Question

任何人都可以解释以下内容：我在Flutter中创建了10个小部件，并将它们放在“列表”小部件中。调用小部件的dispose方法时，它是关于它的控制台日志。每个小部件在创建时都会分配一个编号。

情况如下：创建了10个小部件，一切都很好，然后每隔5秒便开始删除它们。编号为1、2、3等的小部件将从列表中删除，但始终将编号为10（最后一个）的小部件称为dispose。

这是日志：

    I/flutter (10173): created 1
    I/flutter (10173): created 2
    I/flutter (10173): created 3
    I/flutter (10173): created 4
    I/flutter (10173): created 5
    I/flutter (10173): created 6
    I/flutter (10173): created 7
    I/flutter (10173): created 8
    I/flutter (10173): created 9
    I/flutter (10173): created 10

    I/flutter (10173): removed 1
    I/flutter (10173): disposed 10

    I/flutter (10173): removed 2
    I/flutter (10173): disposed 10

    I/flutter (10173): removed 3
    I/flutter (10173): disposed 10

    I/flutter (10173): removed 4
    I/flutter (10173): disposed 10

    I/flutter (10173): removed 5
    I/flutter (10173): disposed 10

    I/flutter (10173): removed 6
    I/flutter (10173): disposed 10

    I/flutter (10173): removed 7
    I/flutter (10173): disposed 10

    I/flutter (10173): removed 8
    I/flutter (10173): disposed 10

    I/flutter (10173): removed 9
    I/flutter (10173): disposed 10

    I/flutter (10173): removed 10
    I/flutter (10173): disposed 10

GreenContainer.dart：

    import 'package:flutter/material.dart';



    class GreenContainer extends StatefulWidget {


      String requestId;
      Future timer;

      GreenContainer({this.requestId, this.timer});



      @override
      _GreenContainerState createState() => new _GreenContainerState();

    }

    class _GreenContainerState extends State<GreenContainer> {

      _GreenContainerState() : super();


      @override
      void dispose() async {
        print('disposed ${widget.requestId}');

        super.dispose();
      }


      @override
      void initState() {
        print('created ${widget.requestId}');

        super.initState();
      }

      @override
      Widget build(BuildContext context) {

        return Padding(
          padding: EdgeInsets.only(top: 10.0),
          child: Container(
            height: 100.0,
            color: Colors.green,
          ),
        );
      }

    }

main.dart：

    import 'package:flutter/material.dart';
    import 'package:flutter_app_test/Classs.dart';

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

    class MyApp extends StatelessWidget {
      // This widget is the root of your application.
      @override
      Widget build(BuildContext context) {
        return MaterialApp(
          title: 'Flutter Demo',
          theme: ThemeData(
            primarySwatch: Colors.blue,
          ),
          home: MyHomePage(title: 'Flutter Demo Home Page'),
        );
      }
    }

    class MyHomePage extends StatefulWidget {
      MyHomePage({Key key, this.title}) : super(key: key);

      final String title;

      @override
      _MyHomePageState createState() => _MyHomePageState();
    }


    class _MyHomePageState extends State<MyHomePage> {


      List<GreenContainer> list = [];

      @override
      void initState() {
        print('inited');

        for (int i = 1; i <= 10; i++){
          list.add(
              new GreenContainer(requestId: i.toString(), timer: new Future.delayed(new Duration(milliseconds:  5000 * i ), (){
                  print('removed ' + i.toString());
                  setState(() {
                     list.removeAt(i);
                     print(list);
                  });
                })
              )
          );
        }

        super.initState();
      }

      @override
      Widget build(BuildContext context) {


        return Scaffold(
          appBar: AppBar(
            title: Text(widget.title),
          ),
          body: SingleChildScrollView(
            child: Column(
              children: list,
            ),
          )
        );
      }
    }

似乎是一个问题。请帮助。

从列表中删除小部件时，Flutter总是最后处理

0 个答案: