flutter 错误 : the getter 'AudioPlayerState' isn't defined for the class '_HomePageState'

Question

我已经导入了 audioplayer.dart 但它仍然向我显示错误:getter 'AudioPlayerState' 没有为类 '_HomePageState' 定义

import 'package:audioplayers/audioplayers.dart';
_audioPlayer.onPlayerStateChanged.listen((event) {
  if (event == AudioPlayerState.PLAYING) {
    _isPlaying = true;
  } else {
    _isPlaying = false;
  }
  setState(() {});
});

Answer 1

  if (event == PlayerState.PLAYING) {