Flutter 扩展磁贴尾随图标在与一个磁贴交互时更新列表中的所有内容.如何只更改展开图块的图标

要仅更改展开的磁贴的图标，可以使用以下方法:

创建一个Map:

Map<int, bool> state = {};

并相应地在您的ExpansionTile中使用它来判断它是否被选中，如果值是true或false:

 List.generate(6, (index) {
          return ExpansionTile(
            title: Text('Item $index'),
            trailing: state[index] ?? false
                ? Icon(Icons.arrow_drop_up)
                : Icon(Icons.arrow_drop_down),
            onExpansionChanged: (value) {
              setState(() {
                state[index] = value;
              });
            },
            children: [
              Container(
                height: 100,
                color: Colors.red,
              ),
            ],
          );
        }),

完整的可运行示例:

import 'package:flutter/material.dart';

const Color darkBlue = Color.fromARGB(255, 18, 32, 47);

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData.dark().copyWith(
        scaffoldBackgroundColor: darkBlue,
      ),
      debugShowCheckedModeBanner: false,
      home: Scaffold(
        body: Center(
          child: MyWidget(),
        ),
      ),
    );
  }
}

class MyWidget extends StatefulWidget {
  @override
  State<MyWidget> createState() => _MyWidgetState();
}

class _MyWidgetState extends State<MyWidget> {
  Map<int, bool> state = {};

  bool isExpanded = false;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Flutter Demo Home Page'),
      ),
      body: Column(
        children:
            // generate 6 ExpansionTiles
            List.generate(6, (index) {
          return ExpansionTile(
            title: Text('Item $index'),
            trailing: state[index] ?? false
                ? Icon(Icons.arrow_drop_up)
                : Icon(Icons.arrow_drop_down),
            onExpansionChanged: (value) {
              setState(() {
                state[index] = value;
              });
            },
            children: [
              Container(
                height: 100,
                color: Colors.red,
              ),
            ],
          );
        }),
      ),
    );
  }
}