重新启动时颤动应用程序在热重新加载后不显示主页它可以工作

如何解决重新启动时颤动应用程序在热重新加载后不显示主页它可以工作

我是 Flutter 应用程序开发的初学者。我正在尝试使用 for 循环从 api 中获取超过 10 个页面，并且 addall 结果在列表中。为此，我创建了 future 函数和 statefulwidget 这是我的代码

    import 'dart:convert';

    import 'package:MovieAPi/infopage.dart';
    import 'package:cached_network_image/cached_network_image.dart';
    import 'package:Flutter/material.dart';
    import 'package:http/http.dart' as http;

    void main() {
      runApp(MyApp());
    }

    List data = [];
    Future<void> _getMovies() async {
      for (var i = 1; i < 10; i++) {
        var url =
            "https://api.themoviedb.org/3/trending/movie/week?api_key=1dce78a9836cf6fbc01190431d9443fe&page=$i";
        http.Response response = await http.get(url);
        var JsonBody = json.decode(response.body);
        data.addAll(JsonBody['results']);
      }
    }

    class MyApp extends StatelessWidget {
      // This widget is the root of your application.
      @override
      Widget build(BuildContext context) {
        return MaterialApp(
          debugShowCheckedModeBanner: false,theme: ThemeData(
            primarySwatch: Colors.blue,textTheme: TextTheme(
              title: TextStyle(
                fontSize: 22,fontWeight: FontWeight.bold,),subtitle: TextStyle(fontSize: 18,fontWeight: FontWeight.w700),visualDensity: VisualDensity.adaptivePlatformDensity,home: MovieTile(),);
      }
    }

    class MovieTile extends StatefulWidget {
      @override
      _MovieTileState createState() => _MovieTileState();
    }

    class _MovieTileState extends State<MovieTile> {
      void initState() {
        super.initState();
        setState(() {
          _getMovies();
        });
      }

      @override
      Widget build(BuildContext context) {
        return Scaffold(
            appBar: AppBar(
              title: Text("Movies",style: Theme.of(context).textTheme.title),backgroundColor: Colors.white,bottomOpacity: 0.0,shadowColor: Colors.white,automaticallyImplyLeading: false,body: ListView.builder(
              itemCount: data.length,itemBuilder: (context,index) {
                String image = data[index]['poster_path'];
                String title = data[index]['title'];
                String release_date = data[index]['overview'];
                String id = data[index]['id'].toString();
                String Vote = data[index]['Vote_average'].toString();
                return GestureDetector(
                  onTap: () {
                    return Navigator.push(context,MaterialPageRoute(builder: (context) => InfoMovie(id)));
                  },child: Padding(
                    padding:
                        const EdgeInsets.symmetric(vertical: 8.0,horizontal: 10),child: Container(
                      width: MediaQuery.of(context).size.width,height: 500.0,decoration: Boxdecoration(
                        borderRadius: BorderRadius.circular(20),image: decorationImage(
                          image: CachednetworkImageProvider(
                            "https://image.tmdb.org/t/p/original$image",fit: BoxFit.cover,BoxShadow: [
                          BoxShadow(
                            offset: Offset(1,9),blurRadius: 10,color: Colors.black26,)
                        ],child: Stack(
                        children: [
                          Container(
                            decoration: Boxdecoration(
                              color: Colors.black26,borderRadius: BorderRadius.circular(20),Positioned(
                            bottom: 0,child: Container(
                              decoration: Boxdecoration(
                                color: Colors.black.withOpacity(0.5),borderRadius: BorderRadius.only(
                                  bottomLeft: Radius.circular(20),bottomright: Radius.circular(20),padding: EdgeInsets.all(20),width: MediaQuery.of(context).size.width * 0.95,child: Column(
                                crossAxisAlignment: CrossAxisAlignment.start,children: [
                                  Text(
                                    title,style: Theme.of(context)
                                        .textTheme
                                        .title
                                        .copyWith(color: Colors.white),SizedBox(height: 5),Text(
                                    release_date,style: Theme.of(context)
                                        .textTheme
                                        .subtitle
                                        .copyWith(
                                            color: Colors.white.withOpacity(0.9)),textAlign: TextAlign.left,maxLines: 3,overflow: TextOverflow.ellipsis,softWrap: true,],Positioned(
                            top: 20,left: 10,child: Container(
                              height: 50,width: 50,decoration: Boxdecoration(
                                  shape: BoxShape.circle,border: Border.all(
                                      color: Colors.white.withOpacity(0.6),width: 1)),child: Center(
                                child: Container(
                                  height: 40,width: 40,decoration: Boxdecoration(
                                    shape: BoxShape.circle,color: Colors.white,child: Center(
                                    child: Text(
                                      Vote,style: TextStyle(
                                        fontWeight: FontWeight.bold,fontSize: 18,);
              },));
      }
    }

当我打开应用程序时什么都不显示 like this 只有空白屏幕 当我热重载然后显示结果时 here

解决方法

首先，setState 中不需要 initState。其次，由于 ListView.builder 是页面正文的根元素，您无法直接看到 data 内容，因为它在应用启动时为空 data = []。

为了解决这个问题，你最好尝试这样的事情

return Scaffold(
  body: data.length > 0 ? ListView.builder(
    // ...
  ) : Center(
    child: CircularProgressIndicator(),),)

此外，最好将 List data 变量和 _getMovies 函数放在 _MovieTileState 中

class _MovieTileState extends State<MovieTile> {
  List data;
  void initState() {
    super.initState();

    data = [];
    _getMovies();
  }

  Future<void> _getMovies() async {
    for (var i = 1; i < 10; i++) {
      var url = "https://api.themoviedb.org/3/trending/movie/week?api_key=1dce78a9836cf6fbc01190431d9443fe&page=$i";
      http.Response response = await http.get(url);
      var JsonBody = json.decode(response.body);
      setState(() {
        data.addAll(JsonBody['results']);
      });
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          // ...
        ),body: data.length > 0 ? ListView.builder(
          // ...
        ) : Center(
          child: CircularProgressIndicator(),);
  }
}