Flutter代码报错：setState未定义？-灵析社区

调用setState直接报错，代码提示也没有这个方法，不知道是什么原因  import 'package:flutter/material.dart'; // 导入安卓风格的组件 import 'package:http/http.dart' as http; // 导入http库 class HttpDemo extends StatefulWidget { const HttpDemo({super.key}); @override State createState() => _HttpDemoState(); } class _HttpDemoState extends State { var responseShow = ""; @override Widget build(BuildContext context) { return Scaffold( appBar: AppBar(title: const Text("学习Http库"),), body: Column(children: [ _doGetBtn(), Text("返回的结果：$responseShow") ],), ); } } _doGetBtn(){ return const ElevatedButton(onPressed: _doGet, child: Text("通过Get发送请求")); } // 发送get请求 void _doGet() async{ var uri = Uri.parse("https://api.geekailab.com/uapi/test/test?requestPrams=11"); var response =await http.get(uri); if(response.statusCode == 200){ setState((){ responseShow = response.body; }); } } 网上查询，暂时无果