Is it possible to check if a notification is visible or canceled?

If you're app has a minimum API >= 23 can use this method to get active notification:

NotificationManager mNotificationManager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
StatusBarNotification[] notifications = mNotificationManager.getActiveNotifications();
for (StatusBarNotification notification : notifications) {
  if (notification.getId() == 100) {
    // Do something.
  }
}

This is how I solved it:

    private boolean isNotificationVisible() {
    Intent notificationIntent = new Intent(context, MainActivity.class);
    PendingIntent test = PendingIntent.getActivity(context, MY_ID, notificationIntent, PendingIntent.FLAG_NO_CREATE);
    return test != null;
}

This is how I generate the notification:

    /**
 * Issues a notification to inform the user that server has sent a message.
 */
private void generateNotification(String text) {

    int icon = R.drawable.notifiaction_icon;
    long when = System.currentTimeMillis();
    NotificationManager notificationManager = (NotificationManager) context.getSystemService(Context.NOTIFICATION_SERVICE);
    Notification notification = new Notification(icon, text, when);
    String title = context.getString(R.string.app_name);
    Intent notificationIntent = new Intent(context, MainActivity.class);

    // set intent so it does not start a new activity
    //notificationIntent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP | Intent.FLAG_ACTIVITY_SINGLE_TOP);
    PendingIntent intent = PendingIntent.getActivity(context, MY_ID, notificationIntent, 0);
    notification.setLatestEventInfo(context, title, text, intent);

    notification.flags |= Notification.FLAG_AUTO_CANCEL; //PendingIntent.FLAG_ONE_SHOT

    notificationManager.notify(MY_ID, notification);
}