Flutter:类型'Future<dynamic>‘不是类型'Widget’的子类型

import 'package:flutter/material.dart';

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

class _MyWidgetState extends State<MyWidget> {
  Future<dynamic> fetchData() async {
    // 模拟异步操作
    await Future.delayed(Duration(seconds: 2));
    return 'Hello, World!';
  }

  @override
  Widget build(BuildContext context) {
    return FutureBuilder<dynamic>(
      future: fetchData(),
      builder: (BuildContext context, AsyncSnapshot<dynamic> snapshot) {
        if (snapshot.connectionState == ConnectionState.waiting) {
          // 显示加载中的UI
          return CircularProgressIndicator();
        } else if (snapshot.hasError) {
          // 显示错误信息的UI
          return Text('Error: ${snapshot.error}');
        } else {
          // 显示异步操作结果的UI
          return Text('Result: ${snapshot.data}');
        }
      },
    );
  }
}