Не удается запустить музыкальный проигрыватель виджета Android

Question

У меня есть свой музыкальный проигрыватель, и я хочу взаимодействовать с виджетом проигрывателя на экране блокировки, а также с уведомлением. Я создал для моего сеансового класса.

Ex: Моя идея такова: когда я нажимаю кнопку btnPlay в моем приложении, я вижу, что она называется public void onPlay() function в MediaPlayerService.java через:

MainActivity.java

Intent intent = new Intent(getApplicationContext(),MediaPlayerService.class);
intent.setAction(MediaPlayerService.ACTION_PAUSE);
startService(intent);

MediaPlayerService.java

@Override
public void onPlay() {
    super.onPlay();
    buildNotifacation(generateAction(android.R.drawable.ic_media_pause,"PAUSE",ACTION_PAUSE));

    MainActivity activity = MainActivity.instance;
    activity.performClick();

}

Когда я удалил: MainActivity activity = MainActivity.instance; activity.performClick(); -> он работал нормально. Но когда я добавил его, он не мог работать.

Я хочу управлять музыкальным проигрывателем (Play, Stop, Rewind ...) в моем приложении через MainActivity и MediaPlayerService. Но основная цель - через виджет.

Вот мой код:

MainActivity:

public class MainActivity extends AppCompatActivity implements TimePickerDialog.OnTimeSetListener {

    static MainActivity instance;

    private static final int SECOND_ACTIVITY_RESULT_CODE = 0;

    // Used to load the 'native-lib' library on application startup.
    static {
        System.loadLibrary("native-lib");
    }

          btnPlay.setOnClickListener(new View.OnClickListener()

    {
        @Override
        public void onClick (View v){

        if (mediaPlayer.isPlaying()) {
            //if song is running --> pause --> change icon to play
            mediaPlayer.pause();
            btnPlay.setImageResource(R.drawable.ic_player_play);

                    **Intent intent = new Intent(getApplicationContext(), MediaPlayerService.class);
            intent.setAction(MediaPlayerService.ACTION_PAUSE);
            startService(intent);**

        } else {
            //if song is stop --> start --> change icon to pause
            mediaPlayer.start();
            btnPlay.setImageResource(R.drawable.ic_player_pause);

                    **Intent intent = new Intent(getApplicationContext(), MediaPlayerService.class);
            intent.setAction(MediaPlayerService.ACTION_PLAY);
            startService(intent);**


        }
        setTimeTotal();
        UpdateTimeSong();

    }
    });


    public void performClick() {
        btnPlay.post(new Runnable() {
            @Override
            public void run() {
                btnPlay.performClick();
            }
        });
    }
}

MediaPlayerService.java:

public class MediaPlayerService extends Service {

    private MediaSession mSession;
    public static final String ACTION_PLAY = "action_play";
    public static final String ACTION_PAUSE = "action_pause";
    public static final String ACTION_REWIND = "action_rewind";
    public static final String ACTION_FAST_FORWARD = "action_fast_forward";
    public static final String ACTION_NEXT = "action_next";
    public static final String ACTION_PREVIOUS = "action_previous";
    public static final String ACTION_STOP = "action_stop";


    private MediaPlayer mMediaPlayer;
    private MediaSessionManager mManager;
    private android.media.session.MediaController mController;

    MainActivity mActivity = new MainActivity();

    ArrayList<Song> arraySong;

    protected PendingIntent getPendingSelfIntent(Context context, String action) {
        Intent intent = new Intent(context, getClass());
        intent.setAction(action);
        return PendingIntent.getBroadcast(context, 0, intent, 0);
    }

    @Nullable
    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }

    @Override
    public boolean onUnbind(Intent intent) {
        mSession.release();
        return super.onUnbind(intent);
    }

    private void handleIndent(Intent intent) {
        if (intent == null || intent.getAction() == null) {
            return;
        }
        String action = intent.getAction();
        if (action.equalsIgnoreCase(ACTION_PLAY)) {
            mController.getTransportControls().play();
        } else if (action.equalsIgnoreCase(ACTION_PAUSE)) {
            mController.getTransportControls().pause();
        } else if (action.equalsIgnoreCase(ACTION_FAST_FORWARD)) {
            mController.getTransportControls().fastForward();
        } else if (action.equalsIgnoreCase(ACTION_REWIND)) {
            mController.getTransportControls().rewind();
        } else if (action.equalsIgnoreCase(ACTION_PREVIOUS)) {
            mController.getTransportControls().skipToPrevious();
        } else if (action.equalsIgnoreCase(ACTION_NEXT)) {
            mController.getTransportControls().skipToNext();
        } else if (action.equalsIgnoreCase(ACTION_STOP)) {
            mController.getTransportControls().stop();
        }
    }

    private Notification.Action generateAction(int icon, String title, String intentAction) {
        Intent intent = new Intent(getApplicationContext(), MediaPlayerService.class);
        intent.setAction(intentAction);

        PendingIntent pendingIntent = PendingIntent.getService(getApplicationContext(), 1, intent, 0);
        return new Notification.Action.Builder(icon, title, pendingIntent).build();
    }

    private void buildNotifacation(Notification.Action action) {
        Notification.MediaStyle style = new Notification.MediaStyle();
        Intent intent = new Intent(getApplicationContext(), MediaPlayerService.class);
        intent.setAction(ACTION_STOP);
        PendingIntent pendingIntent = PendingIntent.getService(getApplicationContext(), 1, intent, 0);

        Notification.Builder builder = new Notification.Builder(this)
                .setSmallIcon(R.mipmap.ic_launcher)
                .setContentTitle("Lock Screen Media Example")
                .setContentText("Artis Name")
                .setDeleteIntent(pendingIntent)
                .setStyle(style);

        builder.addAction(generateAction(android.R.drawable.ic_media_previous, "Previous", ACTION_PREVIOUS));
        builder.addAction(generateAction(android.R.drawable.ic_media_rew, "Rewind", ACTION_REWIND));
        builder.addAction(action);
        builder.addAction(generateAction(android.R.drawable.ic_media_ff, "Fast Forward", ACTION_FAST_FORWARD));
        builder.addAction(generateAction(android.R.drawable.ic_media_next, "Next", ACTION_NEXT));
        style.setShowActionsInCompactView(0, 1, 2, 3, 4);

        NotificationManager notificationManager =
                (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
        notificationManager.notify(1, builder.build());
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        if (mManager == null) {
            initMediaSession();
        }
        handleIndent(intent);
        return super.onStartCommand(intent, flags, startId);
    }

    private void initMediaSession() {
        mMediaPlayer = new MediaPlayer();
        mSession = new MediaSession(getApplicationContext(), "example player session");
        mController = new android.media.session.MediaController(getApplicationContext(), mSession.getSessionToken());

        mSession.setCallback(new MediaSession.Callback() {

            @Override
            public void onPlay() {
                super.onPlay();
                **
                buildNotifacation(generateAction(android.R.drawable.ic_media_pause, "PAUSE", ACTION_PAUSE));
                mMediaPlayer = MediaPlayer.create(MediaPlayerService.this, arraySong.get(0).getFile());
                MainActivity activity = MainActivity.instance;
                activity.performClick();**

            }

            @Override
            public void onPause() {
                super.onPause();
                buildNotifacation(generateAction(android.R.drawable.ic_media_play, "PAUSE", ACTION_PLAY));
                mMediaPlayer.stop();
            }
        }
    }
}

Когда я нажимал btnPlay на приложении или кнопку «Воспроизвести» на виджете, приложение останавливалось.

Итак, мой вопрос: я использую правильный метод для виджета Music Player? Если да, может ли кто-нибудь помочь мне решить эту проблему?