未找到材质本地化 - MyApp 小部件要求由本地化小部件祖先提供材质本地化 - No MaterialLocalizations found - MyApp widgets require MaterialLocalizations to be provided by a Localizations widget ancestor 小贝子编程网

我只是想创建一个带有按钮的应用程序，当按下按钮时会显示一条警报消息。

但它给了我这个错误(下面提到)。

我通过参考此视频编写了此代码。

我正在使用adb connect在实时安卓手机上运行该应用程序

请帮忙..！

法典

import 'package:flutter/material.dart';
void main(){
runApp(MyApp());
}
class MyApp extends StatelessWidget{
@override
Widget build(BuildContext context) {
return MaterialApp(
title: "Test",
home: Scaffold(
appBar: AppBar(title: Text("Test")),
body: Container(
child: Center(
child: RaisedButton(
color: Colors.redAccent,
textColor: Colors.white,
onPressed: (){testAlert(context);},
child: Text("PressMe"),
),
),
),
),
);
}
void testAlert(BuildContext context){
var alert = AlertDialog(
title: Text("Test"),
content: Text("Done..!"),
);
showDialog(
context: context,
builder: (BuildContext context){
return alert;
}
);
}
}

这是我编写的代码。我还尝试将testAlert()函数的内容直接插入onPressed中，但不起作用。

错误

Performing hot reload...
Syncing files to device ZUK Z2131...
Reloaded 0 of 419 libraries in 1,929ms.
I/flutter (18652): ══╡ EXCEPTION CAUGHT BY GESTURE ╞═══════════════════════════════════════════════════════════════════
I/flutter (18652): The following assertion was thrown while handling a gesture:
I/flutter (18652): No MaterialLocalizations found.
I/flutter (18652): MyApp widgets require MaterialLocalizations to be provided by a Localizations widget ancestor.
I/flutter (18652): Localizations are used to generate many different messages, labels,and abbreviations which are used
I/flutter (18652): by the material library. 
I/flutter (18652): To introduce a MaterialLocalizations, either use a  MaterialApp at the root of your application to
I/flutter (18652): include them automatically, or add a Localization widget with a MaterialLocalizations delegate.
I/flutter (18652): The specific widget that could not find a MaterialLocalizations ancestor was:
I/flutter (18652):   MyApp
I/flutter (18652): The ancestors of this widget were:
I/flutter (18652):   [root]
I/flutter (18652): 
I/flutter (18652): When the exception was thrown, this was the stack:
I/flutter (18652): #0      debugCheckHasMaterialLocalizations.<anonymous closure> (package:flutter/src/material/debug.dart:124:7)
I/flutter (18652): #1      debugCheckHasMaterialLocalizations (package:flutter/src/material/debug.dart:127:4)
I/flutter (18652): #2      showDialog (package:flutter/src/material/dialog.dart:635:10)
I/flutter (18652): #3      MyApp.testAlert (package:flutter_app/main.dart:33:5)
I/flutter (18652): #4      MyApp.build.<anonymous closure> (package:flutter_app/main.dart:19:29)
I/flutter (18652): #5      _InkResponseState._handleTap (package:flutter/src/material/ink_well.dart:507:14)
I/flutter (18652): #6      _InkResponseState.build.<anonymous closure> (package:flutter/src/material/ink_well.dart:562:30)
I/flutter (18652): #7      GestureRecognizer.invokeCallback (package:flutter/src/gestures/recognizer.dart:102:24)
I/flutter (18652): #8      TapGestureRecognizer._checkUp (package:flutter/src/gestures/tap.dart:242:9)
I/flutter (18652): #9      TapGestureRecognizer.handlePrimaryPointer (package:flutter/src/gestures/tap.dart:175:7)
I/flutter (18652): #10     PrimaryPointerGestureRecognizer.handleEvent (package:flutter/src/gestures/recognizer.dart:315:9)
I/flutter (18652): #11     PointerRouter._dispatch (package:flutter/src/gestures/pointer_router.dart:73:12)
I/flutter (18652): #12     PointerRouter.route (package:flutter/src/gestures/pointer_router.dart:101:11)
I/flutter (18652): #13     _WidgetsFlutterBinding&BindingBase&GestureBinding.handleEvent (package:flutter/src/gestures/binding.dart:180:19)
I/flutter (18652): #14     _WidgetsFlutterBinding&BindingBase&GestureBinding.dispatchEvent (package:flutter/src/gestures/binding.dart:158:22)
I/flutter (18652): #15     _WidgetsFlutterBinding&BindingBase&GestureBinding._handlePointerEvent (package:flutter/src/gestures/binding.dart:138:7)
I/flutter (18652): #16     _WidgetsFlutterBinding&BindingBase&GestureBinding._flushPointerEventQueue (package:flutter/src/gestures/binding.dart:101:7)
I/flutter (18652): #17     _WidgetsFlutterBinding&BindingBase&GestureBinding._handlePointerDataPacket (package:flutter/src/gestures/binding.dart:85:7)
I/flutter (18652): #18     _invoke1 (dart:ui/hooks.dart:168:13)
I/flutter (18652): #19     _dispatchPointerDataPacket (dart:ui/hooks.dart:122:5)
I/flutter (18652): 
I/flutter (18652): Handler: onTap
I/flutter (18652): Recognizer:
I/flutter (18652):   TapGestureRecognizer#d5d82(debugOwner: GestureDetector, state: possible, won arena, finalPosition:
I/flutter (18652):   Offset(220.2, 406.1), sent tap down)
I/flutter (18652): ════════════════════════════════════════════════════════════════════════════════════════════════════
W/ActivityThread(18652): handleWindowVisibility: no activity for token android.os.BinderProxy@59b4e8d
I/ViewRootImpl(18652): CPU Rendering VSync enable = true

这是因为您传递给showDialog方法的上下文是小部件树中还没有MaterialLocalizations小部件的context，因此MaterialLocalizations小部件由MaterialApp小部件隐式添加。

要解决此问题，请尝试以下操作：

import 'package:flutter/material.dart';
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
title: "Test",
home: TestPage(),
);
}
}
class TestPage extends StatelessWidget {
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(title: Text("Test")),
body: Container(
child: Center(
child: RaisedButton(
color: Colors.redAccent,
textColor: Colors.white,
onPressed: () {
testAlert(context);
},
child: Text("PressMe"),
),
),
),
);
}
void testAlert(BuildContext context) {
var alert = AlertDialog(
title: Text("Test"),
content: Text("Done..!"),
);
showDialog(
context: context,
builder: (BuildContext context) {
return alert;
});
}
}

在我的情况下，一个简单的解决方法就是将 MaterialApp 小部件移动到 main() 方法。

main() {
runApp(MaterialApp(home: App()));
}

当您切换到GlobalMaterialLocalizations委托不支持的语言时，也会发生这种情况。这是一个很难理解的消息，因为它说你应该在树的顶部有MaterialApp，但这可能已经存在。

就我而言，我本地化的语言(英国威尔士语 -cy-GB)不会自动满足。我必须为样板字符串编写自己的委托，并将其添加到应用根目录的本地化列表中。

白俄罗斯代表的代码在这里。我对其进行了调整以迎合威尔士语。它包含日期格式信息，以及材料设计认为您可能需要的大约七十个常用短语，例如"全选"，"页面的"等。

如果您需要创建一个涵盖全局材料本地化中未列出的语言的委托，那么一旦您创建了委托，查看您的代码库，在树顶部附近的某个地方，您将有一行类似

MaterialApp(
localizationsDelegates: [
GlobalMaterialLocalizations.delegate,
GlobalWidgetsLocalizations.delegate,
GlobalCupertinoLocalizations.delegate,
],
supportedLocales: [
const Locale('en', ''), // English, no country code
const Locale('he', ''), // Hebrew, no country code
const Locale.fromSubtags(languageCode: 'zh')
],
// ...
)

只需将CyMaterialLocalizations.delegate(或任何您称呼的新语言代理)添加到localizationsDelegates列表中即可。

我对RaisedButton内部的showTimePicker有同样的问题，

我重组为：

runApp 
|__MaterialApp
|__ StatefulWidget/StatelessWidget
|__SafeArea
|__Scaffold
|__ RaisedButton
|__ showTimePicker

以下是示例工作解决方案：

import 'package:flutter/material.dart';
import 'package:flutter_localizations/flutter_localizations.dart';
void main() {
runApp(
MaterialApp(
debugShowCheckedModeBanner: false,
localizationsDelegates: [
GlobalMaterialLocalizations.delegate,
GlobalWidgetsLocalizations.delegate,
GlobalCupertinoLocalizations.delegate,
],
supportedLocales: [
const Locale('en', 'US'), 
],
home: Sample(),
),
);
}
class Sample extends StatefulWidget {
@override
_SampleState createState() => _SampleState();
}
class _SampleState extends State<Sample> {
@override
Widget build(BuildContext context) {
return SafeArea(
child: Scaffold(
body: Center(
child: RaisedButton(
child: Text('Time Picker'),
onPressed: () {
showTimePicker(
context: context,
initialTime: TimeOfDay(hour: 10, minute: 47),
builder: (BuildContext context, Widget child) {
return MediaQuery(
data: MediaQuery.of(context)
.copyWith(alwaysUse24HourFormat: true),
child: child,
);
},
);
},
),
),
),
);
}
}

将localizationsDelegates和supportedLocales添加到MaterialApp为我解决了问题

localizationsDelegates: [
GlobalMaterialLocalizations.delegate,
GlobalWidgetsLocalizations.delegate,
GlobalCupertinoLocalizations.delegate,
],
supportedLocales: [
Locale('en', 'US'),
],

另一种方法是用Builder包装调用showDialog的最内部小部件。在这种情况下，最内部的小部件是TextButton(请注意，我用TextButton替换了已弃用的RaisedButton)。

import 'package:flutter/material.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
home: Scaffold(
appBar: AppBar(title: Text("Test")),
body: Container(
child: Builder(
builder: (context) {
return TextButton(
child: const Text('Show'),
onPressed: () {
showDialog(
context: context,
builder: (_) => AlertDialog(
title: Text("Test"),
content: Text("Done..!"),
),
);
},
);
},
),
),
),
);
}
}

我遇到了同样的问题，我需要在其中显示 dailog

initState();

我像这样解决，

Future.delayed(Duration.zero, () {
showGameOverDailog(context);
});

就我而言，当我在 StatefulWidget 中插入此记录时，它发生了：

const MyApp({Key? key}) : super(key: key);

localizationsDelegates: [
MonthYearPickerLocalizations.delegate,
],

我正在使用MonthYearPicker软件包，我必须将其添加到我的MaterialApp小部件中

。

我遇到了这个问题 2 天，2 天后小技巧对我有用。

我只是保留supportedLocales: const [Locale('en', 'IN')]并删除其他人。

另一种方法是删除supportedLocales: const [Locale('en', 'IN')]也对我有用。

构建方法应返回MaterialApp 而不是 Scaffold。在您的材料应用程序的家中，您可以拥有脚手架

Widget build(BuildContext context) {
return MaterialApp(
home: Scaffold(),   //or your Page with Scaffold
);
}

解决此问题的最简单方法是将页面重命名为主页在此处输入图像描述

然后返回 Home 类中的基架小部件

在此处输入图像描述

未找到材质本地化 - MyApp 小部件要求由本地化小部件祖先提供材质本地化

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