How to update activity UI when i click a button in my notification?

Question

I made a mediaplayer app which plays songs in the background with a service. I have a notification which shows the previous, pause/play and next button.

These buttons work but i would like to change my pause/play buttons state in my Activity when i click the pause/play button in my notification.

So when i for example pause the song in my notification, i want it to also change my button in my activity too the pause drawable.

How can i do this?

Code for the notification in my service which handles the buttons state by passing the playBackStatus (Previous, Pause/Play, Next).

private void NotificationBuilder(PlaybackStatus playbackStatus){
    int notificationAction = R.drawable.ic_action_pause_white;
    PendingIntent play_pause_action = null;

    if (playbackStatus == PlaybackStatus.PLAYING){
        //Pause button created when song is PLAYING
        notificationAction = R.drawable.ic_action_pause_white;
        play_pause_action = playbackAction(1);


    }else if (playbackStatus == PlaybackStatus.PAUSED){
        //Play button created when song is PAUSED
        notificationAction = R.drawable.ic_action_play;
        play_pause_action = playbackAction(0);

    }

EDIT:

play_pause_action is a PendingIntent

notificationBuilder.setShowWhen(false)
            .setStyle(new android.support.v4.media.app.NotificationCompat.MediaStyle().setMediaSession(mMediaSessionCompat.getSessionToken()).setShowActionsInCompactView(0, 1 ,2))
            .setSmallIcon(android.R.drawable.stat_sys_headset).setContentTitle(activeSong.getTitle()).setContentText(activeSong.getArtist())
            .addAction(R.drawable.ic_action_prev_white, null, playbackAction(3))
            .addAction(notificationAction, null, play_pause_action).addAction(R.drawable.ic_action_next_white, null, playbackAction(2))
            .setColor(getResources().getColor(R.color.theme1));

 private PendingIntent playbackAction(int actionNumber) {
        Intent playbackAction = new Intent(this, MediaPlayerService.class);
        switch (actionNumber) {
            case 0:
                // Play
                playbackAction.setAction(Constants.ACTIONS.mACTION_PLAY);
                return PendingIntent.getService(this, actionNumber, playbackAction, 0);
            case 1:
                // Pause
                playbackAction.setAction(Constants.ACTIONS.mACTION_PAUSE);
                return PendingIntent.getService(this, actionNumber, playbackAction, 0);
            case 2:
                // Next track
                playbackAction.setAction(Constants.ACTIONS.mACTION_NEXT);
                return PendingIntent.getService(this, actionNumber, playbackAction, 0);
            case 3:
                // Previous track
                playbackAction.setAction(Constants.ACTIONS.mACTION_PREVIOUS);
                return PendingIntent.getService(this, actionNumber, playbackAction, 0);
            default:
                break;
        }
        return null;
    }

Answer 1

try this :

Button btn=((Button)MainActivity.this.findViewById(R.id.btnPlay));


if (playbackStatus == PlaybackStatus.PLAYING){
        //Pause button created when song is PLAYING
        btn.setImageResource(R.drawable.pause); 
        notificationAction = R.drawable.ic_action_pause_white;
        play_pause_action = playbackAction(1);


}else if (playbackStatus == PlaybackStatus.PAUSED){
      //Play button created when song is PAUSED
       btn.setImageResource(R.drawable.play);
       notificationAction = R.drawable.ic_action_play;
       play_pause_action = playbackAction(0);

}

Answer 2

创建一个界面，然后您就可以处理按钮。在您的界面中添加一个方法，例如示例 handleMybutton (View v){ handle your button what ever you want to do }