Flutter:如何确保异步函数中变量的正确初始化？

import 'package:flutter/material.dart';

class MyWidget extends StatelessWidget {
  Future<String> fetchData() async {
    // 模拟异步操作，比如从网络获取数据
    await Future.delayed(Duration(seconds: 2));
    return 'Hello World';
  }

  @override
  Widget build(BuildContext context) {
    return FutureBuilder<String>(
      future: fetchData(),
      builder: (BuildContext context, AsyncSnapshot<String> snapshot) {
        if (snapshot.connectionState == ConnectionState.waiting) {
          // 如果异步操作还在进行中，显示加载中的UI
          return CircularProgressIndicator();
        } else if (snapshot.hasError) {
          // 如果异步操作出错，显示错误信息
          return Text('Error: ${snapshot.error}');
        } else {
          // 如果异步操作成功完成，显示数据
          return Text('Data: ${snapshot.data}');
        }
      },
    );
  }
}