Shows a foreground notification for an Android service. Tapping the notification will display the app as if it was tapped in application launcher

showForegroundNotification.java

//In a service
public void showNotification(){
        Intent notificationIntent = new Intent(getApplicationContext(),MainActivity.class);
        notificationIntent.setAction(Intent.ACTION_MAIN);
        notificationIntent.addCategory(Intent.CATEGORY_LAUNCHER);
        notificationIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);

        PendingIntent contentIntent = PendingIntent.getActivity(
                getApplicationContext(),
                0,
                notificationIntent,
                PendingIntent.FLAG_UPDATE_CURRENT);
        Notification notification  = new Notification.Builder(getApplicationContext())
                .setContentTitle(getString(R.string.app_name))
                .setContentText(getString(R.string.running_background))
                .setSmallIcon(R.mipmap.ic_launcher)
                .setWhen(System.currentTimeMillis())
                .setContentIntent(contentIntent)
                .setAutoCancel(true)
                .build();
        startForeground(NOTIF_ID,notification);
}

//In activity
    @Override
    protected void onResume(){
        super.onResume();
        //Notification should disappear when activty goes to foreground
        NotificationManager manager =
                (NotificationManager)getApplicationContext().getSystemService(Context.NOTIFICATION_SERVICE);
        manager.cancel(MonitorService.NOTIF_ID);
    }

    @Override
    protected void onPause() {
        super.onPause();
        //Notification should appear when activity goes to background
        monitorService.showNotification();
    }

Super useful, thanks!