在另一个带有另一个小部件的列表视图中回调列表视图？

Question

我正在尝试使用列表视图调用体内的列表视图，该列表视图什么也不显示“空” 如何通过在列表视图内调用另一个列表视图来解决此问题？很难解释。

body: new ListView(
  children: <Widget>[
    HomePageListView(),
  ],
),

Answer 1

以下是嵌套的ListView示例。请注意收缩包装：真和容器高度
您可以将内部部件重构为另一个小部件

原始代码段

Expanded(
              child: ListView.builder(
                  shrinkWrap: true,
                  itemCount: litems.length,
                  itemBuilder: (BuildContext ctxt, int Index) {
                    return ExpansionTile(
                      title: Text(litems[Index]),
                      children: <Widget>[
                        Text(litems[Index]),
                        Container(
                          height : 300,
                          child: ListView.builder(
                              shrinkWrap: true,
                              scrollDirection: Axis.horizontal,
                              itemCount: litems1.length,
                              itemBuilder: (BuildContext ctxt, int Index) {
                                return Text(litems1[Index]);
                              }),
                        )
                      ],
                    );
                  }),
            )

将代码段重构为小部件

 Expanded(
              child: ListView.builder(
                  shrinkWrap: true,
                  itemCount: litems.length,
                  itemBuilder: (BuildContext ctxt, int Index) {
                    return ExpansionTile(
                      title: Text(litems[Index]),
                      children: <Widget>[
                        Text(litems[Index]),
                        new innerOneWidget(litems1: litems1)
                      ],
                    );
                  }),
            ),

...
class innerOneWidget extends StatelessWidget {
  const innerOneWidget({
    Key key,
    @required this.litems1,
  }) : super(key: key);

  final List<String> litems1;

  @override
  Widget build(BuildContext context) {
    return Container(
      height : 300,
      child: ListView.builder(
          shrinkWrap: true,
          scrollDirection: Axis.horizontal,
          itemCount: litems1.length,
          itemBuilder: (BuildContext ctxt, int Index) {
            return Text(litems1[Index]);
          }),
    );
  }
}

完整代码

import 'package:flutter/material.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(
        // This is the theme of your application.
        //
        // Try running your application with "flutter run". You'll see the
        // application has a blue toolbar. Then, without quitting the app, try
        // changing the primarySwatch below to Colors.green and then invoke
        // "hot reload" (press "r" in the console where you ran "flutter run",
        // or simply save your changes to "hot reload" in a Flutter IDE).
        // Notice that the counter didn't reset back to zero; the application
        // is not restarted.
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

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

  // This widget is the home page of your application. It is stateful, meaning
  // that it has a State object (defined below) that contains fields that affect
  // how it looks.

  // This class is the configuration for the state. It holds the values (in this
  // case the title) provided by the parent (in this case the App widget) and
  // used by the build method of the State. Fields in a Widget subclass are
  // always marked "final".

  final String title;

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

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

  void _incrementCounter() {
    setState(() {
      // This call to setState tells the Flutter framework that something has
      // changed in this State, which causes it to rerun the build method below
      // so that the display can reflect the updated values. If we changed
      // _counter without calling setState(), then the build method would not be
      // called again, and so nothing would appear to happen.
      _counter++;
    });
  }

  List<String> litems = ['1', '2', '3', '4'];
  List<String> litems1 = [' hi ', ' this ', ' is ', ' long ', ' long ',' long ',' long ',' long ',' long ',' long ',' long ',' long ',' long ',' long ',' long '];

  @override
  Widget build(BuildContext context) {
    // This method is rerun every time setState is called, for instance as done
    // by the _incrementCounter method above.
    //
    // The Flutter framework has been optimized to make rerunning build methods
    // fast, so that you can just rebuild anything that needs updating rather
    // than having to individually change instances of widgets.
    return Scaffold(
      appBar: AppBar(
        // Here we take the value from the MyHomePage object that was created by
        // the App.build method, and use it to set our appbar title.
        title: Text(widget.title),
      ),
      body: Center(
        // Center is a layout widget. It takes a single child and positions it
        // in the middle of the parent.
        child: Column(
          // Column is also layout widget. It takes a list of children and
          // arranges them vertically. By default, it sizes itself to fit its
          // children horizontally, and tries to be as tall as its parent.
          //
          // Invoke "debug painting" (press "p" in the console, choose the
          // "Toggle Debug Paint" action from the Flutter Inspector in Android
          // Studio, or the "Toggle Debug Paint" command in Visual Studio Code)
          // to see the wireframe for each widget.
          //
          // Column has various properties to control how it sizes itself and
          // how it positions its children. Here we use mainAxisAlignment to
          // center the children vertically; the main axis here is the vertical
          // axis because Columns are vertical (the cross axis would be
          // horizontal).
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Expanded(
              child: ListView.builder(
                  shrinkWrap: true,
                  itemCount: litems.length,
                  itemBuilder: (BuildContext ctxt, int Index) {
                    return ExpansionTile(
                      title: Text(litems[Index]),
                      children: <Widget>[
                        Text(litems[Index]),
                        new innerOneWidget(litems1: litems1)
                      ],
                    );
                  }),
            ),
            Text(
              'You have pushed the button this many times:',
            ),
            Text(
              '$_counter',
              style: Theme.of(context).textTheme.display1,
            ),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: Icon(Icons.add),
      ), // This trailing comma makes auto-formatting nicer for build methods.
    );
  }
}

class innerOneWidget extends StatelessWidget {
  const innerOneWidget({
    Key key,
    @required this.litems1,
  }) : super(key: key);

  final List<String> litems1;

  @override
  Widget build(BuildContext context) {
    return Container(
      height : 300,
      child: ListView.builder(
          shrinkWrap: true,
          scrollDirection: Axis.horizontal,
          itemCount: litems1.length,
          itemBuilder: (BuildContext ctxt, int Index) {
            return Text(litems1[Index]);
          }),
    );
  }
}

演示图片，外部ListView垂直滚动，内部ListView水平滚动

Answer 2

只是真正的rinkleWrap

shrinkWrap : true

Answer 3

在HomePageListView上设置

  

shrinkWrap：是

到列表视图

Answer 4

在第二个列表上使用波纹管属性

shrinkWrap: true,
physics: NeverScrollableScrollPhysics()