanded="false" aria-controls="sidenav-23-3"><span>Swift Package Manager</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="sidenav-23-3"><li class="nav-item"><a class="nav-link" href="/packages-and-plugins/swift-package-manager/for-app-developers"><div><span>For app developers</span></div></a></li><li class="nav-item"><a class="nav-link" href="/packages-and-plugins/swift-package-manager/for-plugin-authors"><div><span>For plugin authors</span></div></a></li></ul></li><div class="sidenav-divider"></div><li class="nav-item"><a class="nav-link" href="/packages-and-plugins/favorites"><div><span>Flutter Favorites</span></div></a></li><li class="nav-item"><a class="nav-link" href="https://pub.dev/flutter" target="_blank" rel="noopener"><div><span>Package repository</span><span class="material-symbols" aria-hidden="true">open_in_new</span></div></a></li></ul></li><li class="nav-item"><button class="nav-link collapsed collapsible" data-toggle="collapse" data-target="#sidenav-24" role="button" aria-expanded="false" aria-controls="sidenav-24"><span>Testing & debugging</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="sidenav-24"><li class="nav-header">Testing</li><li class="nav-item"><a class="nav-link" href="/testing/overview"><div><span>Overview</span></div></a></li><li class="nav-item"><button class="nav-link collapsible collapsed" data-toggle="collapse" data-target="#sidenav-24-3" role="button" aria-expanded="false" aria-controls="sidenav-24-3"><span>Unit testing</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="sidenav-24-3"><li class="nav-item"><a class="nav-link" href="/cookbook/testing/unit/introduction"><div><span>Introduction</span></div></a></li><li class="nav-item"><a class="nav-link" href="/cookbook/testing/unit/mocking"><div><span>Mock dependencies</span></div></a></li></ul></li><li class="nav-item"><button class="nav-link collapsible collapsed" data-toggle="collapse" data-target="#sidenav-24-4" role="button" aria-expanded="false" aria-controls="sidenav-24-4"><span>Widget testing</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="sidenav-24-4"><li class="nav-item"><a class="nav-link" href="/cookbook/testing/widget/introduction"><div><span>Introduction</span></div></a></li><li class="nav-item"><a class="nav-link" href="/cookbook/testing/widget/finders"><div><span>Find widgets</span></div></a></li><li class="nav-item"><a class="nav-link" href="/cookbook/testing/widget/scrolling"><div><span>Simulate scrolling</span></div></a></li><li class="nav-item"><a class="nav-link" href="/cookbook/testing/widget/tap-drag"><div><span>Simulate user interaction</span></div></a></li></ul></li><li class="nav-item"><button class="nav-link collapsible collapsed" data-toggle="collapse" data-target="#sidenav-24-5" role="button" aria-expanded="false" aria-controls="sidenav-24-5"><span>Integration testing</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="sidenav-24-5"><li class="nav-item"><a class="nav-link" href="/cookbook/testing/integration/introduction"><div><span>Introduction</span></div></a></li><li class="nav-item"><a class="nav-link" href="/testing/integration-tests"><div><span>Write and run an integration test</span></div></a></li><li class="nav-item"><a class="nav-link" href="/cookbook/testing/integration/profiling"><div><span>Profile an integration test</span></div></a></li></ul></li><li class="nav-item"><a class="nav-link" href="/testing/testing-plugins"><div><span>Test a plugin</span></div></a></li><li class="nav-item"><a class="nav-link" href="/testing/plugins-in-tests"><div><span>Handle plugin code in tests</span></div></a></li><li class="nav-header">Debugging</li><li class="nav-item"><a class="nav-link" href="/testing/debugging"><div><span>Debugging tools</span></div></a></li><li class="nav-item"><a class="nav-link" href="/testing/code-debugging"><div><span>Debug your app programmatically</span></div></a></li><li class="nav-item"><a class="nav-link" href="/testing/native-debugging"><div><span>Use a native language debugger</span></div></a></li><li class="nav-item"><a class="nav-link" href="/testing/common-errors"><div><span>Common Flutter errors</span></div></a></li><li class="nav-item"><a class="nav-link" href="/testing/errors"><div><span>Handle errors</span></div></a></li><li class="nav-item"><a class="nav-link" href="/cookbook/maintenance/error-reporting"><div><span>Report errors to a service</span></div></a></li></ul></li><li class="nav-item"><button class="nav-link collapsed collapsible" data-toggle="collapse" data-target="#sidenav-25" role="button" aria-expanded="false" aria-controls="sidenav-25"><span>Performance & optimization</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="sidenav-25"><li class="nav-item"><a class="nav-link" href="/perf"><div><span>Overview</span></div></a></li><li class="nav-item"><a class="nav-link" href="/perf/impeller"><div><span>Impeller</span></div></a></li><li class="nav-item"><a class="nav-link" href="/perf/best-practices"><div><span>Performance best practices</span></div></a></li><li class="nav-item"><a class="nav-link" href="/perf/app-size"><div><span>App size</span></div></a></li><li class="nav-item"><a class="nav-link" href="/perf/deferred-components"><div><span>Deferred components</span></div></a></li><li class="nav-item"><a class="nav-link" href="/perf/rendering-performance"><div><span>Rendering performance</span></div></a></li><li class="nav-item"><a class="nav-link" href="/perf/ui-performance"><div><span>Performance profiling</span></div></a></li><li class="nav-item"><a class="nav-link" href="/perf/web-performance"><div><span>Performance profiling for web</span></div></a></li><li class="nav-item"><a class="nav-link" href="/perf/metrics"><div><span>Performance metrics</span></div></a></li><li class="nav-item"><a class="nav-link" href="/perf/isolates"><div><span>Concurrency and isolates</span></div></a></li><li class="nav-item"><a class="nav-link" href="/perf/faq"><div><span>Performance FAQ</span></div></a></li><li class="nav-item"><a class="nav-link" href="/perf/appendix"><div><span>Appendix</span></div></a></li></ul></li><li class="nav-item"><button class="nav-link collapsed collapsible" data-toggle="collapse" data-target="#sidenav-26" role="button" aria-expanded="false" aria-controls="sidenav-26"><span>Deployment</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="sidenav-26"><li class="nav-item"><a class="nav-link" href="/deployment/obfuscate"><div><span>Obfuscate Dart code</span></div></a></li><li class="nav-item"><a class="nav-link" href="/deployment/flavors"><div><span>Create app flavors for Android</span></div></a></li><li class="nav-item"><a class="nav-link" href="/deployment/flavors-ios"><div><span>Create app flavors for iOS and macOS</span></div></a></li><li class="nav-item"><a class="nav-link" href="/deployment/android"><div><span>Build and release an Android app</span></div></a></li><li class="nav-item"><a class="nav-link" href="/deployment/ios"><div><span>Build and release an iOS app</span></div></a></li><li class="nav-item"><a class="nav-link" href="/deployment/macos"><div><span>Build and release a macOS app</span></div></a></li><li class="nav-item"><a class="nav-link" href="/deployment/linux"><div><span>Build and release a Linux app</span></div></a></li><li class="nav-item"><a class="nav-link" href="/deployment/windows"><div><span>Build and release a Windows app</span></div></a></li><li class="nav-item"><a class="nav-link" href="/deployment/web"><div><span>Build and release a web app</span></div></a></li><li class="nav-item"><a class="nav-link" href="/deployment/cd"><div><span>Set up continuous deployment</span></div></a></li></ul></li><li class="nav-item"><button class="nav-link collapsed collapsible" data-toggle="collapse" data-target="#sidenav-27" role="button" aria-expanded="false" aria-controls="sidenav-27"><span>Add to an existing app</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="sidenav-27"><li class="nav-item"><a class="nav-link" href="/add-to-app"><div><span>Introduction</span></div></a></li><li class="nav-item"><button class="nav-link collapsible collapsed" data-toggle="collapse" data-target="#sidenav-27-2" role="button" aria-expanded="false" aria-controls="sidenav-27-2"><span>Add to an Android app</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="sidenav-27-2"><li class="nav-item"><a class="nav-link" href="/add-to-app/android/project-setup"><div><span>Set up Android project</span></div></a></li><li class="nav-item"><a class="nav-link" href="/add-to-app/android/add-flutter-screen"><div><span>Add a single Flutter screen</span></div></a></li><li class="nav-item"><a class="nav-link" href="/add-to-app/android/add-flutter-fragment"><div><span>Add a Flutter Fragment</span></div></a></li><li class="nav-item"><a class="nav-link" href="/add-to-app/android/add-flutter-view"><div><span>Add a Flutter View</span></div></a></li><li class="nav-item"><a class="nav-link" href="/add-to-app/android/plugin-setup"><div><span>Use a Flutter plugin</span></div></a></li></ul></li><li class="nav-item"><button class="nav-link collapsible collapsed" data-toggle="collapse" data-target="#sidenav-27-3" role="button" aria-expanded="false" aria-controls="sidenav-27-3"><span>Add to an iOS app</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="sidenav-27-3"><li class="nav-item"><a class="nav-link" href="/add-to-app/ios/project-setup"><div><span>Set up iOS project</span></div></a></li><li class="nav-item"><a class="nav-link" href="/add-to-app/ios/add-flutter-screen"><div><span>Add a single Flutter screen</span></div></a></li></ul></li><li class="nav-item"><a class="nav-link" href="/platform-integration/web/embedding-flutter-web"><div><span>Add to a web app</span></div></a></li><li class="nav-item"><a class="nav-link" href="/add-to-app/debugging"><div><span>Debug embedded Flutter module</span></div></a></li><li class="nav-item"><a class="nav-link" href="/add-to-app/multiple-flutters"><div><span>Add multiple Flutter instances</span></div></a></li><li class="nav-item"><a class="nav-link" href="/add-to-app/performance"><div><span>Loading sequence and performance</span></div></a></li></ul></li><li aria-hidden="true"><div class="sidenav-divider"></div></li><li class="nav-item"><button class="nav-link collapsed collapsible" data-toggle="collapse" data-target="#sidenav-29" role="button" aria-expanded="false" aria-controls="sidenav-29"><span>Tools & editors</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="sidenav-29"><li class="nav-item"><a class="nav-link" href="/tools/android-studio"><div><span>Android Studio & IntelliJ</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/vs-code"><div><span>Visual Studio Code</span></div></a></li><li class="nav-item"><button class="nav-link collapsible collapsed" data-toggle="collapse" data-target="#sidenav-29-3" role="button" aria-expanded="false" aria-controls="sidenav-29-3"><span>DevTools</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="sidenav-29-3"><li class="nav-item"><a class="nav-link" href="/tools/devtools"><div><span>Overview</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/devtools/android-studio"><div><span>Run from Android Studio & IntelliJ</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/devtools/vscode"><div><span>Run from VS Code</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/devtools/cli"><div><span>Run from command line</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/devtools/inspector"><div><span>Flutter inspector</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/devtools/legacy-inspector"><div><span>Legacy Flutter inspector</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/devtools/performance"><div><span>Performance view</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/devtools/cpu-profiler"><div><span>CPU Profiler view</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/devtools/memory"><div><span>Memory view</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/devtools/console"><div><span>Debug console view</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/devtools/network"><div><span>Network view</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/devtools/debugger"><div><span>Debugger</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/devtools/logging"><div><span>Logging view</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/devtools/app-size"><div><span>App size tool</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/devtools/extensions"><div><span>DevTools extensions</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/devtools/deep-links"><div><span>Validate deep links</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/devtools/release-notes"><div><span>Release notes</span></div></a></li></ul></li><li class="nav-item"><a class="nav-link" href="/tools/sdk"><div><span>SDK overview</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/pubspec"><div><span>Flutter's pubspec options</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/flutter-fix"><div><span>Automated fixes</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/formatting"><div><span>Code formatting</span></div></a></li></ul></li><li class="nav-item"><button class="nav-link collapsed collapsible" data-toggle="collapse" data-target="#sidenav-30" role="button" aria-expanded="false" aria-controls="sidenav-30"><span>Flutter concepts</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="sidenav-30"><li class="nav-item"><a class="nav-link" href="/resources/architectural-overview"><div><span>Architectural overview</span></div></a></li><li class="nav-item"><a class="nav-link" href="/resources/inside-flutter"><div><span>Inside Flutter</span></div></a></li><li class="nav-item"><a class="nav-link" href="/ui/layout/constraints"><div><span>Understanding constraints</span></div></a></li><li class="nav-item"><a class="nav-link" href="/testing/build-modes"><div><span>Flutter's build modes</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/hot-reload"><div><span>Hot reload</span></div></a></li></ul></li><li class="nav-item"><button class="nav-link collapsed collapsible" data-toggle="collapse" data-target="#sidenav-31" role="button" aria-expanded="false" aria-controls="sidenav-31"><span>Resources</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="sidenav-31"><li class="nav-item"><a class="nav-link" href="/resources/faq"><div><span>FAQ</span></div></a></li><li class="nav-item"><a class="nav-link" href="/resources/books"><div><span>Books</span></div></a></li><li class="nav-item"><a class="nav-link" href="/resources/videos"><div><span>Videos</span></div></a></li><li class="nav-item"><a class="nav-link" href="/resources/courses"><div><span>Courses</span></div></a></li><li class="nav-item"><a class="nav-link" href="/resources/bootstrap-into-dart"><div><span>Learn Dart</span></div></a></li><li class="nav-item"><a class="nav-link" href="/resources/support"><div><span>Get support</span></div></a></li><div class="sidenav-divider"></div><li class="nav-item"><button class="nav-link collapsible collapsed" data-toggle="collapse" data-target="#sidenav-31-8" role="button" aria-expanded="false" aria-controls="sidenav-31-8"><span>Contribute</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="sidenav-31-8"><li class="nav-item"><a class="nav-link" href="/resources/bug-reports"><div><span>Create useful bug reports</span></div></a></li><li class="nav-item"><a class="nav-link" href="https://github.com/flutter/flutter/blob/main/CONTRIBUTING.md" target="_blank" rel="noopener"><div><span>Contribute to Flutter</span><span class="material-symbols" aria-hidden="true">open_in_new</span></div></a></li><li class="nav-item"><a class="nav-link" href="/resources/design-docs"><div><span>Discover proposed features</span></div></a></li></ul></li><li class="nav-item"><button class="nav-link collapsible collapsed" data-toggle="collapse" data-target="#sidenav-31-9" role="button" aria-expanded="false" aria-controls="sidenav-31-9"><span>Reference</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="sidenav-31-9"><li class="nav-item"><a class="nav-link" href="/dash"><div><span>Who is Dash?</span></div></a></li><li class="nav-item"><a class="nav-link" href="/reference/widgets"><div><span>Widget index</span></div></a></li><li class="nav-item"><a class="nav-link" href="/reference/flutter-cli"><div><span>flutter CLI</span></div></a></li><li class="nav-item"><a class="nav-link" href="https://api.flutter.dev" target="_blank" rel="noopener"><div><span>API docs</span><span class="material-symbols" aria-hidden="true">open_in_new</span></div></a></li></ul></li></ul></li></ul></nav></div><main class="site-content"><div id="site-toc--side" class="site-toc"><header class="site-toc__title">Contents</header><ul class="section-nav"><li class="toc-entry nav-item"><a class="nav-link" href="#1-find-the-correct-local-path">1. Find the correct local path</a></li><li class="toc-entry nav-item"><a class="nav-link" href="#2-create-a-reference-to-the-file-location">2. Create a reference to the file location</a></li><li class="toc-entry nav-item"><a class="nav-link" href="#3-write-data-to-the-file">3. Write data to the file</a></li><li class="toc-entry nav-item"><a class="nav-link" href="#4-read-data-from-the-file">4. Read data from the file</a></li><li class="toc-entry nav-item"><a class="nav-link" href="#complete-example">Complete example</a></li></ul></div><article><header class="site-content__title"><h1 id="document-title">Read and write files</h1><nav class="breadcrumbs" aria-label="breadcrumb"><ol vocab="https://schema.org/" typeof="BreadcrumbList"><li class="breadcrumb-item" property="itemListElement" typeof="ListItem"><a href="/cookbook" property="item" typeof="WebPage"><span property="name">Cookbook</span></a><meta property="position" content="0"><span class="material-symbols child-icon" aria-hidden="true">chevron_right</span></li><li class="breadcrumb-item" property="itemListElement" typeof="ListItem"><a href="/cookbook/persistence" property="item" typeof="WebPage"><span property="name">Persistence</span></a><meta property="position" content="1"><span class="material-symbols child-icon" aria-hidden="true">chevron_right</span></li><li class="breadcrumb-item active" property="itemListElement" typeof="ListItem" aria-current="page"><a href="/cookbook/persistence/reading-writing-files" property="item" typeof="WebPage"><span property="name">Read and write files</span></a><meta property="position" content="2"></li></ol></nav></header><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="#1-find-the-correct-local-path">1. Find the correct local path</a></li><li class="toc-entry"><a href="#2-create-a-reference-to-the-file-location">2. Create a reference to the file location</a></li><li class="toc-entry"><a href="#3-write-data-to-the-file">3. Write data to the file</a></li><li class="toc-entry"><a href="#4-read-data-from-the-file">4. Read data from the file</a></li><li class="toc-entry"><a href="#complete-example">Complete example</a></li></ul></div> <?code-excerpt path-base="cookbook/persistence/reading_writing_files/"?> <p>In some cases, you need to read and write files to disk. For example, you might need to persist data across app launches, or download data from the internet and save it for later offline use.</p><p>To save files to disk on mobile or desktop apps, combine the <a href="https://pub.dev/packages/path_provider"><code>path_provider</code></a> plugin with the <a href="https://api.flutter.dev/flutter/dart-io/dart-io-library.html"><code>dart:io</code></a> library.</p><p>This recipe uses the following steps:</p><ol><li>Find the correct local path.</li><li>Create a reference to the file location.</li><li>Write data to the file.</li><li>Read data from the file.</li></ol><p>To learn more, watch this Package of the Week video on the <code>path_provider</code> package:</p><iframe width="560" height="315" src="https://www.youtube.com/embed/Ci4t-NkOY3I" title="path_provider | Flutter package of the week" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" allowfullscreen loading="lazy"></iframe><br><p><a href="https://www.youtube.com/watch/Ci4t-NkOY3I" target="_blank" rel="noopener" title="Open 'path_provider | Flutter package of the week' video in new tab">path_provider | Flutter package of the week</a></p><aside class="alert alert-info"><div class="alert-header"><i class="material-symbols" aria-hidden="true">info</i> <span>Note</span></div><div class="alert-content"><p>This recipe doesn't work with web apps at this time. To follow the discussion on this issue, check out <code>flutter/flutter</code> <a href="https://github.com/flutter/flutter/issues/45296">issue #45296</a>.</p></div></aside><div class="header-wrapper"><h2 id="1-find-the-correct-local-path">1. Find the correct local path</h2><a class="heading-link" href="#1-find-the-correct-local-path" aria-label="Link to '1. Find the correct local path' section">#</a></div><p>This example displays a counter. When the counter changes, write data on disk so you can read it again when the app loads. Where should you store this data?</p><p>The <a href="https://pub.dev/packages/path_provider"><code>path_provider</code></a> package provides a platform-agnostic way to access commonly used locations on the device's file system. The plugin currently supports access to two file system locations:</p><dl><dt><em>Temporary directory</em></dt><dd>A temporary directory (cache) that the system can clear at any time. On iOS, this corresponds to the <a href="https://developer.apple.com/documentation/foundation/nssearchpathdirectory/nscachesdirectory"><code>NSCachesDirectory</code></a>. On Android, this is the value that <a href="https://developer.android.com/reference/android/content/Context#getCacheDir()"><code>getCacheDir()</code></a> returns.</dd><dt><em>Documents directory</em></dt><dd>A directory for the app to store files that only it can access. The system clears the directory only when the app is deleted. On iOS, this corresponds to the <code>NSDocumentDirectory</code>. On Android, this is the <code>AppData</code> directory.</dd></dl><p>This example stores information in the documents directory. You can find the path to the documents directory as follows:</p> <?code-excerpt "lib/main.dart (localPath)"?> <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:#BD2314">import</span><span style="color:#0C7064"> 'package:path_provider/path_provider.dart'</span><span style="color:#222222">;</span></span> <span class="line"><span style="color:#6E6E70"> // 路路路</span></span> <span class="line"><span style="color:#0468D7"> Future</span><span style="color:#222222"><</span><span style="color:#0468D7">String</span><span style="color:#222222">> </span><span style="color:#BD2314">get</span><span style="color:#222222"> _localPath </span><span style="color:#BD2314">async</span><span style="color:#222222"> {</span></span> <span class="line"><span style="color:#BD2314"> final</span><span style="color:#222222"> directory = </span><span style="color:#BD2314">await</span><span style="color:#6200EE"> getApplicationDocumentsDirectory</span><span style="color:#222222">();</span></span> <span class="line"></span> <span class="line"><span style="color:#BD2314"> return</span><span style="color:#222222"> directory.path;</span></span> <span class="line"><span style="color:#222222"> }</span></span></code></pre></div></div><div class="header-wrapper"><h2 id="2-create-a-reference-to-the-file-location">2. Create a reference to the file location</h2><a class="heading-link" href="#2-create-a-reference-to-the-file-location" aria-label="Link to '2. Create a reference to the file location' section">#</a></div><p>Once you know where to store the file, create a reference to the file's full location. You can use the <a href="https://api.flutter.dev/flutter/dart-io/File-class.html"><code>File</code></a> class from the <a href="https://api.flutter.dev/flutter/dart-io/dart-io-library.html"><code>dart:io</code></a> library to achieve this.</p> <?code-excerpt "lib/main.dart (localFile)"?> <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:#0468D7">Future</span><span style="color:#222222"><</span><span style="color:#0468D7">File</span><span style="color:#222222">> </span><span style="color:#BD2314">get</span><span style="color:#222222"> _localFile </span><span style="color:#BD2314">async</span><span style="color:#222222"> {</span></span> <span class="line"><span style="color:#BD2314"> final</span><span style="color:#222222"> path = </span><span style="color:#BD2314">await</span><span style="color:#222222"> _localPath;</span></span> <span class="line"><span style="color:#BD2314"> return</span><span style="color:#0468D7"> File</span><span style="color:#222222">(</span><span style="color:#0C7064">'</span><span style="color:#0C7064">$</span><span style="color:#222222">path</span><span style="color:#0C7064">/counter.txt'</span><span style="color:#222222">);</span></span> <span class="line"><span style="color:#222222">}</span></span></code></pre></div></div><div class="header-wrapper"><h2 id="3-write-data-to-the-file">3. Write data to the file</h2><a class="heading-link" href="#3-write-data-to-the-file" aria-label="Link to '3. Write data to the file' section">#</a></div><p>Now that you have a <code>File</code> to work with, use it to read and write data. First, write some data to the file. The counter is an integer, but is written to the file as a string using the <code>'$counter'</code> syntax.</p> <?code-excerpt "lib/main.dart (writeCounter)"?> <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:#0468D7">Future</span><span style="color:#222222"><</span><span style="color:#0468D7">File</span><span style="color:#222222">> </span><span style="color:#6200EE">writeCounter</span><span style="color:#222222">(</span><span style="color:#0468D7">int</span><span style="color:#222222"> counter) </span><span style="color:#BD2314">async</span><span style="color:#222222"> {</span></span> <span class="line"><span style="color:#BD2314"> final</span><span style="color:#222222"> file = </span><span style="color:#BD2314">await</span><span style="color:#222222"> _localFile;</span></span> <span class="line"></span> <span class="line"><span style="color:#6E6E70"> // Write the file</span></span> <span class="line"><span style="color:#BD2314"> return</span><span style="color:#222222"> file.</span><span style="color:#6200EE">writeAsString</span><span style="color:#222222">(</span><span style="color:#0C7064">'</span><span style="color:#0C7064">$</span><span style="color:#222222">counter</span><span style="color:#0C7064">'</span><span style="color:#222222">);</span></span> <span class="line"><span style="color:#222222">}</span></span></code></pre></div></div><div class="header-wrapper"><h2 id="4-read-data-from-the-file">4. Read data from the file</h2><a class="heading-link" href="#4-read-data-from-the-file" aria-label="Link to '4. Read data from the file' section">#</a></div><p>Now that you have some data on disk, you can read it. Once again, use the <code>File</code> class.</p> <?code-excerpt "lib/main.dart (readCounter)"?> <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:#0468D7">Future</span><span style="color:#222222"><</span><span style="color:#0468D7">int</span><span style="color:#222222">> </span><span style="color:#6200EE">readCounter</span><span style="color:#222222">() </span><span style="color:#BD2314">async</span><span style="color:#222222"> {</span></span> <span class="line"><span style="color:#BD2314"> try</span><span style="color:#222222"> {</span></span> <span class="line"><span style="color:#BD2314"> final</span><span style="color:#222222"> file = </span><span style="color:#BD2314">await</span><span style="color:#222222"> _localFile;</span></span> <span class="line"></span> <span class="line"><span style="color:#6E6E70"> // Read the file</span></span> <span class="line"><span style="color:#BD2314"> final</span><span style="color:#222222"> contents = </span><span style="color:#BD2314">await</span><span style="color:#222222"> file.</span><span style="color:#6200EE">readAsString</span><span style="color:#222222">();</span></span> <span class="line"></span> <span class="line"><span style="color:#BD2314"> return</span><span style="color:#0468D7"> int</span><span style="color:#222222">.</span><span style="color:#6200EE">parse</span><span style="color:#222222">(contents);</span></span> <span class="line"><span style="color:#222222"> } </span><span style="color:#BD2314">catch</span><span style="color:#222222"> (e) {</span></span> <span class="line"><span style="color:#6E6E70"> // If encountering an error, return 0</span></span> <span class="line"><span style="color:#BD2314"> return</span><span style="color:#0C7064"> 0</span><span style="color:#222222">;</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"><h2 id="complete-example">Complete example</h2><a class="heading-link" href="#complete-example" aria-label="Link to 'Complete example' section">#</a></div> <?code-excerpt "lib/main.dart"?> <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:#BD2314">import</span><span style="color:#0C7064"> 'dart:async'</span><span style="color:#222222">;</span></span> <span class="line"><span style="color:#BD2314">import</span><span style="color:#0C7064"> 'dart:io'</span><span style="color:#222222">;</span></span> <span class="line"></span> <span class="line"><span style="color:#BD2314">import</span><span style="color:#0C7064"> 'package:flutter/material.dart'</span><span style="color:#222222">;</span></span> <span class="line"><span style="color:#BD2314">import</span><span style="color:#0C7064"> 'package:path_provider/path_provider.dart'</span><span style="color:#222222">;</span></span> <span class="line"></span> <span class="line"><span style="color:#BD2314">void</span><span style="color:#6200EE"> main</span><span style="color:#222222">() {</span></span> <span class="line"><span style="color:#6200EE"> runApp</span><span style="color:#222222">(</span></span> <span class="line"><span style="color:#0468D7"> MaterialApp</span><span style="color:#222222">(</span></span> <span class="line"><span style="color:#222222"> title: </span><span style="color:#0C7064">'Reading and Writing Files'</span><span style="color:#222222">,</span></span> <span class="line"><span style="color:#222222"> home: </span><span style="color:#0468D7">FlutterDemo</span><span style="color:#222222">(storage: </span><span style="color:#0468D7">CounterStorage</span><span style="color:#222222">()),</span></span> <span class="line"><span style="color:#222222"> ),</span></span> <span class="line"><span style="color:#222222"> );</span></span> <span class="line"><span style="color:#222222">}</span></span> <span class="line"></span> <span class="line"><span style="color:#BD2314">class</span><span style="color:#0468D7"> CounterStorage</span><span style="color:#222222"> {</span></span> <span class="line"><span style="color:#0468D7"> Future</span><span style="color:#222222"><</span><span style="color:#0468D7">String</span><span style="color:#222222">> </span><span style="color:#BD2314">get</span><span style="color:#222222"> _localPath </span><span style="color:#BD2314">async</span><span style="color:#222222"> {</span></span> <span class="line"><span style="color:#BD2314"> final</span><span style="color:#222222"> directory = </span><span style="color:#BD2314">await</span><span style="color:#6200EE"> getApplicationDocumentsDirectory</span><span style="color:#222222">();</span></span> <span class="line"></span> <span class="line"><span style="color:#BD2314"> return</span><span style="color:#222222"> directory.path;</span></span> <span class="line"><span style="color:#222222"> }</span></span> <span class="line"></span> <span class="line"><span style="color:#0468D7"> Future</span><span style="color:#222222"><</span><span style="color:#0468D7">File</span><span style="color:#222222">> </span><span style="color:#BD2314">get</span><span style="color:#222222"> _localFile </span><span style="color:#BD2314">async</span><span style="color:#222222"> {</span></span> <span class="line"><span style="color:#BD2314"> final</span><span style="color:#222222"> path = </span><span style="color:#BD2314">await</span><span style="color:#222222"> _localPath;</span></span> <span class="line"><span style="color:#BD2314"> return</span><span style="color:#0468D7"> File</span><span style="color:#222222">(</span><span style="color:#0C7064">'</span><span style="color:#0C7064">$</span><span style="color:#222222">path</span><span style="color:#0C7064">/counter.txt'</span><span style="color:#222222">);</span></span> <span class="line"><span style="color:#222222"> }</span></span> <span class="line"></span> <span class="line"><span style="color:#0468D7"> Future</span><span style="color:#222222"><</span><span style="color:#0468D7">int</span><span style="color:#222222">> </span><span style="color:#6200EE">readCounter</span><span style="color:#222222">() </span><span style="color:#BD2314">async</span><span style="color:#222222"> {</span></span> <span class="line"><span style="color:#BD2314"> try</span><span style="color:#222222"> {</span></span> <span class="line"><span style="color:#BD2314"> final</span><span style="color:#222222"> file = </span><span style="color:#BD2314">await</span><span style="color:#222222"> _localFile;</span></span> <span class="line"></span> <span class="line"><span style="color:#6E6E70"> // Read the file</span></span> <span class="line"><span style="color:#BD2314"> final</span><span style="color:#222222"> contents = </span><span style="color:#BD2314">await</span><span style="color:#222222"> file.</span><span style="color:#6200EE">readAsString</span><span style="color:#222222">();</span></span> <span class="line"></span> <span class="line"><span style="color:#BD2314"> return</span><span style="color:#0468D7"> int</span><span style="color:#222222">.</span><span style="color:#6200EE">parse</span><span style="color:#222222">(contents);</span></span> <span class="line"><span style="color:#222222"> } </span><span style="color:#BD2314">catch</span><span style="color:#222222"> (e) {</span></span> <span class="line"><span style="color:#6E6E70"> // If encountering an error, return 0</span></span> <span class="line"><span style="color:#BD2314"> return</span><span style="color:#0C7064"> 0</span><span style="color:#222222">;</span></span> <span class="line"><span style="color:#222222"> }</span></span> <span class="line"><span style="color:#222222"> }</span></span> <span class="line"></span> <span class="line"><span style="color:#0468D7"> Future</span><span style="color:#222222"><</span><span style="color:#0468D7">File</span><span style="color:#222222">> </span><span style="color:#6200EE">writeCounter</span><span style="color:#222222">(</span><span style="color:#0468D7">int</span><span style="color:#222222"> counter) </span><span style="color:#BD2314">async</span><span style="color:#222222"> {</span></span> <span class="line"><span style="color:#BD2314"> final</span><span style="color:#222222"> file = </span><span style="color:#BD2314">await</span><span style="color:#222222"> _localFile;</span></span> <span class="line"></span> <span class="line"><span style="color:#6E6E70"> // Write the file</span></span> <span class="line"><span style="color:#BD2314"> return</span><span style="color:#222222"> file.</span><span style="color:#6200EE">writeAsString</span><span style="color:#222222">(</span><span style="color:#0C7064">'</span><span style="color:#0C7064">$</span><span style="color:#222222">counter</span><span style="color:#0C7064">'</span><span style="color:#222222">);</span></span> <span class="line"><span style="color:#222222"> }</span></span> <span class="line"></span> <span class="line"><span style="color:#222222">}</span></span> <span class="line"></span> <span class="line"><span style="color:#BD2314">class</span><span style="color:#0468D7"> FlutterDemo</span><span style="color:#BD2314"> extends</span><span style="color:#0468D7"> StatefulWidget</span><span style="color:#222222"> {</span></span> <span class="line"><span style="color:#BD2314"> const</span><span style="color:#0468D7"> FlutterDemo</span><span style="color:#222222">({</span><span style="color:#BD2314">super</span><span style="color:#222222">.key, </span><span style="color:#BD2314">required</span><span style="color:#BD2314"> this</span><span style="color:#222222">.storage});</span></span> <span class="line"></span> <span class="line"><span style="color:#BD2314"> final</span><span style="color:#0468D7"> CounterStorage</span><span style="color:#222222"> storage;</span></span> <span class="line"></span> <span class="line"><span style="color:#BD2314"> @override</span></span> <span class="line"><span style="color:#0468D7"> State</span><span style="color:#222222"><</span><span style="color:#0468D7">FlutterDemo</span><span style="color:#222222">> </span><span style="color:#6200EE">createState</span><span style="color:#222222">() => </span><span style="color:#0468D7">_FlutterDemoState</span><span style="color:#222222">();</span></span> <span class="line"><span style="color:#222222">}</span></span> <span class="line"></span> <span class="line"><span style="color:#BD2314">class</span><span style="color:#0468D7"> _FlutterDemoState</span><span style="color:#BD2314"> extends</span><span style="color:#0468D7"> State</span><span style="color:#222222"><</span><span style="color:#0468D7">FlutterDemo</span><span style="color:#222222">> {</span></span> <span class="line"><span style="color:#0468D7"> int</span><span style="color:#222222"> _counter = </span><span style="color:#0C7064">0</span><span style="color:#222222">;</span></span> <span class="line"></span> <span class="line"><span style="color:#BD2314"> @override</span></span> <span class="line"><span style="color:#BD2314"> void</span><span style="color:#6200EE"> initState</span><span style="color:#222222">() {</span></span> <span class="line"><span style="color:#BD2314"> super</span><span style="color:#222222">.</span><span style="color:#6200EE">initState</span><span style="color:#222222">();</span></span> <span class="line"><span style="color:#222222"> widget.storage.</span><span style="color:#6200EE">readCounter</span><span style="color:#222222">().</span><span style="color:#6200EE">then</span><span style="color:#222222">((value) {</span></span> <span class="line"><span style="color:#6200EE"> setState</span><span style="color:#222222">(() {</span></span> <span class="line"><span style="color:#222222"> _counter = value;</span></span> <span class="line"><span style="color:#222222"> });</span></span> <span class="line"><span style="color:#222222"> });</span></span> <span class="line"><span style="color:#222222"> }</span></span> <span class="line"></span> <span class="line"><span style="color:#0468D7"> Future</span><span style="color:#222222"><</span><span style="color:#0468D7">File</span><span style="color:#222222">> </span><span style="color:#6200EE">_incrementCounter</span><span style="color:#222222">() {</span></span> <span class="line"><span style="color:#6200EE"> setState</span><span style="color:#222222">(() {</span></span> <span class="line"><span style="color:#222222"> _counter++;</span></span> <span class="line"><span style="color:#222222"> });</span></span> <span class="line"></span> <span class="line"><span style="color:#6E6E70"> // Write the variable as a string to the file.</span></span> <span class="line"><span style="color:#BD2314"> return</span><span style="color:#222222"> widget.storage.</span><span style="color:#6200EE">writeCounter</span><span style="color:#222222">(_counter);</span></span> <span class="line"><span style="color:#222222"> }</span></span> <span class="line"></span> <span class="line"><span style="color:#BD2314"> @override</span></span> <span class="line"><span style="color:#0468D7"> Widget</span><span style="color:#6200EE"> build</span><span style="color:#222222">(</span><span style="color:#0468D7">BuildContext</span><span style="color:#222222"> context) {</span></span> <span class="line"><span style="color:#BD2314"> return</span><span style="color:#0468D7"> Scaffold</span><span style="color:#222222">(</span></span> <span class="line"><span style="color:#222222"> appBar: </span><span style="color:#0468D7">AppBar</span><span style="color:#222222">(title: </span><span style="color:#BD2314">const</span><span style="color:#0468D7"> Text</span><span style="color:#222222">(</span><span style="color:#0C7064">'Reading and Writing Files'</span><span style="color:#222222">)),</span></span> <span class="line"><span style="color:#222222"> body: </span><span style="color:#0468D7">Center</span><span style="color:#222222">(</span></span> <span class="line"><span style="color:#222222"> child: </span><span style="color:#0468D7">Text</span><span style="color:#222222">(</span><span style="color:#0C7064">'Button tapped </span><span style="color:#0C7064">$</span><span style="color:#222222">_counter</span><span style="color:#0C7064"> time</span><span style="color:#0C7064">${</span><span style="color:#222222">_counter</span><span style="color:#0C7064"> == 1 ? </span><span style="color:#0C7064">''</span><span style="color:#0C7064"> : </span><span style="color:#0C7064">'s'</span><span style="color:#0C7064">}</span><span style="color:#0C7064">.'</span><span style="color:#222222">),</span></span> <span class="line"><span style="color:#222222"> ),</span></span> <span class="line"><span style="color:#222222"> floatingActionButton: </span><span style="color:#0468D7">FloatingActionButton</span><span style="color:#222222">(</span></span> <span class="line"><span style="color:#222222"> onPressed: _incrementCounter,</span></span> <span class="line"><span style="color:#222222"> tooltip: </span><span style="color:#0C7064">'Increment'</span><span style="color:#222222">,</span></span> <span class="line"><span style="color:#222222"> child: </span><span style="color:#BD2314">const</span><span style="color:#0468D7"> Icon</span><span style="color:#222222">(</span><span style="color:#0468D7">Icons</span><span style="color:#222222">.add),</span></span> <span class="line"><span style="color:#222222"> ),</span></span> <span class="line"><span style="color:#222222"> );</span></span> <span class="line"><span style="color:#222222"> }</span></span> <span class="line"><span style="color:#222222">}</span></span></code></pre></div></div><p id="page-github-links"><span>Unless stated otherwise, the documentation on this site reflects the latest stable version of Flutter. Page last updated on 2025-02-12.</span> <a href="https://github.com/flutter/website/tree/main/src/content/cookbook/persistence/reading-writing-files.md" target="_blank" rel="noopener">View source</a> <span>or </span><a href="https://github.com/flutter/website/issues/new?template=1_page_issue.yml&&page-url=https://docs.flutter.dev/cookbook/persistence/reading-writing-files/&page-source=https://github.com/flutter/website/tree/main/src/content/cookbook/persistence/reading-writing-files.md" title="Report an issue with this page" target="_blank" rel="noopener">report an issue</a>.</p></article></main></div><footer id="site-footer"><div class="footer-section footer-main"><a class="brand" href="https://flutter.dev"><img src="/assets/images/branding/flutter/logo+text/horizontal/white.svg" alt="Flutter logo" width="164"></a><div class="footer-social-links"><a class="icon-button" href="https://medium.com/flutter" target="_blank" rel="noopener" title="Flutter's Medium blog"><svg><use href="/assets/images/social/medium.svg#medium"></use></svg> </a><a class="icon-button" href="https://youtube.com/@flutterdev" target="_blank" rel="noopener" title="Flutter's YouTube"><svg><use href="/assets/images/social/youtube.svg#youtube"></use></svg> </a><a class="icon-button" href="https://github.com/flutter" target="_blank" rel="noopener" title="Flutter's GitHub"><svg><use href="/assets/images/social/github.svg#github"></use></svg> </a><a class="icon-button" href="https://bsky.app/profile/flutter.dev" target="_blank" rel="noopener" title="Flutter's Bluesky"><svg><use href="/assets/images/social/bluesky.svg#bluesky"></use></svg> </a><a class="icon-button" href="https://twitter.com/FlutterDev" target="_blank" rel="noopener" title="Flutter's X (Twitter)"><svg><use href="/assets/images/social/x.svg#x"></use></svg></a></div></div><div class="footer-section footer-tray"><div class="footer-licenses">Except as otherwise noted, this site is licensed under a <a href="https://creativecommons.org/licenses/by/4.0/">Creative Commons Attribution 4.0 International License</a>, and code samples are licensed under the <a href="https://opensource.org/licenses/BSD-3-Clause">3-Clause BSD License</a>.</div><div class="footer-utility-links"><ul><li><a href="/tos" title="Terms of use">Terms</a></li><li><a href="/brand" title="Brand usage guidelines">Brand</a></li><li><a href="https://policies.google.com/privacy" target="_blank" rel="noopener" title="Privacy policy">Privacy</a></li><li><a href="/security" title="Security philosophy and practices">Security</a></li></ul></div></div></footer></div><script src="/assets/js/tabs.js?v=4"></script><script src="/assets/js/archive.js?v=4"></script><script src="/assets/js/main.js?v=4"></script></body></html>