Flutter 点击展开和关闭

import 'package:flutter/material.dart';
import 'expansion_tile_demo.dart';
main(){
  runApp(MyApp());
}
class MyApp extends StatelessWidget {

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData.dark(),
      home: ExpansionTileDemo()
    );
  }
}

import 'package:flutter/material.dart';
class ExpansionTileDemo extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('Expansion Tile Demo')),
      body: Center(
        child: ExpansionTile(
          title: Text('Expansion Tile '),
          // 放开始的组件
          leading: Icon(Icons.ac_unit),

          // 设置点开后的背景颜色
          backgroundColor: Colors.white24,
          // 设置展开显示的内容
          children: <Widget>[
            ListTile(
              title: Text('List title'),
              subtitle: Text('Subtitle'),
            )
          ],
          // 第一次显示打开的状态
          //initiallyExpanded: true,
        ),
      ),
    );
  }
}