android – Flutter：刷卡后默认标签栏控制器不保持状态

我正在写一个有颤动的应用程序,有4个标签视图,有点像股票Android手机应用程序或时钟应用程序.其中一个视图散列浮动操作按钮,按下该按钮将在列表中添加一些文本.但是,当我滚动到其他视图之一并返回时,所有文本都消失了.有没有办法解决这个问题？

这是我的代码：

import 'package:Flutter/material.dart';
import 'Screens/Dashboard.dart';
import 'Screens/CreateQuestionnaire.dart';
import 'Screens/AccountScreen.dart';

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

class MyApp extends StatefulWidget {
  @override
 createState() => new MyAppState();
}

class MyAppState extends State<MyApp> {
  final primaryColour = const Color(0xFF5CA1CA);
  final secondaryColour = const Color(0xFFC36B42);
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      home: new DefaultTabController(
        length: 4,
        child: new Scaffold(
          appBar: new AppBar(
            actions: <Widget>[
              new IconButton(icon: new Icon(Icons.account_circle),
              onpressed: (){
                Navigator.push(context, new MaterialPageRoute(builder: (context) => new AccountScreen()));
              }),
            ],
            bottom: new TabBar(
              tabs: <Widget>[
                new Tab(icon: new Icon(Icons.home)),
                new Tab(icon: new Icon(Icons.contacts)),
                new Tab(icon: new Icon(Icons.description)),
                new Tab(icon: new Icon(Icons.settings))
              ],
            ),
            title: new Text("NLPro Questionnaire"),
          ),
          body: new TabBarView(
            children: <Widget>[
              new Dashboard(),
              new CreateQuestionnaire(),
              new Text("Surveys"),
              new Text("Settings")
            ],
          ),
        ),
      ),
      theme:new ThemeData(
        primaryColor: primaryColour,
        accentColor: secondaryColour,
      ),
    );
  }
}

enter image description here

解决方法:

您需要在有状态窗口小部件上使用AutomaticKeepAliveClientMixin并实现名为wantKeepAlive的覆盖方法

class MyApp extends StatefulWidget {
@override
createState() => new MyAppState();
}

将AutomaticKeepAliveClientMixin与您的类扩展状态和ov一起使用

class MyAppState extends State<MyApp> with AutomaticKeepAliveClientMixin<MyApp>{

//your existing code.....

@override
bool get wantKeepAlive => true;   //by default it will be null, change it to true.

//your existing code......

}

在将wantKeepAlive设置为true时,initState方法将在创建时仅运行一次.