Enable library_private_types_in_public_api lint (#81578)

analysis_options.yaml

@@ -122,6 +122,7 @@ linter:
     - leading_newlines_in_multiline_strings
     - library_names
     - library_prefixes
+    - library_private_types_in_public_api
     # - lines_longer_than_80_chars # not required by flutter style
     - list_remove_unrelated_type
     # - literal_only_boolean_expressions # too many false positives: https://github.com/dart-lang/sdk/issues/34181

dev/benchmarks/macrobenchmarks/lib/src/animation_with_microtasks.dart

@@ -8,8 +8,7 @@ class AnimationWithMicrotasks extends StatefulWidget {
   const AnimationWithMicrotasks({Key key}) : super(key: key);
 
   @override
-  _AnimationWithMicrotasksState createState() =>
-      _AnimationWithMicrotasksState();
+  State<AnimationWithMicrotasks> createState() => _AnimationWithMicrotasksState();
 }
 
 class _AnimationWithMicrotasksState extends State<AnimationWithMicrotasks> {

dev/benchmarks/macrobenchmarks/lib/src/backdrop_filter.dart

@@ -10,7 +10,7 @@ class BackdropFilterPage extends StatefulWidget {
   const BackdropFilterPage({Key key}) : super(key: key);
 
   @override
-  _BackdropFilterPageState createState() => _BackdropFilterPageState();
+  State<BackdropFilterPage> createState() => _BackdropFilterPageState();
 }
 
 class _BackdropFilterPageState extends State<BackdropFilterPage> with TickerProviderStateMixin {

dev/benchmarks/macrobenchmarks/lib/src/color_filter_and_fade.dart

@@ -12,7 +12,7 @@ class ColorFilterAndFadePage extends StatefulWidget {
   const ColorFilterAndFadePage({Key key}) : super(key: key);
 
   @override
-  _ColorFilterAndFadePageState createState() => _ColorFilterAndFadePageState();
+  State<ColorFilterAndFadePage> createState() => _ColorFilterAndFadePageState();
 }
 
 class _ColorFilterAndFadePageState extends State<ColorFilterAndFadePage> with TickerProviderStateMixin {

dev/benchmarks/macrobenchmarks/lib/src/filtered_child_animation.dart

@@ -23,7 +23,7 @@ class FilteredChildAnimationPage extends StatefulWidget {
   final bool initialUseRepaintBoundary;
 
   @override
-  _FilteredChildAnimationPageState createState() => _FilteredChildAnimationPageState();
+  State<FilteredChildAnimationPage> createState() => _FilteredChildAnimationPageState();
 }
 
 class _FilteredChildAnimationPageState extends State<FilteredChildAnimationPage> with SingleTickerProviderStateMixin {

dev/benchmarks/macrobenchmarks/lib/src/large_image_changer.dart

@@ -11,7 +11,7 @@ class LargeImageChangerPage extends StatefulWidget {
   const LargeImageChangerPage({Key key}) : super(key: key);
 
   @override
-  _LargeImageChangerState createState() => _LargeImageChangerState();
+  State<LargeImageChangerPage> createState() => _LargeImageChangerState();
 }
 
 class _LargeImageChangerState extends State<LargeImageChangerPage> {

dev/benchmarks/macrobenchmarks/lib/src/multi_widget_construction.dart

@@ -12,8 +12,7 @@ class MultiWidgetConstructTable extends StatefulWidget {
   final int rowCount;
 
   @override
-  _MultiWidgetConstructTableState createState() =>
-      _MultiWidgetConstructTableState();
+  State<MultiWidgetConstructTable> createState() => _MultiWidgetConstructTableState();
 }
 
 class _MultiWidgetConstructTableState extends State<MultiWidgetConstructTable>

dev/benchmarks/macrobenchmarks/lib/src/post_backdrop_filter.dart

@@ -10,7 +10,7 @@ class PostBackdropFilterPage extends StatefulWidget {
   const PostBackdropFilterPage({Key key}) : super(key: key);
 
   @override
-  _PostBackdropFilterPageState createState() => _PostBackdropFilterPageState();
+  State<PostBackdropFilterPage> createState() => _PostBackdropFilterPageState();
 }
 
 class _PostBackdropFilterPageState extends State<PostBackdropFilterPage> with TickerProviderStateMixin {

dev/benchmarks/macrobenchmarks/lib/src/web/bench_mouse_region_grid_hover.dart

@@ -37,12 +37,12 @@ class _NestedMouseRegion extends StatelessWidget {
 /// Measures our ability to hit test mouse regions.
 class BenchMouseRegionGridHover extends WidgetRecorder {
   BenchMouseRegionGridHover() : super(name: benchmarkName) {
-    tester = _Tester(onDataPoint: handleDataPoint);
+    _tester = _Tester(onDataPoint: handleDataPoint);
   }
 
   static const String benchmarkName = 'bench_mouse_region_grid_hover';
 
-  _Tester tester;
+  _Tester _tester;
 
   void handleDataPoint(Duration duration) {
     profile.addDataPoint('hitTestDuration', duration, reported: true);
@@ -67,8 +67,8 @@ class BenchMouseRegionGridHover extends WidgetRecorder {
     if (!started) {
       started = true;
       SchedulerBinding.instance.addPostFrameCallback((Duration timeStamp) async {
-        tester.start();
-        registerDidStop(tester.stop);
+        _tester.start();
+        registerDidStop(_tester.stop);
       });
     }
     super.frameDidDraw();

dev/benchmarks/macrobenchmarks/lib/src/web/bench_mouse_region_grid_scroll.dart

@@ -21,7 +21,7 @@ class BenchMouseRegionGridScroll extends WidgetRecorder {
 
   static const String benchmarkName = 'bench_mouse_region_grid_scroll';
 
-  final _Tester tester = _Tester();
+  final _Tester _tester = _Tester();
 
   // Use a non-trivial border to force Web to switch painter
   Border _getBorder(int columnIndex, int rowIndex) {
@@ -42,8 +42,8 @@ class BenchMouseRegionGridScroll extends WidgetRecorder {
     if (!started) {
       started = true;
       SchedulerBinding.instance.addPostFrameCallback((Duration timeStamp) async {
-        tester.start();
-        registerDidStop(tester.stop);
+        _tester.start();
+        registerDidStop(_tester.stop);
       });
     }
     super.frameDidDraw();

dev/benchmarks/macrobenchmarks/lib/src/web/bench_mouse_region_mixed_grid_hover.dart

@@ -56,12 +56,12 @@ class _NestedListener extends StatelessWidget {
 /// Measures our ability to hit test mouse regions.
 class BenchMouseRegionMixedGridHover extends WidgetRecorder {
   BenchMouseRegionMixedGridHover() : super(name: benchmarkName) {
-    tester = _Tester(onDataPoint: handleDataPoint);
+    _tester = _Tester(onDataPoint: handleDataPoint);
   }
 
   static const String benchmarkName = 'bench_mouse_region_mixed_grid_hover';
 
-  _Tester tester;
+  _Tester _tester;
 
   void handleDataPoint(Duration duration) {
     profile.addDataPoint('hitTestDuration', duration, reported: true);
@@ -86,8 +86,8 @@ class BenchMouseRegionMixedGridHover extends WidgetRecorder {
     if (!started) {
       started = true;
       SchedulerBinding.instance.addPostFrameCallback((Duration timeStamp) async {
-        tester.start();
-        registerDidStop(tester.stop);
+        _tester.start();
+        registerDidStop(_tester.stop);
       });
     }
     super.frameDidDraw();

dev/benchmarks/macrobenchmarks/lib/src/web/bench_text_layout.dart

@@ -203,11 +203,11 @@ enum _TestMode {
 /// colors. Each color's description is made of several [Text] nodes.
 class BenchBuildColorsGrid extends WidgetBuildRecorder {
   BenchBuildColorsGrid.canvas()
-      : mode = _TestMode.useCanvasTextLayout, super(name: canvasBenchmarkName);
+      : _mode = _TestMode.useCanvasTextLayout, super(name: canvasBenchmarkName);
   BenchBuildColorsGrid.dom()
-      : mode = _TestMode.useDomTextLayout, super(name: domBenchmarkName);
+      : _mode = _TestMode.useDomTextLayout, super(name: domBenchmarkName);
   BenchBuildColorsGrid.canvasKit()
-      : mode = _TestMode.useCanvasKit, super(name: canvasKitBenchmarkName);
+      : _mode = _TestMode.useCanvasKit, super(name: canvasKitBenchmarkName);
 
   /// Disables tracing for this benchmark.
   ///
@@ -224,16 +224,16 @@ class BenchBuildColorsGrid extends WidgetBuildRecorder {
   static const String canvasKitBenchmarkName = 'text_canvas_kit_color_grid';
 
   /// Whether to use the new canvas-based text measurement implementation.
-  final _TestMode mode;
+  final _TestMode _mode;
 
   num _textLayoutMicros = 0;
 
   @override
   Future<void> setUpAll() async {
-    if (mode == _TestMode.useCanvasTextLayout) {
+    if (_mode == _TestMode.useCanvasTextLayout) {
       _useCanvasText(true);
     }
-    if (mode == _TestMode.useDomTextLayout) {
+    if (_mode == _TestMode.useDomTextLayout) {
       _useCanvasText(false);
     }
     registerEngineBenchmarkValueListener('text_layout', (num value) {
@@ -258,7 +258,7 @@ class BenchBuildColorsGrid extends WidgetBuildRecorder {
     // We need to do this before calling [super.frameDidDraw] because the latter
     // updates the value of [showWidget] in preparation for the next frame.
     // TODO(yjbanov): https://github.com/flutter/flutter/issues/53877
-    if (showWidget && mode != _TestMode.useCanvasKit) {
+    if (showWidget && _mode != _TestMode.useCanvasKit) {
       profile.addDataPoint(
         'text_layout',
         Duration(microseconds: _textLayoutMicros.toInt()),

dev/benchmarks/macrobenchmarks/lib/src/web/bench_wrapbox_scroll.dart

@@ -34,7 +34,7 @@ class MyHomePage extends StatefulWidget {
   final String title;
 
   @override
-  _MyHomePageState createState() => _MyHomePageState();
+  State<MyHomePage> createState() => _MyHomePageState();
 }
 
 class _MyHomePageState extends State<MyHomePage> {

dev/benchmarks/multiple_flutters/module/lib/main.dart

@@ -34,7 +34,7 @@ class MyHomePage extends StatefulWidget {
   final String? title;
 
   @override
-  _MyHomePageState createState() => _MyHomePageState();
+  State<MyHomePage> createState() => _MyHomePageState();
 }
 
 class _MyHomePageState extends State<MyHomePage> {

dev/benchmarks/platform_views_layout/lib/main.dart

@@ -99,7 +99,7 @@ class RotationContainer extends StatefulWidget {
   const RotationContainer({Key? key}) : super(key: key);
 
   @override
-  _RotationContainerState createState() => _RotationContainerState();
+  State<RotationContainer> createState() => _RotationContainerState();
 }
 
 class _RotationContainerState extends State<RotationContainer>

dev/benchmarks/platform_views_layout_hybrid_composition/lib/main.dart

@@ -104,7 +104,7 @@ class RotationContainer extends StatefulWidget {
   const RotationContainer({Key? key}) : super(key: key);
 
   @override
-  _RotationContainerState createState() => _RotationContainerState();
+  State<RotationContainer> createState() => _RotationContainerState();
 }
 
 class _RotationContainerState extends State<RotationContainer>

dev/bots/test/analyze-sample-code-test-dart-ui/ui.dart

@@ -26,8 +26,8 @@ library dart.ui;
 /// }
 /// ```
 /// {@end-tool}
-const _KeepToString keepToString = _KeepToString();
+const Object keepToString = _KeepToString();
 
 class _KeepToString {
   const _KeepToString();
-}
+}
\ No newline at end of file

dev/devicelab/lib/framework/adb.dart

@@ -64,9 +64,9 @@ abstract class DeviceDiscovery {
       case DeviceOperatingSystem.android:
         return AndroidDeviceDiscovery();
       case DeviceOperatingSystem.androidArm:
-        return AndroidDeviceDiscovery(cpu: _AndroidCPU.arm);
+        return AndroidDeviceDiscovery(cpu: AndroidCPU.arm);
       case DeviceOperatingSystem.androidArm64:
-        return AndroidDeviceDiscovery(cpu: _AndroidCPU.arm64);
+        return AndroidDeviceDiscovery(cpu: AndroidCPU.arm64);
       case DeviceOperatingSystem.ios:
         return IosDeviceDiscovery();
       case DeviceOperatingSystem.fuchsia:
@@ -158,19 +158,19 @@ abstract class Device {
   }
 }
 
-enum _AndroidCPU {
+enum AndroidCPU {
   arm,
   arm64,
 }
 
 class AndroidDeviceDiscovery implements DeviceDiscovery {
-  factory AndroidDeviceDiscovery({_AndroidCPU cpu}) {
+  factory AndroidDeviceDiscovery({AndroidCPU cpu}) {
     return _instance ??= AndroidDeviceDiscovery._(cpu);
   }
 
   AndroidDeviceDiscovery._(this.cpu);
 
-  final _AndroidCPU cpu;
+  final AndroidCPU cpu;
 
   // Parses information about a device. Example:
   //
@@ -199,9 +199,9 @@ class AndroidDeviceDiscovery implements DeviceDiscovery {
     if (cpu == null)
       return true;
     switch (cpu) {
-      case _AndroidCPU.arm64:
+      case AndroidCPU.arm64:
         return device.isArm64();
-      case _AndroidCPU.arm:
+      case AndroidCPU.arm:
         return device.isArm();
     }
     return true;

dev/integration_tests/abstract_method_smoke_test/lib/main.dart

@@ -32,7 +32,7 @@ class HomePage extends StatefulWidget {
   const HomePage({Key? key}) : super(key: key);
 
   @override
-  _HomePage createState() => _HomePage();
+  State<HomePage> createState() => _HomePage();
 }
 
 class _HomePage extends State<HomePage> {

dev/integration_tests/android_views/lib/wm_integrations.dart

@@ -33,7 +33,7 @@ enum _LastTestStatus {
 class WindowManagerBodyState extends State<WindowManagerBody> {
 
   MethodChannel? viewChannel;
-  _LastTestStatus lastTestStatus = _LastTestStatus.pending;
+  _LastTestStatus _lastTestStatus = _LastTestStatus.pending;
   String? lastError;
   int? id;
   int windowClickCount = 0;
@@ -53,7 +53,7 @@ class WindowManagerBodyState extends State<WindowManagerBody> {
               onPlatformViewCreated: onPlatformViewCreated,
             ),
           ),
-          if (lastTestStatus != _LastTestStatus.pending) _statusWidget(),
+          if (_lastTestStatus != _LastTestStatus.pending) _statusWidget(),
           if (viewChannel != null) ... <Widget>[
             ElevatedButton(
               key: const ValueKey<String>('ShowAlertDialog'),
@@ -86,34 +86,34 @@ class WindowManagerBodyState extends State<WindowManagerBody> {
   }
 
   Widget _statusWidget() {
-    assert(lastTestStatus != _LastTestStatus.pending);
-    final String? message = lastTestStatus == _LastTestStatus.success ? 'Success' : lastError;
+    assert(_lastTestStatus != _LastTestStatus.pending);
+    final String? message = _lastTestStatus == _LastTestStatus.success ? 'Success' : lastError;
     return Container(
-      color: lastTestStatus == _LastTestStatus.success ? Colors.green : Colors.red,
+      color: _lastTestStatus == _LastTestStatus.success ? Colors.green : Colors.red,
       child: Text(
         message!,
         key: const ValueKey<String>('Status'),
         style: TextStyle(
-          color: lastTestStatus == _LastTestStatus.error ? Colors.yellow : null,
+          color: _lastTestStatus == _LastTestStatus.error ? Colors.yellow : null,
         ),
       ),
     );
   }
 
   Future<void> onShowAlertDialogPressed() async {
-    if (lastTestStatus != _LastTestStatus.pending) {
+    if (_lastTestStatus != _LastTestStatus.pending) {
       setState(() {
-        lastTestStatus = _LastTestStatus.pending;
+        _lastTestStatus = _LastTestStatus.pending;
       });
     }
     try {
       await viewChannel?.invokeMethod<void>('showAndHideAlertDialog');
       setState(() {
-        lastTestStatus = _LastTestStatus.success;
+        _lastTestStatus = _LastTestStatus.success;
       });
     } catch(e) {
       setState(() {
-        lastTestStatus = _LastTestStatus.error;
+        _lastTestStatus = _LastTestStatus.error;
         lastError = '$e';
       });
     }
@@ -127,7 +127,7 @@ class WindowManagerBodyState extends State<WindowManagerBody> {
       });
     } catch(e) {
       setState(() {
-        lastTestStatus = _LastTestStatus.error;
+        _lastTestStatus = _LastTestStatus.error;
         lastError = '$e';
       });
     }

dev/integration_tests/channels/lib/main.dart

@@ -22,7 +22,7 @@ class TestApp extends StatefulWidget {
   const TestApp({Key key}) : super(key: key);
 
   @override
-  _TestAppState createState() => _TestAppState();
+  State<TestApp> createState() => _TestAppState();
 }
 
 class _TestAppState extends State<TestApp> {

dev/integration_tests/flavors/lib/main.dart

@@ -15,7 +15,7 @@ class Flavor extends StatefulWidget {
   const Flavor({Key? key}) : super(key: key);
 
   @override
-  _FlavorState createState() => _FlavorState();
+  State<Flavor> createState() => _FlavorState();
 }
 
 class _FlavorState extends State<Flavor> {

dev/integration_tests/flutter_gallery/lib/demo/animation/home.dart

@@ -420,7 +420,7 @@ class AnimationDemoHome extends StatefulWidget {
   static const String routeName = '/animation';
 
   @override
-  _AnimationDemoHomeState createState() => _AnimationDemoHomeState();
+  State<AnimationDemoHome> createState() => _AnimationDemoHomeState();
 }
 
 class _AnimationDemoHomeState extends State<AnimationDemoHome> {

dev/integration_tests/flutter_gallery/lib/demo/calculator/home.dart

@@ -10,10 +10,10 @@ class Calculator extends StatefulWidget {
   const Calculator({Key? key}) : super(key: key);
 
   @override
-  _CalculatorState createState() => _CalculatorState();
+  State<Calculator> createState() => CalculatorState();
 }
 
-class _CalculatorState extends State<Calculator> {
+class CalculatorState extends State<Calculator> {
   /// As the user taps keys we update the current `_expression` and we also
   /// keep a stack of previous expressions so we can return to earlier states
   /// when the user hits the DEL key.
@@ -156,7 +156,7 @@ class CalcDisplay extends StatelessWidget {
 class KeyPad extends StatelessWidget {
   const KeyPad({ Key? key, this.calcState }) : super(key: key);
 
-  final _CalculatorState? calcState;
+  final CalculatorState? calcState;
 
   @override
   Widget build(BuildContext context) {
@@ -265,7 +265,7 @@ class CalcKey extends StatelessWidget {
 }
 
 class NumberKey extends CalcKey {
-  NumberKey(int value, _CalculatorState? calcState, {Key? key})
+  NumberKey(int value, CalculatorState? calcState, {Key? key})
     : super('$value', () {
         calcState!.handleNumberTap(value);
       }, key: key);

dev/integration_tests/flutter_gallery/lib/demo/cupertino/cupertino_alert_demo.dart

@@ -12,7 +12,7 @@ class CupertinoAlertDemo extends StatefulWidget {
   static const String routeName = '/cupertino/alert';
 
   @override
-  _CupertinoAlertDemoState createState() => _CupertinoAlertDemoState();
+  State<CupertinoAlertDemo> createState() => _CupertinoAlertDemoState();
 }
 
 class _CupertinoAlertDemoState extends State<CupertinoAlertDemo> {

dev/integration_tests/flutter_gallery/lib/demo/cupertino/cupertino_buttons_demo.dart

@@ -12,7 +12,7 @@ class CupertinoButtonsDemo extends StatefulWidget {
   static const String routeName = '/cupertino/buttons';
 
   @override
-  _CupertinoButtonDemoState createState() => _CupertinoButtonDemoState();
+  State<CupertinoButtonsDemo> createState() => _CupertinoButtonDemoState();
 }
 
 class _CupertinoButtonDemoState extends State<CupertinoButtonsDemo> {

dev/integration_tests/flutter_gallery/lib/demo/cupertino/cupertino_picker_demo.dart

@@ -17,7 +17,7 @@ class CupertinoPickerDemo extends StatefulWidget {
   static const String routeName = '/cupertino/picker';
 
   @override
-  _CupertinoPickerDemoState createState() => _CupertinoPickerDemoState();
+  State<CupertinoPickerDemo> createState() => _CupertinoPickerDemoState();
 }
 
 class _BottomPicker extends StatelessWidget {

dev/integration_tests/flutter_gallery/lib/demo/cupertino/cupertino_refresh_demo.dart

@@ -14,7 +14,7 @@ class CupertinoRefreshControlDemo extends StatefulWidget {
   static const String routeName = '/cupertino/refresh';
 
   @override
-  _CupertinoRefreshControlDemoState createState() => _CupertinoRefreshControlDemoState();
+  State<CupertinoRefreshControlDemo> createState() => _CupertinoRefreshControlDemoState();
 }
 
 class _CupertinoRefreshControlDemoState extends State<CupertinoRefreshControlDemo> {

dev/integration_tests/flutter_gallery/lib/demo/cupertino/cupertino_segmented_control_demo.dart

@@ -17,7 +17,7 @@ class CupertinoSegmentedControlDemo extends StatefulWidget {
   static const String routeName = 'cupertino/segmented_control';
 
   @override
-  _CupertinoSegmentedControlDemoState createState() => _CupertinoSegmentedControlDemoState();
+  State<CupertinoSegmentedControlDemo> createState() => _CupertinoSegmentedControlDemoState();
 }
 
 class _CupertinoSegmentedControlDemoState extends State<CupertinoSegmentedControlDemo> {

dev/integration_tests/flutter_gallery/lib/demo/cupertino/cupertino_slider_demo.dart

@@ -12,7 +12,7 @@ class CupertinoSliderDemo extends StatefulWidget {
   static const String routeName = '/cupertino/slider';
 
   @override
-  _CupertinoSliderDemoState createState() => _CupertinoSliderDemoState();
+  State<CupertinoSliderDemo> createState() => _CupertinoSliderDemoState();
 }
 
 class _CupertinoSliderDemoState extends State<CupertinoSliderDemo> {

dev/integration_tests/flutter_gallery/lib/demo/cupertino/cupertino_switch_demo.dart

@@ -12,7 +12,7 @@ class CupertinoSwitchDemo extends StatefulWidget {
   static const String routeName = '/cupertino/switch';
 
   @override
-  _CupertinoSwitchDemoState createState() => _CupertinoSwitchDemoState();
+  State<CupertinoSwitchDemo> createState() => _CupertinoSwitchDemoState();
 }
 
 class _CupertinoSwitchDemoState extends State<CupertinoSwitchDemo> {

dev/integration_tests/flutter_gallery/lib/demo/cupertino/cupertino_text_field_demo.dart

@@ -10,7 +10,7 @@ class CupertinoTextFieldDemo extends StatefulWidget {
   static const String routeName = '/cupertino/text_fields';
 
   @override
-  _CupertinoTextFieldDemoState createState() {
+  State<CupertinoTextFieldDemo> createState() {
     return _CupertinoTextFieldDemoState();
   }
 }

dev/integration_tests/flutter_gallery/lib/demo/material/backdrop_demo.dart

@@ -244,7 +244,7 @@ class BackdropDemo extends StatefulWidget {
   static const String routeName = '/material/backdrop';
 
   @override
-  _BackdropDemoState createState() => _BackdropDemoState();
+  State<BackdropDemo> createState() => _BackdropDemoState();
 }
 
 class _BackdropDemoState extends State<BackdropDemo> with SingleTickerProviderStateMixin {

dev/integration_tests/flutter_gallery/lib/demo/material/banner_demo.dart

@@ -18,7 +18,7 @@ class BannerDemo extends StatefulWidget {
   static const String routeName = '/material/banner';
 
   @override
-  _BannerDemoState createState() => _BannerDemoState();
+  State<BannerDemo> createState() => _BannerDemoState();
 }
 
 class _BannerDemoState extends State<BannerDemo> {

dev/integration_tests/flutter_gallery/lib/demo/material/bottom_navigation_demo.dart

@@ -112,7 +112,7 @@ class BottomNavigationDemo extends StatefulWidget {
   static const String routeName = '/material/bottom_navigation';
 
   @override
-  _BottomNavigationDemoState createState() => _BottomNavigationDemoState();
+  State<BottomNavigationDemo> createState() => _BottomNavigationDemoState();
 }
 
 class _BottomNavigationDemoState extends State<BottomNavigationDemo>

dev/integration_tests/flutter_gallery/lib/demo/material/buttons_demo.dart

@@ -51,7 +51,7 @@ class ButtonsDemo extends StatefulWidget {
   static const String routeName = '/material/buttons';
 
   @override
-  _ButtonsDemoState createState() => _ButtonsDemoState();
+  State<ButtonsDemo> createState() => _ButtonsDemoState();
 }
 
 class _ButtonsDemoState extends State<ButtonsDemo> {

dev/integration_tests/flutter_gallery/lib/demo/material/cards_demo.dart

@@ -150,7 +150,7 @@ class SelectableTravelDestinationItem extends StatefulWidget {
   final ShapeBorder? shape;
 
   @override
-  _SelectableTravelDestinationItemState createState() => _SelectableTravelDestinationItemState();
+  State<SelectableTravelDestinationItem> createState() => _SelectableTravelDestinationItemState();
 }
 
 class _SelectableTravelDestinationItemState extends State<SelectableTravelDestinationItem> {
@@ -340,7 +340,7 @@ class CardsDemo extends StatefulWidget {
   static const String routeName = '/material/cards';
 
   @override
-  _CardsDemoState createState() => _CardsDemoState();
+  State<CardsDemo> createState() => _CardsDemoState();
 }
 
 class _CardsDemoState extends State<CardsDemo> {

dev/integration_tests/flutter_gallery/lib/demo/material/chip_demo.dart

@@ -140,7 +140,7 @@ class ChipDemo extends StatefulWidget {
   static const String routeName = '/material/chip';
 
   @override
-  _ChipDemoState createState() => _ChipDemoState();
+  State<ChipDemo> createState() => _ChipDemoState();
 }
 
 class _ChipDemoState extends State<ChipDemo> {

dev/integration_tests/flutter_gallery/lib/demo/material/data_table_demo.dart

@@ -147,7 +147,7 @@ class DataTableDemo extends StatefulWidget {
   static const String routeName = '/material/data-table';
 
   @override
-  _DataTableDemoState createState() => _DataTableDemoState();
+  State<DataTableDemo> createState() => _DataTableDemoState();
 }
 
 class _DataTableDemoState extends State<DataTableDemo> {

dev/integration_tests/flutter_gallery/lib/demo/material/date_and_time_picker_demo.dart

@@ -118,7 +118,7 @@ class DateAndTimePickerDemo extends StatefulWidget {
   static const String routeName = '/material/date-and-time-pickers';
 
   @override
-  _DateAndTimePickerDemoState createState() => _DateAndTimePickerDemoState();
+  State<DateAndTimePickerDemo> createState() => _DateAndTimePickerDemoState();
 }
 
 class _DateAndTimePickerDemoState extends State<DateAndTimePickerDemo> {

dev/integration_tests/flutter_gallery/lib/demo/material/drawer_demo.dart

@@ -18,7 +18,7 @@ class DrawerDemo extends StatefulWidget {
   static const String routeName = '/material/drawer';
 
   @override
-  _DrawerDemoState createState() => _DrawerDemoState();
+  State<DrawerDemo> createState() => _DrawerDemoState();
 }
 
 class _DrawerDemoState extends State<DrawerDemo> with TickerProviderStateMixin {

dev/integration_tests/flutter_gallery/lib/demo/material/expansion_panels_demo.dart

@@ -182,7 +182,7 @@ class ExpansionPanelsDemo extends StatefulWidget {
   static const String routeName = '/material/expansion_panels';
 
   @override
-  _ExpansionPanelsDemoState createState() => _ExpansionPanelsDemoState();
+  State<ExpansionPanelsDemo> createState() => _ExpansionPanelsDemoState();
 }
 
 class _ExpansionPanelsDemoState extends State<ExpansionPanelsDemo> {

dev/integration_tests/flutter_gallery/lib/demo/material/grid_list_demo.dart

@@ -43,7 +43,7 @@ class GridPhotoViewer extends StatefulWidget {
   final Photo? photo;
 
   @override
-  _GridPhotoViewerState createState() => _GridPhotoViewerState();
+  State<GridPhotoViewer> createState() => _GridPhotoViewerState();
 }
 
 class _GridTitleText extends StatelessWidget {

dev/integration_tests/flutter_gallery/lib/demo/material/list_demo.dart

@@ -26,7 +26,7 @@ class ListDemo extends StatefulWidget {
   static const String routeName = '/material/list';
 
   @override
-  _ListDemoState createState() => _ListDemoState();
+  State<ListDemo> createState() => _ListDemoState();
 }
 
 class _ListDemoState extends State<ListDemo> {

dev/integration_tests/flutter_gallery/lib/demo/material/persistent_bottom_sheet_demo.dart

@@ -12,7 +12,7 @@ class PersistentBottomSheetDemo extends StatefulWidget {
   static const String routeName = '/material/persistent-bottom-sheet';
 
   @override
-  _PersistentBottomSheetDemoState createState() => _PersistentBottomSheetDemoState();
+  State<PersistentBottomSheetDemo> createState() => _PersistentBottomSheetDemoState();
 }
 
 class _PersistentBottomSheetDemoState extends State<PersistentBottomSheetDemo> {

dev/integration_tests/flutter_gallery/lib/demo/material/progress_indicator_demo.dart

@@ -12,7 +12,7 @@ class ProgressIndicatorDemo extends StatefulWidget {
   static const String routeName = '/material/progress-indicator';
 
   @override
-  _ProgressIndicatorDemoState createState() => _ProgressIndicatorDemoState();
+  State<ProgressIndicatorDemo> createState() => _ProgressIndicatorDemoState();
 }
 
 class _ProgressIndicatorDemoState extends State<ProgressIndicatorDemo> with SingleTickerProviderStateMixin {

dev/integration_tests/flutter_gallery/lib/demo/material/reorderable_list_demo.dart

@@ -23,7 +23,7 @@ class ReorderableListDemo extends StatefulWidget {
   static const String routeName = '/material/reorderable-list';
 
   @override
-  _ListDemoState createState() => _ListDemoState();
+  State<ReorderableListDemo> createState() => _ListDemoState();
 }
 
 class _ListItem {

dev/integration_tests/flutter_gallery/lib/demo/material/search_demo.dart

@@ -12,7 +12,7 @@ class SearchDemo extends StatefulWidget {
   static const String routeName = '/material/search';
 
   @override
-  _SearchDemoState createState() => _SearchDemoState();
+  State<SearchDemo> createState() => _SearchDemoState();
 }
 
 class _SearchDemoState extends State<SearchDemo> {

dev/integration_tests/flutter_gallery/lib/demo/material/selection_controls_demo.dart

@@ -33,7 +33,7 @@ class SelectionControlsDemo extends StatefulWidget {
   static const String routeName = '/material/selection-controls';
 
   @override
-  _SelectionControlsDemoState createState() => _SelectionControlsDemoState();
+  State<SelectionControlsDemo> createState() => _SelectionControlsDemoState();
 }
 
 class _SelectionControlsDemoState extends State<SelectionControlsDemo> {

dev/integration_tests/flutter_gallery/lib/demo/material/slider_demo.dart

@@ -14,7 +14,7 @@ class SliderDemo extends StatefulWidget {
   static const String routeName = '/material/slider';
 
   @override
-  _SliderDemoState createState() => _SliderDemoState();
+  State<SliderDemo> createState() => _SliderDemoState();
 }
 
 Path _downTriangle(double size, Offset thumbCenter, { bool invert = false }) {

dev/integration_tests/flutter_gallery/lib/demo/material/snack_bar_demo.dart

@@ -24,7 +24,7 @@ class SnackBarDemo extends StatefulWidget {
   static const String routeName = '/material/snack-bar';
 
   @override
-  _SnackBarDemoState createState() => _SnackBarDemoState();
+  State<SnackBarDemo> createState() => _SnackBarDemoState();
 }
 
 class _SnackBarDemoState extends State<SnackBarDemo> {

dev/integration_tests/flutter_gallery/lib/demo/material/tabs_fab_demo.dart

@@ -40,7 +40,7 @@ class TabsFabDemo extends StatefulWidget {
   static const String routeName = '/material/tabs-fab';
 
   @override
-  _TabsFabDemoState createState() => _TabsFabDemoState();
+  State<TabsFabDemo> createState() => _TabsFabDemoState();
 }
 
 class _TabsFabDemoState extends State<TabsFabDemo> with SingleTickerProviderStateMixin {

dev/integration_tests/flutter_gallery/lib/demo/material/text_form_field_demo.dart

@@ -45,7 +45,7 @@ class PasswordField extends StatefulWidget {
   final ValueChanged<String>? onFieldSubmitted;
 
   @override
-  _PasswordFieldState createState() => _PasswordFieldState();
+  State<PasswordField> createState() => _PasswordFieldState();
 }
 
 class _PasswordFieldState extends State<PasswordField> {

dev/integration_tests/flutter_gallery/lib/demo/pesto_demo.dart

@@ -71,7 +71,7 @@ class RecipeGridPage extends StatefulWidget {
   final List<Recipe?>? recipes;
 
   @override
-  _RecipeGridPageState createState() => _RecipeGridPageState();
+  State<RecipeGridPage> createState() => _RecipeGridPageState();
 }
 
 class _RecipeGridPageState extends State<RecipeGridPage> {
@@ -195,7 +195,7 @@ class PestoLogo extends StatefulWidget {
   final double? t;
 
   @override
-  _PestoLogoState createState() => _PestoLogoState();
+  State<PestoLogo> createState() => _PestoLogoState();
 }
 
 class _PestoLogoState extends State<PestoLogo> {
@@ -319,7 +319,7 @@ class RecipePage extends StatefulWidget {
   final Recipe? recipe;
 
   @override
-  _RecipePageState createState() => _RecipePageState();
+  State<RecipePage> createState() => _RecipePageState();
 }
 
 class _RecipePageState extends State<RecipePage> {

dev/integration_tests/flutter_gallery/lib/demo/shrine/app.dart

@@ -16,7 +16,7 @@ class ShrineApp extends StatefulWidget {
   const ShrineApp({Key? key}) : super(key: key);
 
   @override
-  _ShrineAppState createState() => _ShrineAppState();
+  State<ShrineApp> createState() => _ShrineAppState();
 }
 
 class _ShrineAppState extends State<ShrineApp> with SingleTickerProviderStateMixin {

dev/integration_tests/flutter_gallery/lib/demo/shrine/backdrop.dart

@@ -213,7 +213,7 @@ class Backdrop extends StatefulWidget {
   final AnimationController controller;
 
   @override
-  _BackdropState createState() => _BackdropState();
+  State<Backdrop> createState() => _BackdropState();
 }
 
 class _BackdropState extends State<Backdrop> with SingleTickerProviderStateMixin {

dev/integration_tests/flutter_gallery/lib/demo/shrine/expanding_bottom_sheet.dart

@@ -30,10 +30,10 @@ class ExpandingBottomSheet extends StatefulWidget {
   final AnimationController hideController;
 
   @override
-  _ExpandingBottomSheetState createState() => _ExpandingBottomSheetState();
+  ExpandingBottomSheetState createState() => ExpandingBottomSheetState();
 
-  static _ExpandingBottomSheetState? of(BuildContext context, {bool isNullOk = false}) {
-    final _ExpandingBottomSheetState? result = context.findAncestorStateOfType<_ExpandingBottomSheetState>();
+  static ExpandingBottomSheetState? of(BuildContext context, {bool isNullOk = false}) {
+    final ExpandingBottomSheetState? result = context.findAncestorStateOfType<ExpandingBottomSheetState>();
     if (isNullOk || result != null) {
       return result;
     }
@@ -97,7 +97,7 @@ double _getPeakPoint({required double begin, required double end}) {
   return begin + (end - begin) * _kPeakVelocityProgress;
 }
 
-class _ExpandingBottomSheetState extends State<ExpandingBottomSheet> with TickerProviderStateMixin {
+class ExpandingBottomSheetState extends State<ExpandingBottomSheet> with TickerProviderStateMixin {
   final GlobalKey _expandingBottomSheetKey = GlobalKey(debugLabel: 'Expanding bottom sheet');
 
   // The width of the Material, calculated by _widthFor() & based on the number
@@ -405,7 +405,7 @@ class ProductThumbnailRow extends StatefulWidget {
   const ProductThumbnailRow({Key? key}) : super(key: key);
 
   @override
-  _ProductThumbnailRowState createState() => _ProductThumbnailRowState();
+  State<ProductThumbnailRow> createState() => _ProductThumbnailRowState();
 }
 
 class _ProductThumbnailRowState extends State<ProductThumbnailRow> {

dev/integration_tests/flutter_gallery/lib/demo/shrine/login.dart

@@ -10,7 +10,7 @@ class LoginPage extends StatefulWidget {
   const LoginPage({Key? key}) : super(key: key);
 
   @override
-  _LoginPageState createState() => _LoginPageState();
+  State<LoginPage> createState() => _LoginPageState();
 }
 
 class _LoginPageState extends State<LoginPage> {

dev/integration_tests/flutter_gallery/lib/demo/shrine/shopping_cart.dart

@@ -16,7 +16,7 @@ class ShoppingCartPage extends StatefulWidget {
   const ShoppingCartPage({Key? key}) : super(key: key);
 
   @override
-  _ShoppingCartPageState createState() => _ShoppingCartPageState();
+  State<ShoppingCartPage> createState() => _ShoppingCartPageState();
 }
 
 class _ShoppingCartPageState extends State<ShoppingCartPage> {

dev/integration_tests/flutter_gallery/lib/demo/transformations/transformations_demo.dart

@@ -13,7 +13,8 @@ class TransformationsDemo extends StatefulWidget {
 
   static const String routeName = '/transformations';
 
-  @override _TransformationsDemoState createState() => _TransformationsDemoState();
+  @override
+  State<TransformationsDemo> createState() => _TransformationsDemoState();
 }
 class _TransformationsDemoState extends State<TransformationsDemo> {
   // The radius of a hexagon tile in pixels.

dev/integration_tests/flutter_gallery/lib/demo/transformations/transformations_demo_gesture_transformable.dart

@@ -117,7 +117,8 @@ class GestureTransformable extends StatefulWidget {
   final double? initialScale;
   final double? initialRotation;
 
-  @override _GestureTransformableState createState() => _GestureTransformableState();
+  @override
+  State<GestureTransformable> createState() => _GestureTransformableState();
 }
 
 // A single user event can only represent one of these gestures. The user can't

dev/integration_tests/flutter_gallery/lib/demo/video_demo.dart

@@ -98,7 +98,7 @@ class VideoPlayerLoading extends StatefulWidget {
   final VideoPlayerController? controller;
 
   @override
-  _VideoPlayerLoadingState createState() => _VideoPlayerLoadingState();
+  State<VideoPlayerLoading> createState() => _VideoPlayerLoadingState();
 }
 
 class _VideoPlayerLoadingState extends State<VideoPlayerLoading> {
@@ -212,7 +212,7 @@ class FadeAnimation extends StatefulWidget {
   final Duration duration;
 
   @override
-  _FadeAnimationState createState() => _FadeAnimationState();
+  State<FadeAnimation> createState() => _FadeAnimationState();
 }
 
 class _FadeAnimationState extends State<FadeAnimation> with SingleTickerProviderStateMixin {
@@ -275,7 +275,7 @@ class ConnectivityOverlay extends StatefulWidget {
   final Completer<void>? connectedCompleter;
 
   @override
-  _ConnectivityOverlayState createState() => _ConnectivityOverlayState();
+  State<ConnectivityOverlay> createState() => _ConnectivityOverlayState();
 }
 
 class _ConnectivityOverlayState extends State<ConnectivityOverlay> {
@@ -348,7 +348,7 @@ class VideoDemo extends StatefulWidget {
   static const String routeName = '/video';
 
   @override
-  _VideoDemoState createState() => _VideoDemoState();
+  State<VideoDemo> createState() => _VideoDemoState();
 }
 
 final DeviceInfoPlugin deviceInfoPlugin = DeviceInfoPlugin();

dev/integration_tests/flutter_gallery/lib/gallery/app.dart

@@ -39,7 +39,7 @@ class GalleryApp extends StatefulWidget {
   final bool testMode;
 
   @override
-  _GalleryAppState createState() => _GalleryAppState();
+  State<GalleryApp> createState() => _GalleryAppState();
 }
 
 class _GalleryAppState extends State<GalleryApp> {

dev/integration_tests/flutter_gallery/lib/gallery/backdrop.dart

@@ -196,7 +196,7 @@ class Backdrop extends StatefulWidget {
   final Widget? backLayer;
 
   @override
-  _BackdropState createState() => _BackdropState();
+  State<Backdrop> createState() => _BackdropState();
 }
 
 class _BackdropState extends State<Backdrop> with SingleTickerProviderStateMixin {

dev/integration_tests/flutter_gallery/lib/gallery/home.dart

@@ -278,7 +278,7 @@ class GalleryHome extends StatefulWidget {
   static bool showPreviewBanner = true;
 
   @override
-  _GalleryHomeState createState() => _GalleryHomeState();
+  State<GalleryHome> createState() => _GalleryHomeState();
 }
 
 class _GalleryHomeState extends State<GalleryHome> with SingleTickerProviderStateMixin {

dev/integration_tests/hybrid_android_views/lib/nested_view_event_page.dart

@@ -33,9 +33,8 @@ enum _LastTestStatus {
 }
 
 class NestedViewEventBodyState extends State<NestedViewEventBody> {
-
   MethodChannel viewChannel;
-  _LastTestStatus lastTestStatus = _LastTestStatus.pending;
+  _LastTestStatus _lastTestStatus = _LastTestStatus.pending;
   String lastError;
   int id;
   int nestedViewClickCount = 0;
@@ -58,7 +57,7 @@ class NestedViewEventBodyState extends State<NestedViewEventBody> {
                   onPlatformViewCreated: onPlatformViewCreated,
                 ) : null,
           ),
-          if (lastTestStatus != _LastTestStatus.pending) _statusWidget(),
+          if (_lastTestStatus != _LastTestStatus.pending) _statusWidget(),
           if (viewChannel != null) ... <Widget>[
             ElevatedButton(
               key: const ValueKey<String>('ShowAlertDialog'),
@@ -96,34 +95,34 @@ class NestedViewEventBodyState extends State<NestedViewEventBody> {
   }
 
   Widget _statusWidget() {
-    assert(lastTestStatus != _LastTestStatus.pending);
-    final String message = lastTestStatus == _LastTestStatus.success ? 'Success' : lastError;
+    assert(_lastTestStatus != _LastTestStatus.pending);
+    final String message = _lastTestStatus == _LastTestStatus.success ? 'Success' : lastError;
     return Container(
-      color: lastTestStatus == _LastTestStatus.success ? Colors.green : Colors.red,
+      color: _lastTestStatus == _LastTestStatus.success ? Colors.green : Colors.red,
       child: Text(
         message,
         key: const ValueKey<String>('Status'),
         style: TextStyle(
-          color: lastTestStatus == _LastTestStatus.error ? Colors.yellow : null,
+          color: _lastTestStatus == _LastTestStatus.error ? Colors.yellow : null,
         ),
       ),
     );
   }
 
   Future<void> onShowAlertDialogPressed() async {
-    if (lastTestStatus != _LastTestStatus.pending) {
+    if (_lastTestStatus != _LastTestStatus.pending) {
       setState(() {
-        lastTestStatus = _LastTestStatus.pending;
+        _lastTestStatus = _LastTestStatus.pending;
       });
     }
     try {
       await viewChannel.invokeMethod<void>('showAndHideAlertDialog');
       setState(() {
-        lastTestStatus = _LastTestStatus.success;
+        _lastTestStatus = _LastTestStatus.success;
       });
     } catch(e) {
       setState(() {
-        lastTestStatus = _LastTestStatus.error;
+        _lastTestStatus = _LastTestStatus.error;
         lastError = '$e';
       });
     }
@@ -143,7 +142,7 @@ class NestedViewEventBodyState extends State<NestedViewEventBody> {
       });
     } catch(e) {
       setState(() {
-        lastTestStatus = _LastTestStatus.error;
+        _lastTestStatus = _LastTestStatus.error;
         lastError = '$e';
       });
     }

dev/integration_tests/ios_add2app_life_cycle/flutterapp/lib/main.dart

@@ -32,7 +32,7 @@ class LifeCycleSpy extends StatefulWidget {
   const LifeCycleSpy({Key? key}) : super(key: key);
 
   @override
-  _LifeCycleSpyState createState() => _LifeCycleSpyState();
+  State<LifeCycleSpy> createState() => _LifeCycleSpyState();
 }
 
 class _LifeCycleSpyState extends State<LifeCycleSpy> with WidgetsBindingObserver {

dev/integration_tests/ios_app_with_extensions/lib/main.dart

@@ -46,7 +46,7 @@ class MyHomePage extends StatefulWidget {
   final String? title;
 
   @override
-  _MyHomePageState createState() => _MyHomePageState();
+  State<MyHomePage> createState() => _MyHomePageState();
 }
 
 class _MyHomePageState extends State<MyHomePage> {

dev/integration_tests/ios_platform_view_tests/lib/main.dart

@@ -34,7 +34,7 @@ class MyHomePage extends StatefulWidget {
   final String? title;
 
   @override
-  _MyHomePageState createState() => _MyHomePageState();
+  State<MyHomePage> createState() => _MyHomePageState();
 }
 
 class _MyHomePageState extends State<MyHomePage> {

dev/integration_tests/platform_interaction/lib/main.dart

@@ -19,7 +19,7 @@ class TestApp extends StatefulWidget {
   const TestApp({Key? key}) : super(key: key);
 
   @override
-  _TestAppState createState() => _TestAppState();
+  State<TestApp> createState() => _TestAppState();
 }
 
 class _TestAppState extends State<TestApp> {

dev/integration_tests/ui/lib/keyboard_resize.dart

@@ -32,7 +32,7 @@ class MyHomePage extends StatefulWidget {
   const MyHomePage({Key? key}) : super(key: key);
 
   @override
-  _MyHomePageState createState() => _MyHomePageState();
+  State<MyHomePage> createState() => _MyHomePageState();
 }
 
 class _MyHomePageState extends State<MyHomePage> {

dev/integration_tests/ui/lib/keyboard_textfield.dart

@@ -30,7 +30,7 @@ class MyHomePage extends StatefulWidget {
   const MyHomePage({Key? key}) : super(key: key);
 
   @override
-  _MyHomePageState createState() => _MyHomePageState();
+  State<MyHomePage> createState() => _MyHomePageState();
 }
 
 class _MyHomePageState extends State<MyHomePage> {

dev/integration_tests/web_e2e_tests/lib/text_editing_main.dart

@@ -25,7 +25,7 @@ class MyHomePage extends StatefulWidget {
   final String? title;
 
   @override
-  _MyHomePageState createState() => _MyHomePageState();
+  State<MyHomePage> createState() => _MyHomePageState();
 }
 
 class _MyHomePageState extends State<MyHomePage> {

dev/manual_tests/lib/actions.dart

@@ -299,7 +299,7 @@ class DemoButton extends StatefulWidget {
   final String name;
 
   @override
-  _DemoButtonState createState() => _DemoButtonState();
+  State<DemoButton> createState() => _DemoButtonState();
 }
 
 class _DemoButtonState extends State<DemoButton> {
@@ -351,7 +351,7 @@ class FocusDemo extends StatefulWidget {
   static GlobalKey appKey = GlobalKey();
 
   @override
-  _FocusDemoState createState() => _FocusDemoState();
+  State<FocusDemo> createState() => _FocusDemoState();
 }
 
 class _FocusDemoState extends State<FocusDemo> {

dev/manual_tests/lib/density.dart

@@ -41,7 +41,7 @@ class MyHomePage extends StatefulWidget {
   final String title;
 
   @override
-  _MyHomePageState createState() => _MyHomePageState();
+  State<MyHomePage> createState() => _MyHomePageState();
 }
 
 class OptionModel extends ChangeNotifier {
@@ -139,7 +139,7 @@ class Options extends StatefulWidget {
   final OptionModel model;
 
   @override
-  _OptionsState createState() => _OptionsState();
+  State<Options> createState() => _OptionsState();
 }
 
 class _OptionsState extends State<Options> {

dev/manual_tests/lib/focus.dart

@@ -20,7 +20,7 @@ class DemoButton extends StatefulWidget {
   final bool autofocus;
 
   @override
-  _DemoButtonState createState() => _DemoButtonState();
+  State<DemoButton> createState() => _DemoButtonState();
 }
 
 class _DemoButtonState extends State<DemoButton> {
@@ -77,7 +77,7 @@ class FocusDemo extends StatefulWidget {
   const FocusDemo({Key key}) : super(key: key);
 
   @override
-  _FocusDemoState createState() => _FocusDemoState();
+  State<FocusDemo> createState() => _FocusDemoState();
 }
 
 class _FocusDemoState extends State<FocusDemo> {

dev/manual_tests/lib/hover.dart

@@ -33,7 +33,7 @@ class HoverDemo extends StatefulWidget {
   const HoverDemo({Key key}) : super(key: key);
 
   @override
-  _HoverDemoState createState() => _HoverDemoState();
+  State<HoverDemo> createState() => _HoverDemoState();
 }
 
 class _HoverDemoState extends State<HoverDemo> {

dev/manual_tests/lib/material_arc.dart

@@ -409,7 +409,7 @@ class AnimationDemo extends StatefulWidget {
   const AnimationDemo({ Key key }) : super(key: key);
 
   @override
-  _AnimationDemoState createState() => _AnimationDemoState();
+  State<AnimationDemo> createState() => _AnimationDemoState();
 }
 
 class _AnimationDemoState extends State<AnimationDemo> with TickerProviderStateMixin {

dev/manual_tests/lib/raw_keyboard.dart

@@ -23,7 +23,7 @@ class RawKeyboardDemo extends StatefulWidget {
   const RawKeyboardDemo({Key key}) : super(key: key);
 
   @override
-  _HardwareKeyDemoState createState() => _HardwareKeyDemoState();
+  State<RawKeyboardDemo> createState() => _HardwareKeyDemoState();
 }
 
 class _HardwareKeyDemoState extends State<RawKeyboardDemo> {

dev/manual_tests/lib/text.dart

@@ -29,7 +29,7 @@ class Home extends StatefulWidget {
   const Home({ Key key }) : super(key: key);
 
   @override
-  _HomeState createState() => _HomeState();
+  State<Home> createState() => _HomeState();
 }
 
 class _HomeState extends State<Home> {
@@ -124,7 +124,7 @@ class Fuzzer extends StatefulWidget {
   final int seed;
 
   @override
-  _FuzzerState createState() => _FuzzerState();
+  State<Fuzzer> createState() => _FuzzerState();
 }
 
 class _FuzzerState extends State<Fuzzer> with SingleTickerProviderStateMixin {
@@ -539,7 +539,7 @@ class Underlines extends StatefulWidget {
   const Underlines({ Key key }) : super(key: key);
 
   @override
-  _UnderlinesState createState() => _UnderlinesState();
+  State<Underlines> createState() => _UnderlinesState();
 }
 
 class _UnderlinesState extends State<Underlines> {
@@ -644,7 +644,7 @@ class Fallback extends StatefulWidget {
   const Fallback({ Key key }) : super(key: key);
 
   @override
-  _FallbackState createState() => _FallbackState();
+  State<Fallback> createState() => _FallbackState();
 }
 
 class _FallbackState extends State<Fallback> {
@@ -739,7 +739,7 @@ class Bidi extends StatefulWidget {
   const Bidi({ Key key }) : super(key: key);
 
   @override
-  _BidiState createState() => _BidiState();
+  State<Bidi> createState() => _BidiState();
 }
 
 class _BidiState extends State<Bidi> {
@@ -816,7 +816,7 @@ class Zalgo extends StatefulWidget {
   final int seed;
 
   @override
-  _ZalgoState createState() => _ZalgoState();
+  State<Zalgo> createState() => _ZalgoState();
 }
 
 class _ZalgoState extends State<Zalgo> with SingleTickerProviderStateMixin {
@@ -923,7 +923,7 @@ class Painting extends StatefulWidget {
   final int seed;
 
   @override
-  _PaintingState createState() => _PaintingState();
+  State<Painting> createState() => _PaintingState();
 }
 
 class _PaintingState extends State<Painting> with SingleTickerProviderStateMixin {

dev/snippets/config/templates/stateful_widget.tmpl

@@ -30,7 +30,7 @@ class MyStatefulWidget extends StatefulWidget {
   const MyStatefulWidget({Key? key}) : super(key: key);
 
   @override
-  _MyStatefulWidgetState createState() => _MyStatefulWidgetState();
+  State<MyStatefulWidget> createState() => _MyStatefulWidgetState();
 }
 
 /// This is the private State class that goes with MyStatefulWidget.

dev/snippets/config/templates/stateful_widget_cupertino.tmpl

@@ -31,7 +31,7 @@ class MyStatefulWidget extends StatefulWidget {
   const MyStatefulWidget({Key? key}) : super(key: key);
 
   @override
-  _MyStatefulWidgetState createState() => _MyStatefulWidgetState();
+  State<MyStatefulWidget> createState() => _MyStatefulWidgetState();
 }
 
 /// This is the private State class that goes with MyStatefulWidget.

dev/snippets/config/templates/stateful_widget_cupertino_page_scaffold.tmpl

@@ -34,7 +34,7 @@ class MyStatefulWidget extends StatefulWidget {
   const MyStatefulWidget({Key? key}) : super(key: key);
 
   @override
-  _MyStatefulWidgetState createState() => _MyStatefulWidgetState();
+  State<MyStatefulWidget> createState() => _MyStatefulWidgetState();
 }
 
 /// This is the private State class that goes with MyStatefulWidget.

dev/snippets/config/templates/stateful_widget_cupertino_ticker.tmpl

@@ -31,7 +31,7 @@ class MyStatefulWidget extends StatefulWidget {
   const MyStatefulWidget({Key? key}) : super(key: key);
 
   @override
-  _MyStatefulWidgetState createState() => _MyStatefulWidgetState();
+  State<MyStatefulWidget> createState() => _MyStatefulWidgetState();
 }
 
 /// This is the private State class that goes with MyStatefulWidget.

dev/snippets/config/templates/stateful_widget_material.tmpl

@@ -31,7 +31,7 @@ class MyStatefulWidget extends StatefulWidget {
   const MyStatefulWidget({Key? key}) : super(key: key);
 
   @override
-  _MyStatefulWidgetState createState() => _MyStatefulWidgetState();
+  State<MyStatefulWidget> createState() => _MyStatefulWidgetState();
 }
 
 /// This is the private State class that goes with MyStatefulWidget.

dev/snippets/config/templates/stateful_widget_material_ticker.tmpl

@@ -31,7 +31,7 @@ class MyStatefulWidget extends StatefulWidget {
   const MyStatefulWidget({Key? key}) : super(key: key);
 
   @override
-  _MyStatefulWidgetState createState() => _MyStatefulWidgetState();
+  State<MyStatefulWidget> createState() => _MyStatefulWidgetState();
 }
 
 /// This is the private State class that goes with MyStatefulWidget.

dev/snippets/config/templates/stateful_widget_restoration.tmpl

@@ -34,7 +34,7 @@ class MyStatefulWidget extends StatefulWidget {
   final String? restorationId;
 
   @override
-  _MyStatefulWidgetState createState() => _MyStatefulWidgetState();
+  State<MyStatefulWidget> createState() => _MyStatefulWidgetState();
 }
 
 /// This is the private State class that goes with MyStatefulWidget.

dev/snippets/config/templates/stateful_widget_restoration_cupertino.tmpl

@@ -34,7 +34,7 @@ class MyStatefulWidget extends StatefulWidget {
   final String? restorationId;
 
   @override
-  _MyStatefulWidgetState createState() => _MyStatefulWidgetState();
+  State<MyStatefulWidget> createState() => _MyStatefulWidgetState();
 }
 
 /// This is the private State class that goes with MyStatefulWidget.

dev/snippets/config/templates/stateful_widget_restoration_material.tmpl

@@ -34,7 +34,7 @@ class MyStatefulWidget extends StatefulWidget {
   final String? restorationId;
 
   @override
-  _MyStatefulWidgetState createState() => _MyStatefulWidgetState();
+  State<MyStatefulWidget> createState() => _MyStatefulWidgetState();
 }
 
 /// This is the private State class that goes with MyStatefulWidget.

dev/snippets/config/templates/stateful_widget_scaffold.tmpl

@@ -34,7 +34,7 @@ class MyStatefulWidget extends StatefulWidget {
   const MyStatefulWidget({Key? key}) : super(key: key);
 
   @override
-  _MyStatefulWidgetState createState() => _MyStatefulWidgetState();
+  State<MyStatefulWidget> createState() => _MyStatefulWidgetState();
 }
 
 /// This is the private State class that goes with MyStatefulWidget.

dev/snippets/config/templates/stateful_widget_scaffold_center.tmpl

@@ -36,7 +36,7 @@ class MyStatefulWidget extends StatefulWidget {
   const MyStatefulWidget({Key? key}) : super(key: key);
 
   @override
-  _MyStatefulWidgetState createState() => _MyStatefulWidgetState();
+  State<MyStatefulWidget> createState() => _MyStatefulWidgetState();
 }
 
 /// This is the private State class that goes with MyStatefulWidget.

dev/snippets/config/templates/stateful_widget_scaffold_center_freeform_state.tmpl

@@ -36,7 +36,7 @@ class MyStatefulWidget extends StatefulWidget {
   const MyStatefulWidget({Key? key}) : super(key: key);
 
   @override
-  _MyStatefulWidgetState createState() => _MyStatefulWidgetState();
+  State<MyStatefulWidget> createState() => _MyStatefulWidgetState();
 }
 
 /// This is the private State class that goes with MyStatefulWidget.

dev/snippets/config/templates/stateful_widget_ticker.tmpl

@@ -30,7 +30,7 @@ class MyStatefulWidget extends StatefulWidget {
   const MyStatefulWidget({Key? key}) : super(key: key);
 
   @override
-  _MyStatefulWidgetState createState() => _MyStatefulWidgetState();
+  State<MyStatefulWidget> createState() => _MyStatefulWidgetState();
 }
 
 /// This is the private State class that goes with MyStatefulWidget.

dev/snippets/lib/snippets.dart

@@ -60,7 +60,7 @@ class SnippetGenerator {
   /// Injects the [injections] into the [template], and turning the
   /// "description" injection into a comment. Only used for
   /// [SnippetType.sample] snippets.
-  String interpolateTemplate(List<_ComponentTuple> injections, String template, Map<String, Object?> metadata) {
+  String _interpolateTemplate(List<_ComponentTuple> injections, String template, Map<String, Object?> metadata) {
     final RegExp moustacheRegExp = RegExp('{{([^}]+)}}');
     final String interpolated = template.replaceAllMapped(moustacheRegExp, (Match match) {
       if (match[1] == 'description') {
@@ -158,7 +158,7 @@ class SnippetGenerator {
   ///
   /// Takes into account the [type] and doesn't substitute in the id and the app
   /// if not a [SnippetType.sample] snippet.
-  String interpolateSkeleton(
+  String _interpolateSkeleton(
     SnippetType type,
     List<_ComponentTuple> injections,
     String skeleton,
@@ -215,7 +215,7 @@ class SnippetGenerator {
 
   /// Parses the input for the various code and description segments, and
   /// returns them in the order found.
-  List<_ComponentTuple> parseInput(String input) {
+  List<_ComponentTuple> _parseInput(String input) {
     bool inCodeBlock = false;
     input = input.trim();
     final List<String> description = <String>[];
@@ -298,7 +298,7 @@ class SnippetGenerator {
     assert(template != null || type != SnippetType.sample);
     assert(metadata['id'] != null);
     assert(!showDartPad || type == SnippetType.sample, 'Only application samples work with dartpad.');
-    final List<_ComponentTuple> snippetData = parseInput(_loadFileAsUtf8(input));
+    final List<_ComponentTuple> snippetData = _parseInput(_loadFileAsUtf8(input));
     switch (type) {
       case SnippetType.sample:
         final Directory templatesDir = configuration.templatesDirectory;
@@ -312,7 +312,7 @@ class SnippetGenerator {
           exit(1);
         }
         final String templateContents = _loadFileAsUtf8(templateFile);
-        String app = interpolateTemplate(snippetData, templateContents, metadata);
+        String app = _interpolateTemplate(snippetData, templateContents, metadata);
 
         try {
           app = formatter.format(app);
@@ -343,6 +343,6 @@ class SnippetGenerator {
     }
     final String skeleton =
         _loadFileAsUtf8(configuration.getHtmlSkeletonFile(type, showDartPad: showDartPad));
-    return interpolateSkeleton(type, snippetData, skeleton, metadata);
+    return _interpolateSkeleton(type, snippetData, skeleton, metadata);
   }
 }

dev/tools/vitool/lib/vitool.dart

@@ -206,7 +206,7 @@ List<SvgPath> _interpretSvgGroup(List<XmlNode> children, _Transform transform) {
     final XmlElement element = node as XmlElement;
 
     if (element.name.local == 'path') {
-      paths.add(SvgPath.fromElement(element).applyTransform(transform));
+      paths.add(SvgPath.fromElement(element)._applyTransform(transform));
     }
 
     if (element.name.local == 'g') {
@@ -313,9 +313,9 @@ class SvgPath {
     return SvgPath(id, commands);
   }
 
-  SvgPath applyTransform(_Transform transform) {
+  SvgPath _applyTransform(_Transform transform) {
     final List<SvgPathCommand> transformedCommands =
-      commands.map<SvgPathCommand>((SvgPathCommand c) => c.applyTransform(transform)).toList();
+      commands.map<SvgPathCommand>((SvgPathCommand c) => c._applyTransform(transform)).toList();
     return SvgPath(id, transformedCommands, opacity: opacity * transform.opacity);
   }
 
@@ -359,7 +359,7 @@ class SvgPathCommand {
   /// List of points used by this command.
   final List<Point<double>> points;
 
-  SvgPathCommand applyTransform(_Transform transform) {
+  SvgPathCommand _applyTransform(_Transform transform) {
     final List<Point<double>> transformedPoints =
     _vector3ArrayToPoints(
         transform.transformMatrix.applyToVector3Array(

examples/flutter_view/lib/main.dart

@@ -29,7 +29,7 @@ class MyHomePage extends StatefulWidget {
   const MyHomePage({Key? key}) : super(key: key);
 
   @override
-  _MyHomePageState createState() => _MyHomePageState();
+  State<MyHomePage> createState() => _MyHomePageState();
 }
 
 class _MyHomePageState extends State<MyHomePage> {

examples/image_list/lib/main.dart

@@ -146,7 +146,7 @@ class MyHomePage extends StatefulWidget {
   final int port;
 
   @override
-  _MyHomePageState createState() => _MyHomePageState();
+  State<MyHomePage> createState() => _MyHomePageState();
 }
 
 class _MyHomePageState extends State<MyHomePage> with TickerProviderStateMixin {

examples/layers/services/lifecycle.dart

@@ -8,7 +8,7 @@ class LifecycleWatcher extends StatefulWidget {
   const LifecycleWatcher({ Key? key }) : super(key: key);
 
   @override
-  _LifecycleWatcherState createState() => _LifecycleWatcherState();
+  State<LifecycleWatcher> createState() => _LifecycleWatcherState();
 }
 
 class _LifecycleWatcherState extends State<LifecycleWatcher>

examples/layers/widgets/spinning_square.dart

@@ -8,7 +8,7 @@ class SpinningSquare extends StatefulWidget {
   const SpinningSquare({Key? key}) : super(key: key);
 
   @override
-  _SpinningSquareState createState() => _SpinningSquareState();
+  State<SpinningSquare> createState() => _SpinningSquareState();
 }
 
 class _SpinningSquareState extends State<SpinningSquare> with SingleTickerProviderStateMixin {

examples/layers/widgets/styled_text.dart

@@ -78,7 +78,7 @@ class StyledTextDemo extends StatefulWidget {
   const StyledTextDemo({Key? key}) : super(key: key);
 
   @override
-  _StyledTextDemoState createState() => _StyledTextDemoState();
+  State<StyledTextDemo> createState() => _StyledTextDemoState();
 }
 
 class _StyledTextDemoState extends State<StyledTextDemo> {