title: Why images didn't add to the imagescontainer in ListView
body: <p>This is my code
  If I push the button the image is showing after I press the &quot;hot reload&quot; button.</p>
  <p>Question:
  Why can't the images be added to the imagecontainer in <code>ListView</code>?</p>
  <pre class="lang-dart prettyprint-override"><code>    import 'package:flutter/material.dart';
      import 'package:http/http.dart' as http;
      
      void main() {
        runApp(MyApp());
      }
      
      class MyApp extends StatelessWidget {
        @override
        Widget build(BuildContext context) {
          return MaterialApp(
            title: 'Flutter Demo',
            theme: ThemeData(
              primarySwatch: Colors.blue,
            ),
            home: MyHomePage(title: 'Anime Randomizer'),
          );
        }
      }
      
      class MyHomePage extends StatefulWidget {
        MyHomePage({Key key, this.title}) : super(key: key);
        final String title;
      
        @override
        _MyHomePageState createState() =&gt; _MyHomePageState();
      }
      
      class _MyHomePageState extends State&lt;MyHomePage&gt; {
        var urlresult = &quot;https://danbooru.donmai.us/data/original/13/c4/13c4ee9c0f8e305fbe6a4c4efb540ec7.jpg&quot;;
        var filter = &quot;&quot;;
        var error = &quot;&quot;;
        var iterator = 0;
        List&lt;Widget&gt; imagescontainer = [new Container(child: Image.network(&quot;https://danbooru.donmai.us/data/original/13/c4/13c4ee9c0f8e305fbe6a4c4efb540ec7.jpg&quot;, width: 400, height: 650)),];
      
        void fetchAnimeUrl() async {
          var url = Uri.parse('https://danbooru.donmai.us/posts/random?tags=rating%3Asafe${filter != null ? '+'+filter: ''}&amp;format=json');
          final response = await http.get(url);
          if (response.statusCode == 200) {
            var start = response.body.indexOf('file_url');
            var end = response.body.indexOf(',&quot;large_file_url&quot;');
            if(start != -1 || end != -1){
              setState(() {
                iterator++;
                urlresult = response.body.substring(start + 11, end - 1);
                error = imagescontainer.length.toString();
                imagescontainer.add(new Container(child: Image.network(urlresult.toString(), width: 300, height: 620)));
              });
            }
            else{
              setState(() {
                error = &quot;Купить премиум - 25\$&quot;;
              });
            }
          } else {
            throw Exception('Failed to load anime');
          }
        }
      
        @override
        Widget build(BuildContext context) {
          return Scaffold(
            appBar: AppBar(
              title: Text(&quot;Anime randomizer list&quot;),
            ),
            body: Container(
                child: ListView(
                  scrollDirection: Axis.vertical,
                    children: imagescontainer //this variable contain all my images
                ),
            ),
            floatingActionButton: FloatingActionButton(
              onPressed: fetchAnimeUrl,
              tooltip: 'MoreAnime',
              child: Icon(Icons.arrow_circle_down),
            ),
          );
        }
      }
  </code></pre>