我是 Flutter/Dart 的新手,所以可能没有使用所有正确的关键字,但我遇到了一个问题,我在类 'FirstPageState' extends State 下得到了一条红线.这会阻止我调试应用程序,所以我来到这里希望能得到解决方案!
这是我的“FirstPage.dart”代码
import 'dart:async';
import 'package:flutter/material.dart';
import 'package:http/http.dart' as http;
String _FirstPageText = 'Exchange Rates';
class First extends StatefulWidget {
// This widget is the root of your application.
@override
FirstPageState createState() => new FirstPageState();
Widget build(BuildContext context) {
return new MaterialApp(
home: new Scaffold(
appBar: new AppBar(
title: new Text(_FirstPageText),
centerTitle: true,
backgroundColor: Colors.black,
),
body: new FeedWidget(),
),
);
}
}
class FirstPageState extends State<First> {
Future<String> getData() async {
var response = await http.get(
'https://jsonplaceholder.typicode.com/posts'
);
}
}
谢谢你:)
最佳答案
如果您阅读“红线”,您会看到一个错误,可能是 State
为 an abstract class期望 one or more methods to be defined :
Instance, getter, and setter methods can be abstract, defining an interface but leaving its implementation up to other classes
在这种情况下,我相信State
expects the build
method .你可能想看看 documentation behind StatefulWidget
,它描述了什么是必要的:
class YellowBird extends StatefulWidget { const YellowBird({ Key key }) : super(key: key); @override _YellowBirdState createState() => new _YellowBirdState(); } class _YellowBirdState extends State<YellowBird> { @override Widget build(BuildContext context) { return new Container(color: const Color(0xFFFFE306)); } }
关于class - flutter 类不工作,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/50650411/