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javaandroidandroid-mediaplayer

Android android.media.PlayerBase.PlaybackDetectionCallBack NullPointerException

My app crash only in vivo phones, and the error log is this:

java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String android.content.Context.getOpPackageName()' on a null object reference at android.media.PlayerBase.PlaybackDetectionCallBack(PlayerBase.java:348) at android.media.PlayerBase.baseStop(PlayerBase.java:229) at android.media.MediaPlayer$2.onCompletion(MediaPlayer.java:3578) at android.media.MediaPlayer$EventHandler.handleMessage(MediaPlayer.java:3351) at android.os.Handler.dispatchMessage(Handler.java:106) at android.os.Looper.loop(Looper.java:192) at android.app.ActivityThread.main(ActivityThread.java:6671) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:818)

I believe it is about MediaPlayer which I use to play BGM in my app.

But I can't find out how this happens since the error stack didn't retrieve to my code.

Here is all my code about play BGM.

public void playBgm(final int resId, boolean restartIfSame) {
    if(resId == currentBgmRes && !restartIfSame) {
        if(!bgmPlayer.isPlaying()) {
            bgmPlayer.start();
        }
        return;
    }
    if(bgmPlayer.isPlaying()) {
        bgmPlayer.stop();
    }
    _playBgm(resId);
}

private void _playBgm(int resId) {
    bgmPlayer.release();
    bgmPlayer = MediaPlayer.create(this, resId);
    bgmPlayer.setLooping(true);
    currentBgmRes = resId;
    bgmPlayer.start();
}

The two functions are inside class AppDelegate extends Application, so this should be the application instance.

It doesn't always crash. Since the phone causing the problem is some far-away user's, I can't get the phone in several days. So I'm not sure in what situation it will happen, but it should not happen in any situation.

Solution

  • I figured out the problem.

    My MediaPlayer variable has an initial value new MediaPlayer().

    When the Activity playing the BGM calls onPause(), I call MediaPlayer.pause().

    But calling pause() to a new MediaPlayer() seems to cause crash in some devices, while OK in other devices.

    I change the initial value to null, and do the null check whenever I use the object. The crash never happen again.