Android MediaPlayer OnCompletion NullPointerException

Question

这是我的第一个问题。它在media.release（）行中给出了NullPointerException。确切的输出是NullPointerException（@ ProgressDetailRecyclerViewAdapter $ 5：onCompletion：308）{main}

 public void play(String fileURL) {

    try {
        mediaPlayer = new MediaPlayer();
        mediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC);
        mediaPlayer.setDataSource(fileURL);
        mediaPlayer.prepare();
        mediaPlayer.start();
        mediaPlayer.setOnCompletionListener(new MediaPlayer.OnCompletionListener() {
            @Override
            public void onCompletion(MediaPlayer mp) {
                mediaPlayer.release(); //line 308
                mediaPlayer = null;
            }
        });
    } catch (Exception e) {
        e.printStackTrace();
    }
}

Answer 1

试试这个

mediaPlayer.setOnCompletionListener(new MediaPlayer.OnCompletionListener() {
            @Override
            public void onCompletion(MediaPlayer mp) {
                mp.release(); //line 308
                mp= null;
            }
        });

Answer 2

传递给onCompletion方法的变量名为mp，而不是mediaPlayer。您的mediaPlayer变量可能已被初始化，从而导致错误。将代码更改为：

@Override
public void onCompletion(MediaPlayer mp) {
    mp.release(); //line 308
    mp = null;
}

Answer 3

 @Override
            public void onCompletion(MediaPlayer **mp**) {
                **mediaPlayer**.release(); //line 308
                mediaPlayer = null;
            }

在此方法中使用正确的对象mp而不是mediaPlayer