Question

我创建了SimpleDialog和由数据列表生成的许多SimpleDialogOptions，是否可以检测到SimpleDialogOption的索引？如果没有，我试图在对话框中使用列表，但它只显示一个空对话框，那么如何在对话框中使用列表呢？

Answer 1

我可以想到两种方式 1.Map和indexOf方法 2.简单的循环

结果：

守则：

import 'dart:async';

import 'package:flutter/material.dart';

void main() => runApp(
      new MaterialApp(
        home: new MyApp(),
      ),
    );

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

class _MyAppState extends State<MyApp> {
  int index = 0;
  List<String> myList = new List();

  @override
  void initState() {
    super.initState();
    /*Adding elements to data list*/
    for (int i = 0; i < 5; i++) myList.add("Title $i");
  }

  /*First Way*/

  Future<Null> _showList1() async {
    int selected = await showDialog<int>(
        context: context,
        builder: (BuildContext context) {
          return new SimpleDialog(
            title: const Text('Select'),
            children: myList.map((value) {
              return new SimpleDialogOption(
                onPressed: () {
                  Navigator.pop(context, myList.indexOf(value));//here passing the index to be return on item selection
                },
                child: new Text(value),//item value
              );
            }).toList(),
          );
        });
    setState(() {
      index = selected;
    });
  }

  /*Second Way*/

  Future<Null> _showList2() async {
    int selected = await showDialog<int>(
        context: context,
        builder: (BuildContext context) {
          return new SimpleDialog(
            title: const Text('Select'),
            children: getOption(),
          );
        });
    setState(() {
      index = selected;
    });
  }

  List<Widget> getOption() {
    List<Widget> options = new List();
    for (int i = 0; i < myList.length; i++)
      options.add(new SimpleDialogOption(
        onPressed: () {
          Navigator.pop(context, i);//here passing the index to be return on item selection
        },
        child: new Text(myList[i]),//item value
      ));
    return options;
  }

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      appBar: new AppBar(
        title: new Text("NonStopIO"),
      ),
      body: new Center(
        child: new Column(
          children: <Widget>[
            new Padding(
              padding: const EdgeInsets.all(100.0),
            ),
            new Text(
              "Selected Index : $index",
              style: new TextStyle(fontSize: 30.0),
            ),
            new Padding(
              padding: const EdgeInsets.all(18.0),
            ),
            new Row(
              mainAxisAlignment: MainAxisAlignment.spaceAround,
              children: <Widget>[
                new RaisedButton(
                  onPressed: () async {
                    _showList1();
                  },
                  child: new Text("Show List [ First Way ] "),
                ),
                new RaisedButton(
                  onPressed: () async {
                    _showList2();
                  },
                  child: new Text("Show List [ Second Way ] "),
                )
              ],
            ),
          ],
        ),
      ),
    );
  }
}

SimpleDialog中的项目

1 个答案: