flutter - 按下按钮时颤动更新第二个父级
问题描述
我正在开发一个颤振应用程序,我想在按下按钮时更新二级父级的状态。当按下“PressMe”按钮时,我希望 MyHomePage 的状态将 Widget2 的标题字符串保存在它自己的状态中。有人可以帮我解决这个问题吗?该按钮是一个较低级别的小部件,我想将数据向上传递两个级别。谢谢!
//main.dart
import 'package:flutter/material.dart';
import 'Widget1.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: MyHomePage(),
);
}
}
class MyHomePage extends StatefulWidget {
@override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
String title2;
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text("Hello"),
),
body: Center(
child: Widget1(),
),
);
}
}
///////////////////////////////
//Widget1.dart
import 'package:flutter/material.dart';
import 'Widget2.dart';
class Widget1 extends StatefulWidget {
_Widget1State createState() => _Widget1State();
}
class _Widget1State extends State<Widget1> {
@override
Widget build(BuildContext context) {
return Widget2();
}
}
///////////////////////////////
//Widget2.dart
import 'package:flutter/material.dart';
class Widget2 extends StatefulWidget {
final String title = "Hello from Widget2";
_Widget2State createState() => _Widget2State();
}
class _Widget2State extends State<Widget2> {
String title = "Hello from Widget2";
@override
Widget build(BuildContext context) {
return RaisedButton(
onPressed: null,
child: Text(
'PressMe',
style: TextStyle(fontSize: 20)
),
);
}
}
谢谢!
解决方案
从子级更新父级小部件/类的最简单方法是传递function
您在父级中创建的 a,然后在需要更新时从子级调用该函数。但是,如果您需要将它传递给多个孩子,那会变得很混乱。通常在这种情况下,您会希望您的父母成为 aStatefulWidget
并setState
在分配新标题时在您创建的函数中调用。
下一个解决方案是使用InheritedWidget
s 或ChangeNotifier
s。
理想的解决方案是使用某种形式的状态管理,例如Provider
或Bloc
。
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