@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
    if (keyCode == KeyEvent.KEYCODE_HEADSETHOOK) {
        if (!medService.getAction().equals(Constants.PLAY)) {
            medService.setAction(Constants.PLAY);
            startService(medService);
            mPlayPause.setChecked(true);
        }

        else if (!medService.getAction().equals(Constants.PAUSE)) {
            medService.setAction(Constants.PAUSE);
            startService(medService);
            mPlayPause.setChecked(false);
        }
    }
    return super.onKeyDown(keyCode, event);
}