从外部方法传递异常错误以显示在小部件树中

import 'package:flutter/material.dart';

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

class _MyWidgetState extends State<MyWidget> {
  String errorMessage = '';

  void fetchData() {
    try {
      // 调用外部方法，可能抛出异常
      // ...
    } catch (e) {
      setState(() {
        // 将异常信息保存到errorMessage变量中
        errorMessage = e.toString();
      });
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('异常显示示例'),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            // 显示异常信息的小部件
            Text(
              errorMessage,
              style: TextStyle(color: Colors.red),
            ),
            RaisedButton(
              onPressed: fetchData,
              child: Text('获取数据'),
            ),
          ],
        ),
      ),
    );
  }
}