Fresh Flutter项目有错误:未定义函数"runApp" [英] Fresh Flutter project has error: The function 'runApp' isn't defined

问题描述

我正在尝试使用 flutter创建app_name 来测试抖动，并使用Android Studio和VS Code，我未定义 runApp 上的错误，并且实际上没有任何地方在flutter库中，我可以看到它正在定义.

I'm trying to test flutter with flutter create app_name and using Android Studio and VS Code I get the error on runApp isn't defined, and indeed no where in the flutter library I can see this is being defined.

奇怪的是，我第一次创建模板应用程序时，它在导入库中有一个不同的模板和更多行，但是在第二次尝试后，导入行仅限于:当然不包含 runApp()

Strangely, first time I created a template app it had a different template and more lines at import library but after second attempt the import line is only one limited to: import 'package:flutter/material.dart'; which of course does not include runApp()

import 'package:flutter/material.dart';


void main() => runApp(new MyApp());

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        // This is the theme of your application.
        //
        // Try running your application with "flutter run". You'll see the
        // application has a blue toolbar. Then, without quitting the app, try
        // changing the primarySwatch below to Colors.green and then invoke
        // "hot reload" (press "r" in the console where you ran "flutter run",
        // or simply save your changes to "hot reload" in a Flutter IDE).
        // Notice that the counter didn't reset back to zero; the application
        // is not restarted.
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

错误

C:\Works\flutter_udemy_course_blank2>flutter run
Using hardware rendering with device AOSP on IA Emulator. If you get graphics artifacts, consider enabling software
rendering with "--enable-software-rendering".
Launching lib\main.dart on AOSP on IA Emulator in debug mode...

Compiler message:
/C:/src/flutter/packages/flutter/lib/src/material/dropdown.dart:1039:69: Error: Type 'WidgetsBindingObserver' not found.
class _DropdownButtonState<T> extends State<DropdownButton<T>> with WidgetsBindingObserver {
                                                                    ^^^^^^^^^^^^^^^^^^^^^^
/C:/src/flutter/packages/flutter/lib/src/widgets/app.dart:711:55: Error: Type 'WidgetsBindingObserver' not found.
class _WidgetsAppState extends State<WidgetsApp> with WidgetsBindingObserver {
                                                      ^^^^^^^^^^^^^^^^^^^^^^
/C:/src/flutter/packages/flutter/lib/src/widgets/app.dart:1205:77: Error: Type 'WidgetsBindingObserver' not found.
class _MediaQueryFromWindowsState extends State<_MediaQueryFromWindow> with WidgetsBindingObserver {
                                                                            ^^^^^^^^^^^^^^^^^^^^^^
/C:/src/flutter/packages/flutter/lib/src/widgets/editable_text.dart:1062:103: Error: Type 'WidgetsBindingObserver' not found.
class EditableTextState extends State<EditableText> with AutomaticKeepAliveClientMixin<EditableText>, WidgetsBindingObserver, TickerProviderStateMixin<EditableText> implements TextInputClient, TextSelectionDelegate {
                                                                                                      ^^^^^^^^^^^^^^^^^^^^^^
/C:/src/flutter/packages/flutter/lib/src/widgets/image.dart:941:45: Error: Type 'WidgetsBindingObserver' not found.
class _ImageState extends State<Image> with WidgetsBindingObserver {
                                            ^^^^^^^^^^^^^^^^^^^^^^
/C:/src/flutter/packages/flutter/lib/src/widgets/semantics_debugger.dart:51:69: Error: Type 'WidgetsBindingObserver' not found.
class _SemanticsDebuggerState extends State<SemanticsDebugger> with WidgetsBindingObserver {
                                                                    ^^^^^^^^^^^^^^^^^^^^^^
/C:/src/flutter/packages/flutter/lib/src/widgets/widget_inspector.dart:2098:10: Error: Type 'WidgetsBindingObserver' not found.
    with WidgetsBindingObserver {
         ^^^^^^^^^^^^^^^^^^^^^^
/C:/src/flutter/packages/flutter/lib/src/widgets/image.dart:941:7: Error: The type 'WidgetsBindingObserver' can't be mixed in.
class _ImageState extends State<Image> with WidgetsBindingObserver {
      ^
/C:/src/flutter/packages/flutter/lib/src/widgets/semantics_debugger.dart:51:7: Error: The type 'WidgetsBindingObserver' can't be mixed in.
class _SemanticsDebuggerState extends State<SemanticsDebugger> with WidgetsBindingObserver {
      ^
/C:/src/flutter/packages/flutter/lib/src/widgets/widget_inspector.dart:2097:7: Error: The type 'WidgetsBindingObserver' can't be mixed in.
class _WidgetInspectorState extends State<WidgetInspector>
      ^
/C:/src/flutter/packages/flutter/lib/src/material/dropdown.dart:1039:7: Error: The type 'WidgetsBindingObserver' can't be mixed in.
class _DropdownButtonState<T> extends State<DropdownButton<T>> with WidgetsBindingObserver {
      ^
/C:/src/flutter/packages/flutter/lib/src/widgets/app.dart:711:7: Error: The type 'WidgetsBindingObserver' can't be mixed in.
class _WidgetsAppState extends State<WidgetsApp> with WidgetsBindingObserver {
      ^
/C:/src/flutter/packages/flutter/lib/src/widgets/app.dart:1205:7: Error: The type 'WidgetsBindingObserver' can't be mixed in.
class _MediaQueryFromWindowsState extends State<_MediaQueryFromWindow> with WidgetsBindingObserver {
      ^
/C:/src/flutter/packages/flutter/lib/src/widgets/editable_text.dart:1062:7: Error: The type 'WidgetsBindingObserver' can't be mixed in.
class EditableTextState extends State<EditableText> with AutomaticKeepAliveClientMixin<EditableText>, WidgetsBindingObserver, TickerProviderStateMixin<EditableText> implements TextInputClient, TextSelectionDelegate {
      ^
lib/main.dart:9:3: Error: Method not found: 'runApp'.
  runApp(new MyApp());
  ^^^^^^
/C:/src/flutter/packages/flutter/lib/src/material/dropdown.dart:1066:39: Error: The getter 'WidgetsBinding' isn't defined for the class '_DropdownButtonState<T>'.
 - '_DropdownButtonState' is from 'package:flutter/src/material/dropdown.dart' ('/C:/src/flutter/packages/flutter/lib/src/material/dropdown.dart').
Try correcting the name to the name of an existing getter, or defining a getter or field named 'WidgetsBinding'.
    final FocusManager focusManager = WidgetsBinding.instance.focusManager;
                                      ^^^^^^^^^^^^^^
/C:/src/flutter/packages/flutter/lib/src/material/dropdown.dart:1073:5: Error: The getter 'WidgetsBinding' isn't defined for the class '_DropdownButtonState<T>'.
 - '_DropdownButtonState' is from 'package:flutter/src/material/dropdown.dart' ('/C:/src/flutter/packages/flutter/lib/src/material/dropdown.dart').
Try correcting the name to the name of an existing getter, or defining a getter or field named 'WidgetsBinding'.
    WidgetsBinding.instance.removeObserver(this);
    ^^^^^^^^^^^^^^
/C:/src/flutter/packages/flutter/lib/src/material/dropdown.dart:1075:5: Error: The getter 'WidgetsBinding' isn't defined for the class '_DropdownButtonState<T>'.
 - '_DropdownButtonState' is from 'package:flutter/src/material/dropdown.dart' ('/C:/src/flutter/packages/flutter/lib/src/material/dropdown.dart').
Try correcting the name to the name of an existing getter, or defining a getter or field named 'WidgetsBinding'.
    WidgetsBinding.instance.focusManager.removeHighlightModeListener(_handleFocusHighlightModeChange);
    ^^^^^^^^^^^^^^
/C:/src/flutter/packages/flutter/lib/src/widgets/app.dart:718:31: Error: The getter 'WidgetsBinding' isn't defined for the class '_WidgetsAppState'.
 - '_WidgetsAppState' is from 'package:flutter/src/widgets/app.dart' ('/C:/src/flutter/packages/flutter/lib/src/widgets/app.dart').
Try correcting the name to the name of an existing getter, or defining a getter or field named 'WidgetsBinding'.
    _locale = _resolveLocales(WidgetsBinding.instance.window.locales, widget.supportedLocales);
                              ^^^^^^^^^^^^^^
/C:/src/flutter/packages/flutter/lib/src/widgets/app.dart:719:5: Error: The getter 'WidgetsBinding' isn't defined for the class '_WidgetsAppState'.
 - '_WidgetsAppState' is from 'package:flutter/src/widgets/app.dart' ('/C:/src/flutter/packages/flutter/lib/src/widgets/app.dart').
Try correcting the name to the name of an existing getter, or defining a getter or field named 'WidgetsBinding'.
    WidgetsBinding.instance.addObserver(this);
    ^^^^^^^^^^^^^^
/C:/src/flutter/packages/flutter/lib/src/widgets/app.dart:731:5: Error: The getter 'WidgetsBinding' isn't defined for the class '_WidgetsAppState'.
 - '_WidgetsAppState' is from 'package:flutter/src/widgets/app.dart' ('/C:/src/flutter/packages/flutter/lib/src/widgets/app.dart').
Try correcting the name to the name of an existing getter, or defining a getter or field named 'WidgetsBinding'.
    WidgetsBinding.instance.removeObserver(this);
    ^^^^^^^^^^^^^^
/C:/src/flutter/packages/flutter/lib/src/widgets/app.dart:1071:23: Error: The getter 'WidgetsBinding' isn't defined for the class '_WidgetsAppState'.
 - '_WidgetsAppState' is from 'package:flutter/src/widgets/app.dart' ('/C:/src/flutter/packages/flutter/lib/src/widgets/app.dart').
Try correcting the name to the name of an existing getter, or defining a getter or field named 'WidgetsBinding'.
        initialRoute: WidgetsBinding.instance.window.defaultRouteName != Navigator.defaultRouteName
                      ^^^^^^^^^^^^^^
/C:/src/flutter/packages/flutter/lib/src/widgets/app.dart:1072:15: Error: The getter 'WidgetsBinding' isn't defined for the class '_WidgetsAppState'.
 - '_WidgetsAppState' is from 'package:flutter/src/widgets/app.dart' ('/C:/src/flutter/packages/flutter/lib/src/widgets/app.dart').
Try correcting the name to the name of an existing getter, or defining a getter or field named 'WidgetsBinding'.
            ? WidgetsBinding.instance.window.defaultRouteName
              ^^^^^^^^^^^^^^
/C:/src/flutter/packages/flutter/lib/src/widgets/app.dart:1073:38: Error: The getter 'WidgetsBinding' isn't defined for the class '_WidgetsAppState'.
 - '_WidgetsAppState' is from 'package:flutter/src/widgets/app.dart' ('/C:/src/flutter/packages/flutter/lib/src/widgets/app.dart').
Try correcting the name to the name of an existing getter, or defining a getter or field named 'WidgetsBinding'.
            : widget.initialRoute ?? WidgetsBinding.instance.window.defaultRouteName,
                                     ^^^^^^^^^^^^^^
/C:/src/flutter/packages/flutter/lib/src/widgets/app.dart:1209:5: Error: The getter 'WidgetsBinding' isn't defined for the class '_MediaQueryFromWindowsState'.
 - '_MediaQueryFromWindowsState' is from 'package:flutter/src/widgets/app.dart' ('/C:/src/flutter/packages/flutter/lib/src/widgets/app.dart').
Try correcting the name to the name of an existing getter, or defining a getter or field named 'WidgetsBinding'.
    WidgetsBinding.instance.addObserver(this);
    ^^^^^^^^^^^^^^
/C:/src/flutter/packages/flutter/lib/src/widgets/app.dart:1254:39: Error: The getter 'WidgetsBinding' isn't defined for the class '_MediaQueryFromWindowsState'.
 - '_MediaQueryFromWindowsState' is from 'package:flutter/src/widgets/app.dart' ('/C:/src/flutter/packages/flutter/lib/src/widgets/app.dart').
Try correcting the name to the name of an existing getter, or defining a getter or field named 'WidgetsBinding'.
      data: MediaQueryData.fromWindow(WidgetsBinding.instance.window),
                                      ^^^^^^^^^^^^^^
/C:/src/flutter/packages/flutter/lib/src/widgets/app.dart:1261:5: Error: The getter 'WidgetsBinding' isn't defined for the class '_MediaQueryFromWindowsState'.
 - '_MediaQueryFromWindowsState' is from 'package:flutter/src/widgets/app.dart' ('/C:/src/flutter/packages/flutter/lib/src/widgets/app.dart').
Try correcting the name to the name of an existing getter, or defining a getter or field named 'WidgetsBinding'.
    WidgetsBinding.instance.removeObserver(this);
    ^^^^^^^^^^^^^^
/C:/src/flutter/packages/flutter/lib/src/widgets/binding.dart:10:45: Error: The argument type 'Type' can't be assigned to the parameter type 'PreferredSizeWidget'.
 - 'Type' is from 'dart:core'.
 - 'PreferredSizeWidget' is from 'package:flutter/src/widgets/preferred_size.dart' ('/C:/src/flutter/packages/flutter/lib/src/widgets/preferred_size.dart').
  return MaterialApp(home: Scaffold(appBar: AppBar ,),);
                                            ^
/C:/src/flutter/packages/flutter/lib/src/widgets/drag_target.dart:633:5: Error: The getter 'WidgetsBinding' isn't defined for the class '_DragAvatar<T>'.
 - '_DragAvatar' is from 'package:flutter/src/widgets/drag_target.dart' ('/C:/src/flutter/packages/flutter/lib/src/widgets/drag_target.dart').
Try correcting the name to the name of an existing getter, or defining a getter or field named 'WidgetsBinding'.
    WidgetsBinding.instance.hitTest(result, globalPosition + feedbackOffset);
    ^^^^^^^^^^^^^^
/C:/src/flutter/packages/flutter/lib/src/widgets/editable_text.dart:1590:32: Error: The getter 'WidgetsBinding' isn't defined for the class 'EditableTextState'.
 - 'EditableTextState' is from 'package:flutter/src/widgets/editable_text.dart' ('/C:/src/flutter/packages/flutter/lib/src/widgets/editable_text.dart').
Try correcting the name to the name of an existing getter, or defining a getter or field named 'WidgetsBinding'.
    if (_lastBottomViewInset < WidgetsBinding.instance.window.viewInsets.bottom) {
                               ^^^^^^^^^^^^^^
/C:/src/flutter/packages/flutter/lib/src/widgets/editable_text.dart:1593:28: Error: The getter 'WidgetsBinding' isn't defined for the class 'EditableTextState'.
 - 'EditableTextState' is from 'package:flutter/src/widgets/editable_text.dart' ('/C:/src/flutter/packages/flutter/lib/src/widgets/editable_text.dart').
Try correcting the name to the name of an existing getter, or defining a getter or field named 'WidgetsBinding'.
    _lastBottomViewInset = WidgetsBinding.instance.window.viewInsets.bottom;
                           ^^^^^^^^^^^^^^
/C:/src/flutter/packages/flutter/lib/src/widgets/editable_text.dart:1712:7: Error: The getter 'WidgetsBinding' isn't defined for the class 'EditableTextState'.
 - 'EditableTextState' is from 'package:flutter/src/widgets/editable_text.dart' ('/C:/src/flutter/packages/flutter/lib/src/widgets/editable_text.dart').
Try correcting the name to the name of an existing getter, or defining a getter or field named 'WidgetsBinding'.
      WidgetsBinding.instance.addObserver(this);
      ^^^^^^^^^^^^^^
/C:/src/flutter/packages/flutter/lib/src/widgets/editable_text.dart:1713:30: Error: The getter 'WidgetsBinding' isn't defined for the class 'EditableTextState'.
 - 'EditableTextState' is from 'package:flutter/src/widgets/editable_text.dart' ('/C:/src/flutter/packages/flutter/lib/src/widgets/editable_text.dart').
Try correcting the name to the name of an existing getter, or defining a getter or field named 'WidgetsBinding'.
      _lastBottomViewInset = WidgetsBinding.instance.window.viewInsets.bottom;
                             ^^^^^^^^^^^^^^
/C:/src/flutter/packages/flutter/lib/src/widgets/editable_text.dart:1720:7: Error: The getter 'WidgetsBinding' isn't defined for the class 'EditableTextState'.
 - 'EditableTextState' is from 'package:flutter/src/widgets/editable_text.dart' ('/C:/src/flutter/packages/flutter/lib/src/widgets/editable_text.dart').
Try correcting the name to the name of an existing getter, or defining a getter or field named 'WidgetsBinding'.
      WidgetsBinding.instance.removeObserver(this);
      ^^^^^^^^^^^^^^
/C:/src/flutter/packages/flutter/lib/src/widgets/focus_manager.dart:1152:39: Error: Getter not found: 'WidgetsBinding'.
  static FocusManager get instance => WidgetsBinding.instance.focusManager;
                                      ^^^^^^^^^^^^^^
/C:/src/flutter/packages/flutter/lib/src/widgets/focus_manager.dart:1210:75: Error: The getter 'WidgetsBinding' isn't defined for the class 'FocusManager'.
 - 'FocusManager' is from 'package:flutter/src/widgets/focus_manager.dart' ('/C:/src/flutter/packages/flutter/lib/src/widgets/focus_manager.dart').
Try correcting the name to the name of an existing getter, or defining a getter or field named 'WidgetsBinding'.
    _lastInteractionWasTouch ??= Platform.isAndroid || Platform.isIOS || !WidgetsBinding.instance.mouseTracker.mouseIsConnected;
                                                                          ^^^^^^^^^^^^^^
/C:/src/flutter/packages/flutter/lib/src/widgets/focus_manager.dart:1433:31: Error: Getter not found: 'WidgetsBinding'.
FocusNode get primaryFocus => WidgetsBinding.instance.focusManager.primaryFocus;
                              ^^^^^^^^^^^^^^
/C:/src/flutter/packages/flutter/lib/src/widgets/focus_manager.dart:1440:10: Error: Getter not found: 'WidgetsBinding'.
  assert(WidgetsBinding.instance != null);
         ^^^^^^^^^^^^^^
/C:/src/flutter/packages/flutter/lib/src/widgets/heroes.dart:803:9: Error: The getter 'WidgetsBinding' isn't defined for the class 'HeroController'.
 - 'HeroController' is from 'package:flutter/src/widgets/heroes.dart' ('/C:/src/flutter/packages/flutter/lib/src/widgets/heroes.dart').
Try correcting the name to the name of an existing getter, or defining a getter or field named 'WidgetsBinding'.
        WidgetsBinding.instance.addPostFrameCallback((Duration value) {
        ^^^^^^^^^^^^^^
/C:/src/flutter/packages/flutter/lib/src/widgets/image.dart:953:5: Error: The getter 'WidgetsBinding' isn't defined for the class '_ImageState'.
 - '_ImageState' is from 'package:flutter/src/widgets/image.dart' ('/C:/src/flutter/packages/flutter/lib/src/widgets/image.dart').
Try correcting the name to the name of an existing getter, or defining a getter or field named 'WidgetsBinding'.
    WidgetsBinding.instance.addObserver(this);
    ^^^^^^^^^^^^^^
/C:/src/flutter/packages/flutter/lib/src/widgets/image.dart:959:5: Error: The getter 'WidgetsBinding' isn't defined for the class '_ImageState'.
 - '_ImageState' is from 'package:flutter/src/widgets/image.dart' ('/C:/src/flutter/packages/flutter/lib/src/widgets/image.dart').
Try correcting the name to the name of an existing getter, or defining a getter or field named 'WidgetsBinding'.
    WidgetsBinding.instance.removeObserver(this);
    ^^^^^^^^^^^^^^
/C:/src/flutter/packages/flutter/lib/src/widgets/image.dart:991:11: Error: Superclass has no method named 'didChangeAccessibilityFeatures'.
    super.didChangeAccessibilityFeatures();
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
/C:/src/flutter/packages/flutter/lib/src/widgets/localizations.dart:522:7: Error: The getter 'WidgetsBinding' isn't defined for the class '_LocalizationsState'.
 - '_LocalizationsState' is from 'package:flutter/src/widgets/localizations.dart' ('/C:/src/flutter/packages/flutter/lib/src/widgets/localizations.dart').
Try correcting the name to the name of an existing getter, or defining a getter or field named 'WidgetsBinding'.
      WidgetsBinding.instance.deferFirstFrameReport();
      ^^^^^^^^^^^^^^
/C:/src/flutter/packages/flutter/lib/src/widgets/localizations.dart:524:9: Error: The getter 'WidgetsBinding' isn't defined for the class '_LocalizationsState'.
 - '_LocalizationsState' is from 'package:flutter/src/widgets/localizations.dart' ('/C:/src/flutter/packages/flutter/lib/src/widgets/localizations.dart').
Try correcting the name to the name of an existing getter, or defining a getter or field named 'WidgetsBinding'.
        WidgetsBinding.instance.allowFirstFrameReport();
        ^^^^^^^^^^^^^^
/C:/src/flutter/packages/flutter/lib/src/widgets/navigator.dart:2325:38: Error: The getter 'WidgetsBinding' isn't defined for the class 'NavigatorState'.
 - 'NavigatorState' is from 'package:flutter/src/widgets/navigator.dart' ('/C:/src/flutter/packages/flutter/lib/src/widgets/navigator.dart').
Try correcting the name to the name of an existing getter, or defining a getter or field named 'WidgetsBinding'.
    _activePointers.toList().forEach(WidgetsBinding.instance.cancelPointer);
                                     ^^^^^^^^^^^^^^
/C:/src/flutter/packages/flutter/lib/src/widgets/scroll_physics.dart:209:30: Error: Getter not found: 'WidgetsBinding'.
    velocity: 1.0 / (0.050 * WidgetsBinding.instance.window.devicePixelRatio), // logical pixels per second
                             ^^^^^^^^^^^^^^
/C:/src/flutter/packages/flutter/lib/src/widgets/scroll_physics.dart:210:21: Error: Getter not found: 'WidgetsBinding'.
    distance: 1.0 / WidgetsBinding.instance.window.devicePixelRatio, // logical pixels
                    ^^^^^^^^^^^^^^
/C:/src/flutter/packages/flutter/lib/src/widgets/semantics_debugger.dart:61:32: Error: The getter 'WidgetsBinding' isn't defined for the class '_SemanticsDebuggerState'.
 - '_SemanticsDebuggerState' is from 'package:flutter/src/widgets/semantics_debugger.dart' ('/C:/src/flutter/packages/flutter/lib/src/widgets/semantics_debugger.dart').
Try correcting the name to the name of an existing getter, or defining a getter or field named 'WidgetsBinding'.
    _client = _SemanticsClient(WidgetsBinding.instance.pipelineOwner)
                               ^^^^^^^^^^^^^^
/C:/src/flutter/packages/flutter/lib/src/widgets/semantics_debugger.dart:63:5: Error: The getter 'WidgetsBinding' isn't defined for the class '_SemanticsDebuggerState'.
 - '_SemanticsDebuggerState' is from 'package:flutter/src/widgets/semantics_debugger.dart' ('/C:/src/flutter/packages/flutter/lib/src/widgets/semantics_debugger.dart').
Try correcting the name to the name of an existing getter, or defining a getter or field named 'WidgetsBinding'.
    WidgetsBinding.instance.addObserver(this);
    ^^^^^^^^^^^^^^
/C:/src/flutter/packages/flutter/lib/src/widgets/semantics_debugger.dart:71:5: Error: The getter 'WidgetsBinding' isn't defined for the class '_SemanticsDebuggerState'.
 - '_SemanticsDebuggerState' is from 'package:flutter/src/widgets/semantics_debugger.dart' ('/C:/src/flutter/packages/flutter/lib/src/widgets/semantics_debugger.dart').
Try correcting the name to the name of an existing getter, or defining a getter or field named 'WidgetsBinding'.
    WidgetsBinding.instance.removeObserver(this);
    ^^^^^^^^^^^^^^
/C:/src/flutter/packages/flutter/lib/src/widgets/semantics_debugger.dart:106:51: Error: The getter 'WidgetsBinding' isn't defined for the class '_SemanticsDebuggerState'.
 - '_SemanticsDebuggerState' is from 'package:flutter/src/widgets/semantics_debugger.dart' ('/C:/src/flutter/packages/flutter/lib/src/widgets/semantics_debugger.dart').
Try correcting the name to the name of an existing getter, or defining a getter or field named 'WidgetsBinding'.
      _lastPointerDownLocation = event.position * WidgetsBinding.instance.window.devicePixelRatio;
                                                  ^^^^^^^^^^^^^^
/C:/src/flutter/packages/flutter/lib/src/widgets/semantics_debugger.dart:158:39: Error: The getter 'WidgetsBinding' isn't defined for the class '_SemanticsDebuggerState'.
 - '_SemanticsDebuggerState' is from 'package:flutter/src/widgets/semantics_debugger.dart' ('/C:/src/flutter/packages/flutter/lib/src/widgets/semantics_debugger.dart').
Try correcting the name to the name of an existing getter, or defining a getter or field named 'WidgetsBinding'.
  PipelineOwner get _pipelineOwner => WidgetsBinding.instance.pipelineOwner;
                                      ^^^^^^^^^^^^^^
/C:/src/flutter/packages/flutter/lib/src/widgets/semantics_debugger.dart:167:9: Error: The getter 'WidgetsBinding' isn't defined for the class '_SemanticsDebuggerState'.
 - '_SemanticsDebuggerState' is from 'package:flutter/src/widgets/semantics_debugger.dart' ('/C:/src/flutter/packages/flutter/lib/src/widgets/semantics_debugger.dart').
Try correcting the name to the name of an existing getter, or defining a getter or field named 'WidgetsBinding'.
        WidgetsBinding.instance.window.devicePixelRatio,
        ^^^^^^^^^^^^^^
/C:/src/flutter/packages/flutter/lib/src/widgets/widget_inspector.dart:904:11: Error: 'WidgetsBinding' isn't a type.
    final WidgetsBinding binding = WidgetsBinding.instance;
          ^^^^^^^^^^^^^^
/C:/src/flutter/packages/flutter/lib/src/widgets/widget_inspector.dart:904:36: Error: The getter 'WidgetsBinding' isn't defined for the class 'WidgetInspectorService'.
 - 'WidgetInspectorService' is from 'package:flutter/src/widgets/widget_inspector.dart' ('/C:/src/flutter/packages/flutter/lib/src/widgets/widget_inspector.dart').
Try correcting the name to the name of an existing getter, or defining a getter or field named 'WidgetsBinding'.
    final WidgetsBinding binding = WidgetsBinding.instance;
                                   ^^^^^^^^^^^^^^
/C:/src/flutter/packages/flutter/lib/src/widgets/widget_inspector.dart:1228:12: Error: The getter 'WidgetsBinding' isn't defined for the class 'WidgetInspectorService'.
 - 'WidgetInspectorService' is from 'package:flutter/src/widgets/widget_inspector.dart' ('/C:/src/flutter/packages/flutter/lib/src/widgets/widget_inspector.dart').
Try correcting the name to the name of an existing getter, or defining a getter or field named 'WidgetsBinding'.
    return WidgetsBinding.instance != null &&
           ^^^^^^^^^^^^^^
/C:/src/flutter/packages/flutter/lib/src/widgets/widget_inspector.dart:1229:12: Error: The getter 'WidgetsBinding' isn't defined for the class 'WidgetInspectorService'.
 - 'WidgetInspectorService' is from 'package:flutter/src/widgets/widget_inspector.dart' ('/C:/src/flutter/packages/flutter/lib/src/widgets/widget_inspector.dart').
Try correcting the name to the name of an existing getter, or defining a getter or field named 'WidgetsBinding'.
           WidgetsBinding.instance.debugDidSendFirstFrameEvent;
           ^^^^^^^^^^^^^^
/C:/src/flutter/packages/flutter/lib/src/widgets/widget_inspector.dart:1592:24: Error: The getter 'WidgetsBinding' isn't defined for the class 'WidgetInspectorService'.
 - 'WidgetInspectorService' is from 'package:flutter/src/widgets/widget_inspector.dart' ('/C:/src/flutter/packages/flutter/lib/src/widgets/widget_inspector.dart').
Try correcting the name to the name of an existing getter, or defining a getter or field named 'WidgetsBinding'.
    return _nodeToJson(WidgetsBinding.instance?.renderViewElement?.toDiagnosticsNode(), _SerializationDelegate(groupName: groupName, service: this));
                       ^^^^^^^^^^^^^^
/C:/src/flutter/packages/flutter/lib/src/widgets/widget_inspector.dart:1603:7: Error: The getter 'WidgetsBinding' isn't defined for the class 'WidgetInspectorService'.
 - 'WidgetInspectorService' is from 'package:flutter/src/widgets/widget_inspector.dart' ('/C:/src/flutter/packages/flutter/lib/src/widgets/widget_inspector.dart').
Try correcting the name to the name of an existing getter, or defining a getter or field named 'WidgetsBinding'.
      WidgetsBinding.instance?.renderViewElement?.toDiagnosticsNode(),
      ^^^^^^^^^^^^^^
/C:/src/flutter/packages/flutter/lib/src/widgets/widget_inspector.dart:2243:41: Error: The getter 'WidgetsBinding' isn't defined for the class '_WidgetInspectorState'.
 - '_WidgetInspectorState' is from 'package:flutter/src/widgets/widget_inspector.dart' ('/C:/src/flutter/packages/flutter/lib/src/widgets/widget_inspector.dart').
Try correcting the name to the name of an existing getter, or defining a getter or field named 'WidgetsBinding'.
    final Rect bounds = (Offset.zero & (WidgetsBinding.instance.window.physicalSize / WidgetsBinding.instance.window.devicePixelRatio)).deflate(_kOffScreenMargin);
                                        ^^^^^^^^^^^^^^
/C:/src/flutter/packages/flutter/lib/src/widgets/widget_inspector.dart:2243:87: Error: The getter 'WidgetsBinding' isn't defined for the class '_WidgetInspectorState'.
 - '_WidgetInspectorState' is from 'package:flutter/src/widgets/widget_inspector.dart' ('/C:/src/flutter/packages/flutter/lib/src/widgets/widget_inspector.dart').
Try correcting the name to the name of an existing getter, or defining a getter or field named 'WidgetsBinding'.
    final Rect bounds = (Offset.zero & (WidgetsBinding.instance.window.physicalSize / WidgetsBinding.instance.window.devicePixelRatio)).deflate(_kOffScreenMargin);
                                                                                      ^^^^^^^^^^^^^^
Target kernel_snapshot failed: Exception: Errors during snapshot creation: null
build failed.

FAILURE: Build failed with an exception.

* Where:
Script 'C:\src\flutter\packages\flutter_tools\gradle\flutter.gradle' line: 780

* What went wrong:
Execution failed for task ':app:compileFlutterBuildDebug'.
> Process 'command 'C:\src\flutter\bin\flutter.bat'' finished with non-zero exit value 1

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.

* Get more help at https://help.gradle.org

BUILD FAILED in 24s
Running Gradle task 'assembleDebug'...
Running Gradle task 'assembleDebug'... Done                        24.9s
Gradle task assembleDebug failed with exit code 1

推荐答案

显然SDK中存在损坏的文件，可以通过 C:\ src \ flutter 重新安装SDK来解决此问题.

Apparently there were corrupt file in SDK, reinstalling the SDK at C:\src\flutter fixed the issue.

这篇关于Fresh Flutter项目有错误:未定义函数"runApp"的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！