How to fix service performance?

Question

Java

Hello, I have a fragment where music and service are played, so that, when minimized, the music continues to play. I click on the play, it crashes out of the application, and if I remove if (mediaPlayer == null) it starts working, only the pause still stops working, who knows what the problem is?
service:

public class AudioPlaybackService extends Service implements MediaPlayer.OnPreparedListener, MediaPlayer.OnCompletionListener
{
public class AudioPlaybackService extends Service implements MediaPlayer.OnPreparedListener, MediaPlayer.OnCompletionListener
{
    MediaPlayer mediaPlayer;
    public static final String EXTRA_AUDIO_URL = "audio_url";
    String url;
    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {

        if (mediaPlayer == null){
            this.url = intent.getStringExtra(EXTRA_AUDIO_URL);
            try {
                mediaPlayer.reset();
                mediaPlayer.setDataSource(url);
                mediaPlayer.prepareAsync();
                mediaPlayer.setOnPreparedListener(new MediaPlayer.OnPreparedListener() {
                    @Override
                    public void onPrepared(MediaPlayer mediaPlayer) {
                        mediaPlayer.start();
                    }
                });
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        else if(mediaPlayer.isPlaying()){
            mediaPlayer.pause();
        } else {
            mediaPlayer.start();
        }
        return START_STICKY;

    }
    @Override
    public void onCreate()
    {
        super.onCreate();
        mediaPlayer =  new MediaPlayer();
        mediaPlayer.setOnPreparedListener(this);
        mediaPlayer.setOnCompletionListener(this);
    }

    @Override
    public void onCompletion(MediaPlayer mp)
    {
        // called when song has ended
    }

    @Override
    public void onPrepared(MediaPlayer mp)
    {
        mediaPlayer.start();
    }

    @Override
    public IBinder onBind(Intent arg0)
    {
        // TODO Auto-generated method stub
        return null;
    }
}

Fragment(кнопка паузы и старта):
playPause.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
               serviceIntent.putExtra(AudioPlaybackService.EXTRA_AUDIO_URL, "http://stream3.radiostyle.ru:8003/radioacca");
                getActivity().startService(serviceIntent);

Answer 1

if (mediaPlayer == null){
            this.url = intent.getStringExtra(EXTRA_AUDIO_URL);
            try {
                mediaPlayer.reset();

There is, no doubt, a mistake here. You check that the player is null, and then you start calling methods on it. If you add onCreate here, where you initialize the player, it becomes clear that the check is not needed.
Why do you put OnPreparedListener twice - it's not clear.
isPlaying() may return false a few seconds after start():

It may take some time before the state is updated in calls to isPlaying(), and it can be a number of seconds in the case of streamed content.

link .