音频播放器包"the method 'loop' was called on null"错误

Question

我试图通过单击相同的按钮打开和关闭声音，但我得到一个"方法'loop'被调用为null。"错误。我不能理解它的逻辑，因为我是一个业余爱好者。如果你对我有任何建议，我已经准备好倾听学习扑动。

class _MyHomePageState extends State<MyHomePage> {
AudioPlayer player;
AudioCache cache;
bool playing = false;
@override
Widget build(BuildContext context) {
return Scaffold(
body: Center(
child: IconButton(
iconSize: 50,
icon: Icon(
Icons.play_arrow,
color: Colors.pink,
),
onPressed: () {
if (playing = true) {
cache.loop("drum13.wav", volume: 3);
} else {
player.pause();
}
},
),
),
);
}
}

Answer 1

你应该调用构造函数。

AudioCache cache = AudioCache();
AudioPlayer player = AudioPlayer();