Error: The getter 'length' was called on null - flutter

Question

Error says:
NoSuchMethodError: The getter 'length' was called on null
It is a basic flutter music player App.
main.dart
import 'package:flute_music_player/flute_music_player.dart';
void main() => runApp(MyApp());
class MyApp extends StatefulWidget {
#override
_MyAppState createState() => _MyAppState();
}
class _MyAppState extends State<MyApp> {
List<Song> _songs;
#override
void initState() {
// TODO: implement initState
super.initState();
initPlayer();
}
void initPlayer() async{
var songs = await MusicFinder.allSongs();
songs=new List.from(songs);
setState(() {
_songs = songs;
});
}
#override
Widget build(BuildContext context) {
Widget home(){
new Scaffold(
appBar: new AppBar(title: new Text("Music App"),
),
body: new ListView.builder(
itemCount: _songs.length,
itemBuilder: (context,int index){
return new ListTile(
leading: new CircleAvatar(
child: new Text(_songs[index].title[0]),
),
title: new Text(_songs[index].title),
);
}),
);
}
return new MaterialApp(
home: home(),
);
}
}
pubspec.yaml
name: music_player
description: A new Flutter application.
version: 1.0.0+1
environment:
sdk: ">=2.1.0 <3.0.0"
dependencies:
flutter:
sdk: flutter
cupertino_icons: ^0.1.2
flute_music_player:
dev_dependencies:
flutter_test:
sdk: flutter
flutter:
uses-material-design: true
It should show the list of musics as result but gives an unexpected error.I am running on android.Plz help me out.
It should show the list of musics as result but gives an unexpected error.I am running on android.Plz help me out.

Answer 1

Change itemCount: _songs.length to itemCount: _songs?.length ?? 0 - it helps to avoid exception

Answer 2

Since you're performing an async operation, that would take certain amount of time so when your app first builds, the songs array is null. Try to start with an empty array instead of a null array: List<Song> _songs = []; then, when the async operation is completed the setState will make the widget to rebuild and show the array with data.