StatelessWidget类 不需要可变状态的小部件。 StatefulWidget类 具有可变状态( state)的Widget(窗口小部件). import'package:flutter/material.dart';voidmain() { runApp(newApp()); }classApp extends StatelessWidget { @override Widget build(BuildContext context) {returnnewCenter( child:newText('Hello, world!
Widgetbuild(BuildContext context){returnRaisedButton(onPressed:(){setState((){_isPressed=!_isPressed;});},child:Text(_isPressed?'Pressed':'Not Pressed'),);}} 更多关于Widget的信息,你可以参考Flutter Widget介绍。 布局组件:构建灵活的用户界面 在Flutter中,有多种布局组件可供选择,用于在屏幕上排列和...
final Stream<String> dataStream; const MyStatelessWidget({Key key, this.dataStream}) : super(key: key); @override Widget build(BuildContext context) { return StreamBuilder<ConnectionState>( stream: dataStream, builder: (BuildContext context, AsyncSnapshot<ConnectionState> snapshot) { if (snapshot...
@override Widget build(BuildContext context) { return Scaffold( appBar: AppBar( title: Text('监控数据'), ), body: ListView.builder( itemCount: monitoringData.length, itemBuilder: (context, index) { return ListTile( title: Text('网址: ${monitoringData[index]['url']}'), subtitle: Text('...
Widget build(BuildContext context) { return Column( children: ['Apple', 'Orange'].map(Text.new).toList()); } } 「Text.new指Text类的默认构造函数,还可以引用命名构造函数,例如:.map(Text.rich)」。 Related language changes 当实现构造函数的 tear-offs 时,Dart 2.15 借此机会修复了现有的函数指针...
// 正确示例Widgetbuild(BuildContext context){returnRow(children:[RaisedButton(child:Text('Increment'),),Text('Click!'),],);}// 错误示例Widgetbuild(BuildContext context){returnnewRow(children:[newRaisedButton(child:newText('Increment'),),newText('Click!'),],);} ...
StatelessWidget是不可变的,一旦创建就不能更改。它们通常用于表示那些没有状态改变的静态UI元素。例如,Icon、Text、Container等都是无状态的Widget。 class MyStatelessWidget extends StatelessWidget {@overrideWidget build(BuildContext context) {return Container(child: Text('Hello World'),);}} ...
可以直接输入 stl / stf 自动创建 StatelessWidget / StatefluWidget 无状态组件 import 'package:flutter/material.dart';voidmain() =>runApp(MyApp()); class MyAPpp extends StatelessWidget { @override Widget build(BuildContext context) {returnMaterialApp( ...
如图18-16所示的自定义的评分组件RatingStarWidget的基本使用代码如下: //lib/code21/main_data2131.dart //构建五角星评分组件 RatingStarWidgetbuildRatingStarWidget(){ returnRatingStarWidget( //评分回调的数据类型 starType: StarType.iStar, //选中的五角星的高亮颜色 ...
Widgetbuild(BuildContext context){dynamic arguments=ModalRoute.of(context)!.settings.arguments;returnScaffold(appBar:AppBar(title:Text(arguments[1]),),body:Text(arguments.toString()));}} hStatefulWidget import'package:flutter/cupertino.dart';import'package:flutter/material.dart';class$fileName$extends...