flutter3默认空白页

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import 'package:flutter/material.dart';   void main() {   runApp(const MyApp()); }   class MyApp extends StatelessWidget {   const MyApp({super.key});   @override   Widget build(BuildContext context) {     return MaterialApp(       title: '程序名称',       theme: ThemeData(         colorScheme: ColorScheme.fromSeed(seedColor: Colors.deepPurple),         useMaterial3: true,       ),       home: const MyHomePage(title: '顶部标题'),     );   } }   class MyHomePage extends StatefulWidget {   const MyHomePage({super.key, required this.title});     final String title;     @override   State<MyHomePage> createState() => _MyHomePageState(); }   class _MyHomePageState extends State<MyHomePage> {   @override   Widget build(BuildContext context) {     return Scaffold(       appBar: AppBar(         backgroundColor: Theme.of(context).colorScheme.inversePrimary,         title: Text(widget.title),       ),       body: SafeArea(         child: Container(),       ),     );   } }

　　删除了

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int _counter = 0;      void _incrementCounter() {    setState(() {      _counter++;    });  }   floatingActionButton: FloatingActionButton(    onPressed: _incrementCounter,    tooltip: 'Increment',    child: const Icon(Icons.add),  ),

　　删除了

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body: Center(    child: Column(      mainAxisAlignment: MainAxisAlignment.center,      children: <Widget>[        const Text(          'You have pushed the button this many times:',        ),        Text(          '$_counter',          style: Theme.of(context).textTheme.headlineMedium,        ),      ],    ),  ),

　　替换为

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body: SafeArea(   child: Container(), ),

　记录最终例子

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import 'package:flutter/material.dart';   void main() {   runApp(const GoWaterMyApp()); }   class GoWaterMyApp extends StatelessWidget {   const GoWaterMyApp({super.key});   @override   Widget build(BuildContext context) {     return MaterialApp(       title: '程序名称',       theme: ThemeData(         colorScheme: ColorScheme.fromSeed(seedColor: Colors.lightBlue),         useMaterial3: true,       ),       home: const MyHomePage(title: '顶部标题'),     );   } }   class MyHomePage extends StatefulWidget {   const MyHomePage({super.key, required this.title});     final String title;     @override   State<MyHomePage> createState() => _MyHomePageState(); }   class _MyHomePageState extends State<MyHomePage> {   @override   Widget build(BuildContext context) {     return Scaffold(       appBar: AppBar(         backgroundColor: Theme.of(context).colorScheme.inversePrimary,         title: Text(widget.title),       ),       body: SafeArea(         child: Container(),       ),     );   } }