java - Stop MediaPlayer service when app goes in Background

Question

I have a media player service that plays music in the background of my app throughout activities like :

public class Music extends Service {
MediaPlayer player;

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

public void onCreate() {
    player = MediaPlayer.create(this, R.raw.music);
    player.setLooping(true);
}

public int onStartCommand(Intent intent, int flags, int startId) {
    player.start();
    return Service.START_NOT_STICKY;
}


public void onDestroy() {
    player.stop();
    player.release();
    stopSelf();
    super.onDestroy();
}

The problem is that when the user changes app or goes to home screen of phone(app goes in the background) the music is still playing.

I have tried to stop it in onStop and onDestroy method but this stops the music when I change activities which is something that I don't want(I want the music to keep playing when user navigates through activities).

Update

I tried with broadcast:

I added

LocalBroadcastManager.getInstance(this).registerReceiver(StateReceiver, new IntentFilter("status"));

in onCreate of music Service and a method to receive events :

private BroadcastReceiver StateReceiver = new BroadcastReceiver() {
    @Override
    public void onReceive(Context context, Intent intent) {
        String status = intent.getStringExtra("status");
        if (parseInt(String.valueOf(status)) == 0) {
            player.stop();
        }else{player.start();}

    }
};

And in Application class I did this:

public class app_class extends Application implements Application.ActivityLifecycleCallbacks {
private static int resumed;
private static int paused;

private static String currentActivity;

@Override
public void onActivityCreated(Activity activity, Bundle savedInstanceState) {
    currentActivity = activity.getClass().getSimpleName();
}
public static String getCurrentActivity() {
    return currentActivity;
}
@Override
public void onActivityStarted(Activity activity) {
}
 @Override
public void onActivityResumed(Activity activity) {
    send_status(1);
}

@Override
public void onActivityPaused(Activity activity) {
    send_status(0);
}  
 private void send_status(int status_counter) {
    Intent intent = new Intent("status");
    intent.putExtra("status", String.valueOf(status_counter));
    LocalBroadcastManager.getInstance(this).sendBroadcast(intent);
}
@Override
public void onActivityStopped(Activity activity) {      

}
@Override
public void onActivitySaveInstanceState(Activity activity, Bundle outState) {

}
@Override
public void onActivityDestroyed(Activity activity) {

}   

But the music wont resume

Answer 1

You need to prepare the player again after stopping it. If you want to stop the playback when your app goes in background, and start the media from the beginning when your app comes into foreground. Just modify your BroadcastReceiver code to this:

private BroadcastReceiver StateReceiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            String status = intent.getStringExtra("status");
            if (parseInt(String.valueOf(status)) == 0) {
                player.stop();
            } else {
                player = MediaPlayer.create(this, R.raw.music);
                player.setLooping(true);
                player.start();
            }

        }
    };

However, if you want to pause the playback and resume it from where you left, then make the following changes: In your Application class, in onActivityDestroyed():

@Override
public void onActivityDestroyed(Activity activity) {
    send_status(2);
}

and in the BroadcastReceiver:

private BroadcastReceiver StateReceiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            String status = intent.getStringExtra("status");
            if (parseInt(String.valueOf(status)) == 0) {
                player.pause();  //When app is in background and not killed, we just want to pause the player and not want to lose the current state.
            } else if (parseInt(String.valueOf(status)) == 1) {
                if (player != null)
                    player.start();  // If the player was created and wasn't stopped, it won't be null, and the playback will be resumed from where we left of.
                else {
                    // If the player was stopped, we need to prepare it once again.
                    player = MediaPlayer.create(this, R.raw.music);
                    player.setLooping(true);
                    player.start();
                }
            } else if(player != null){
                player.stop();
                player.release();
            }

        }
    };

Also, have a look at the MediaPlayer states.