Question

我创建了这个应用程序，其中该应用程序会生成一个随机符号列表，但是每个第5个元素都有相同的符号，并且该符号随后会最终打印出来。一切正常，直到我到达最后一页，我想创建一个按钮来刷新整个应用程序，并且符号再次变得随机。我尝试使用该按钮并将其链接以再次转到首页，但是图标保持不变。

这是我的代码，如果我很杂乱，我很抱歉：- https://dartpad.dev/725f4a6f4bd97c5a4a9e43b2af9159d6

https://pastebin.com/k4ZTWiSE



import 'package:flutter/material.dart';
import "dart:math";

var list = ['❤', '✌', '?', '?', '?', '?', '❄', '?'];
List<dynamic> notes = new List();

final _random2 = new Random();
var element2 = list[_random2.nextInt(list.length)];
var x = element2;

void main() {
  runApp(MyApp()
  );
}

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

class _MyAppState extends State<MyApp> {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  int index = 0;

  List<dynamic> myText = [
    'All symbols are random',
    'but all number divisible by 5 have same symbols',
    'last page will show you the common symbol',
  ];

  void changeText() {
    setState(() {
      index++;
      if (index == myText.length) {
        index = 0;

        Navigator.push(
          context,
          MaterialPageRoute(builder: (context) => SecondRoute()),
        );
      }
      for (int i = 0; i < 100; i++) {
        if ((i + 1) % 5 == 0) {
          notes.add('${i + 1}.) $x');
        } else {
          final _random = new Random();
          var element = list[_random.nextInt(list.length)];

          notes.add('${i + 1}.) $element');
        }
      }
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('random'),
      ),
      body: SingleChildScrollView(
        child: Container(
          width: MediaQuery.of(context).size.width,
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.center,
            children: [
              Container(
                padding: EdgeInsets.all(50),
                child: Text(
                  myText[index],
                ),
              ),
            ],
          ),
        ),
      ),
      floatingActionButton: FloatingActionButton(
        child: Icon(Icons.navigate_next),
        onPressed: changeText,
      ),
    );
  }
}

class SecondRoute extends StatefulWidget {
  @override
  _SecondRouteState createState() => _SecondRouteState();
}

class _SecondRouteState extends State<SecondRoute> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          title: Text("random"),
        ),
        body: Container(
          color: Colors.white10,
          padding: EdgeInsets.all(16.0),
          child: HomePage(notes),
        ),
        floatingActionButton: FloatingActionButton(
          child: Icon(Icons.navigate_next),
          onPressed: () => Navigator.push(
            context,
            MaterialPageRoute(builder: (context) => SecondRoute2()),
          ),
        ));
  }
}

class HomePage extends StatefulWidget {
  final List<dynamic> notes;

  HomePage(this.notes);

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

class _HomePageState extends State<HomePage> {
  @override
  Widget build(BuildContext context) {
    return ListView.builder(
      itemCount: widget.notes.length,
      itemBuilder: (context, pos) {
        return Padding(
          padding: EdgeInsets.only(bottom: 16.0),
          child: Card(
            color: Colors.white,
            child: Padding(
              padding: EdgeInsets.symmetric(vertical: 24.0, horizontal: 16.0),
              child: Text(
                widget.notes[pos],
                style: TextStyle(
                  fontSize: 18.0,
                  height: 1.6,
                ),
              ),
            ),
          ),
        );
      },
    );
  }
}

class SecondRoute2 extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          title: Text("List"),
        ),
        body: Container(
          color: Colors.white10,
          padding: EdgeInsets.all(16.0),
          child: Text('$x'),
        ),
        floatingActionButton: FloatingActionButton(
            child: Icon(Icons.refresh),
            onPressed: () => MyApp));
  }
}

Answer 1

您重复的元素是这个，在文件作用域设置：

var element2 = list[_random2.nextInt(list.length)];

在您的changeText函数中，只需像这样重新分配它：

  void changeText() {
    setState(() {
      // not needed after all! final _random = new Random(); // add this
      element2 = list[_random2.nextInt(list.length)]; // ... and this
      x = element2; // and this
      index++;
      if (index == myText.length) {
        index = 0;
        notes=[]; // update: add this

您不必重新启动应用程序-只需重新分配即可。注意：您有element2和x似乎总是具有相同的值。您可能应该只选择一个变量并使用它，而不要让两个具有相同的值。

如何重新启动整个应用程序？

1 个答案: