MaterialApp class Null safety

An application that uses Material Design.

A convenience widget that wraps a number of widgets that are commonly required for Material Design applications. It builds upon a WidgetsApp by adding material-design specific functionality, such as AnimatedTheme and GridPaper.

MaterialApp configures its WidgetsApp.textStyle with an ugly red/yellow text style that's intended to warn the developer that their app hasn't defined a default text style. Typically the app's Scaffold builds a Material widget whose default Material.textStyle defines the text style for the entire scaffold.

The MaterialApp configures the top-level Navigator to search for routes in the following order:

For the / route, the home property, if non-null, is used.
Otherwise, the routes table is used, if it has an entry for the route.
Otherwise, onGenerateRoute is called, if provided. It should return a non-null value for any valid route not handled by home and routes.
Finally if all else fails onUnknownRoute is called.

If a Navigator is created, at least one of these options must handle the / route, since it is used when an invalid initialRoute is specified on startup (e.g. by another application launching this one with an intent on Android; see dart:ui.PlatformDispatcher.defaultRouteName).

This widget also configures the observer of the top-level Navigator (if any) to perform Hero animations.

The MaterialApp automatically creates a DefaultSelectionStyle. It uses the colors in the ThemeData.textSelectionTheme if they are not null; otherwise, the MaterialApp sets DefaultSelectionStyle.selectionColor to ColorScheme.primary with 0.4 opacity and DefaultSelectionStyle.cursorColor to ColorScheme.primary.

If home, routes, onGenerateRoute, and onUnknownRoute are all null, and builder is not null, then no Navigator is created.

This example shows how to create a MaterialApp that disables the "debug" banner with a home route that will be displayed when the app is launched.

The MaterialApp displays a Scaffold

MaterialApp(
  home: Scaffold(
    appBar: AppBar(
      title: const Text('Home'),
    ),
  ),
  debugShowCheckedModeBanner: false,
)

This example shows how to create a MaterialApp that uses the routes Map to define the "home" route and an "about" route.

MaterialApp(
  routes: <String, WidgetBuilder>{
    '/': (BuildContext context) {
      return Scaffold(
        appBar: AppBar(
          title: const Text('Home Route'),
        ),
      );
    },
    '/about': (BuildContext context) {
      return Scaffold(
        appBar: AppBar(
          title: const Text('About Route'),
        ),
      );
     }
   },
)

This example shows how to create a MaterialApp that defines a theme that will be used for material widgets in the app.

The MaterialApp displays a Scaffold with a dark background and a blue / grey AppBar at the top

MaterialApp(
  theme: ThemeData(
    brightness: Brightness.dark,
    primaryColor: Colors.blueGrey
  ),
  home: Scaffold(
    appBar: AppBar(
      title: const Text('MaterialApp Theme'),
    ),
  ),
)

Troubleshooting

Why is my app's text red with yellow underlines?

Text widgets that lack a Material ancestor will be rendered with an ugly red/yellow text style.

The typical fix is to give the widget a Scaffold ancestor. The Scaffold creates a Material widget that defines its default text style.

MaterialApp(
  title: 'Material App',
  home: Scaffold(
    body: Center(
      child: Text('Hello World'),
    ),
  ),
)

Constructors

MaterialApp({Key? key, GlobalKey<NavigatorState>? navigatorKey, GlobalKey<ScaffoldMessengerState>? scaffoldMessengerKey, Widget? home, Map<String, WidgetBuilder> routes = const <String, WidgetBuilder>{}, String? initialRoute, RouteFactory? onGenerateRoute, InitialRouteListFactory? onGenerateInitialRoutes, RouteFactory? onUnknownRoute, List<NavigatorObserver> navigatorObservers = const <NavigatorObserver>[], TransitionBuilder? builder, String title = '', GenerateAppTitle? onGenerateTitle, Color? color, ThemeData? theme, ThemeData? darkTheme, ThemeData? highContrastTheme, ThemeData? highContrastDarkTheme, ThemeMode? themeMode = ThemeMode.system, Duration themeAnimationDuration = kThemeAnimationDuration, Curve themeAnimationCurve = Curves.linear, Locale? locale, Iterable<LocalizationsDelegate>? localizationsDelegates, LocaleListResolutionCallback? localeListResolutionCallback, LocaleResolutionCallback? localeResolutionCallback, Iterable<Locale> supportedLocales = const <Locale>[Locale('en', 'US')], bool debugShowMaterialGrid = false, bool showPerformanceOverlay = false, bool checkerboardRasterCacheImages = false, bool checkerboardOffscreenLayers = false, bool showSemanticsDebugger = false, bool debugShowCheckedModeBanner = true, Map<ShortcutActivator, Intent>? shortcuts, Map<Type, Action<Intent>>? actions, String? restorationScopeId, ScrollBehavior? scrollBehavior, bool useInheritedMediaQuery = false}): Creates a MaterialApp.
const
MaterialApp.router({Key? key, GlobalKey<ScaffoldMessengerState>? scaffoldMessengerKey, RouteInformationProvider? routeInformationProvider, RouteInformationParser<Object>? routeInformationParser, RouterDelegate<Object>? routerDelegate, RouterConfig<Object>? routerConfig, BackButtonDispatcher? backButtonDispatcher, TransitionBuilder? builder, String title = '', GenerateAppTitle? onGenerateTitle, Color? color, ThemeData? theme, ThemeData? darkTheme, ThemeData? highContrastTheme, ThemeData? highContrastDarkTheme, ThemeMode? themeMode = ThemeMode.system, Duration themeAnimationDuration = kThemeAnimationDuration, Curve themeAnimationCurve = Curves.linear, Locale? locale, Iterable<LocalizationsDelegate>? localizationsDelegates, LocaleListResolutionCallback? localeListResolutionCallback, LocaleResolutionCallback? localeResolutionCallback, Iterable<Locale> supportedLocales = const <Locale>[Locale('en', 'US')], bool debugShowMaterialGrid = false, bool showPerformanceOverlay = false, bool checkerboardRasterCacheImages = false, bool checkerboardOffscreenLayers = false, bool showSemanticsDebugger = false, bool debugShowCheckedModeBanner = true, Map<ShortcutActivator, Intent>? shortcuts, Map<Type, Action<Intent>>? actions, String? restorationScopeId, ScrollBehavior? scrollBehavior, bool useInheritedMediaQuery = false}): Creates a MaterialApp that uses the Router instead of a Navigator.
const

Properties

actions → Map<Type, Action<Intent>>?: The default map of intent keys to actions for the application.
final
backButtonDispatcher → BackButtonDispatcher?: A delegate that decide whether to handle the Android back button intent.
final
builder → TransitionBuilder?: A builder for inserting widgets above the Navigator or - when the WidgetsApp.router constructor is used - above the Router but below the other widgets created by the WidgetsApp widget, or for replacing the Navigator/Router entirely.
final
checkerboardOffscreenLayers → bool: Turns on checkerboarding of layers rendered to offscreen bitmaps.
final
checkerboardRasterCacheImages → bool: Turns on checkerboarding of raster cache images.
final
color → Color?: The primary color to use for the application in the operating system interface.
final
darkTheme → ThemeData?: The ThemeData to use when a 'dark mode' is requested by the system.
final
debugShowCheckedModeBanner → bool: Turns on a little "DEBUG" banner in debug mode to indicate that the app is in debug mode. This is on by default (in debug mode), to turn it off, set the constructor argument to false. In release mode this has no effect.
final
debugShowMaterialGrid → bool: Turns on a GridPaper overlay that paints a baseline grid Material apps.
final
hashCode → int: The hash code for this object.
nonVirtual">@nonVirtualread-onlyinherited
highContrastDarkTheme → ThemeData?: The ThemeData to use when a 'dark mode' and 'high contrast' is requested by the system.
final
highContrastTheme → ThemeData?: The ThemeData to use when 'high contrast' is requested by the system.
final
home → Widget?: The widget for the default route of the app (Navigator.defaultRouteName, which is /).
final
initialRoute → String?: The name of the first route to show, if a Navigator is built.
final
key → Key?: Controls how one widget replaces another widget in the tree.
finalinherited
locale → Locale?: The initial locale for this app's Localizations widget is based on this value.
final
localeListResolutionCallback → LocaleListResolutionCallback?: This callback is responsible for choosing the app's locale when the app is started, and when the user changes the device's locale.
final
localeResolutionCallback → LocaleResolutionCallback?: The signature of WidgetsApp.localeResolutionCallback.
final
localizationsDelegates → Iterable<LocalizationsDelegate>?: The delegates for this app's Localizations widget.
final
navigatorKey → GlobalKey<NavigatorState>?: A key to use when building the Navigator.
final
navigatorObservers → List<NavigatorObserver>?: The list of observers for the Navigator created for this app.
final
onGenerateInitialRoutes → InitialRouteListFactory?: The routes generator callback used for generating initial routes if initialRoute is provided.
final
onGenerateRoute → RouteFactory?: The route generator callback used when the app is navigated to a named route.
final
onGenerateTitle → GenerateAppTitle?: If non-null this callback function is called to produce the app's title string, otherwise title is used.
final
onUnknownRoute → RouteFactory?: Called when onGenerateRoute fails to generate a route, except for the initialRoute.
final
restorationScopeId → String?: The identifier to use for state restoration of this app.
final
routeInformationParser → RouteInformationParser<Object>?: A delegate to parse the route information from the routeInformationProvider into a generic data type to be processed by the routerDelegate at a later stage.
final
routeInformationProvider → RouteInformationProvider?: A object that provides route information through the RouteInformationProvider.value and notifies its listener when its value changes.
final
routerConfig → RouterConfig<Object>?: An object to configure the underlying Router.
final
routerDelegate → RouterDelegate<Object>?: A delegate that configures a widget, typically a Navigator, with parsed result from the routeInformationParser.
final
routes → Map<String, WidgetBuilder>?: The application's top-level routing table.
final
runtimeType → Type: A representation of the runtime type of the object.
read-onlyinherited
scaffoldMessengerKey → GlobalKey<ScaffoldMessengerState>?: A key to use when building the ScaffoldMessenger.
final
scrollBehavior → ScrollBehavior?: The default ScrollBehavior for the application.
final
shortcuts → Map<ShortcutActivator, Intent>?: The default map of keyboard shortcuts to intents for the application.
final
showPerformanceOverlay → bool: Turns on a performance overlay.
final
showSemanticsDebugger → bool: Turns on an overlay that shows the accessibility information reported by the framework.
final
supportedLocales → Iterable<Locale>: The list of locales that this app has been localized for.
final
theme → ThemeData?: Default visual properties, like colors fonts and shapes, for this app's material widgets.
final
themeAnimationCurve → Curve: The curve to apply when animating theme changes.
final
themeAnimationDuration → Duration: The duration of animated theme changes.
final
themeMode → ThemeMode?: Determines which theme will be used by the application if both theme and darkTheme are provided.
final
title → String: A one-line description used by the device to identify the app for the user.
final
useInheritedMediaQuery → bool: If true, an inherited MediaQuery will be used. If one is not available, or this is false, one will be built from the window.
final

Methods

createElement() → StatefulElement: Creates a StatefulElement to manage this widget's location in the tree.
inherited
createState() → State<MaterialApp>: Creates the mutable state for this widget at a given location in the tree.
override
debugDescribeChildren() → List<DiagnosticsNode>: Returns a list of DiagnosticsNode objects describing this node's children.
protected">@protectedinherited
debugFillProperties(DiagnosticPropertiesBuilder properties) → void: Add additional properties associated with the node.
inherited
noSuchMethod(Invocation invocation) → dynamic: Invoked when a non-existent method or property is accessed.
inherited
toDiagnosticsNode({String? name, DiagnosticsTreeStyle? style}) → DiagnosticsNode: Returns a debug representation of the object that is used by debugging tools and by DiagnosticsNode.toStringDeep.
inherited
toString({DiagnosticLevel minLevel = DiagnosticLevel.info}) → String: A string representation of this object.
inherited
toStringDeep({String prefixLineOne = '', String? prefixOtherLines, DiagnosticLevel minLevel = DiagnosticLevel.debug}) → String: Returns a string representation of this node and its descendants.
inherited
toStringShallow({String joiner = ', ', DiagnosticLevel minLevel = DiagnosticLevel.debug}) → String: Returns a one-line detailed description of the object.
inherited
toStringShort() → String: A short, textual description of this widget.
inherited

Operators

operator ==(Object other) → bool: The equality operator.
nonVirtual">@nonVirtualinherited

Static Methods

createMaterialHeroController() → HeroController: The HeroController used for Material page transitions.