Flutter异步方法返回小部件不起作用

FutureBuilder(
  future: yourAsyncMethod(),
  builder: (BuildContext context, AsyncSnapshot snapshot) {
    if (snapshot.connectionState == ConnectionState.waiting) {
      return CircularProgressIndicator(); // 加载中的小部件
    } else if (snapshot.hasError) {
      return Text('Error: ${snapshot.error}'); // 错误信息的小部件
    } else {
      return Text('Result: ${snapshot.data}'); // 显示异步结果的小部件
    }
  },
)

class YourWidget extends StatefulWidget {
  @override
  _YourWidgetState createState() => _YourWidgetState();
}

class _YourWidgetState extends State<YourWidget> {
  String result;

  @override
  void initState() {
    super.initState();
    yourAsyncMethod().then((value) {
      setState(() {
        result = value; // 更新小部件的状态
      });
    });
  }

  @override
  Widget build(BuildContext context) {
    return Text('Result: $result'); // 使用更新后的状态构建小部件
  }
}

StreamBuilder(
  stream: yourAsyncMethod().asStream(),
  builder: (BuildContext context, AsyncSnapshot snapshot) {
    if (snapshot.connectionState == ConnectionState.waiting) {
      return CircularProgressIndicator(); // 加载中的小部件
    } else if (snapshot.hasError) {
      return Text('Error: ${snapshot.error}'); // 错误信息的小部件
    } else {
      return Text('Result: ${snapshot.data}'); // 显示异步结果的小部件
    }
  },
)