What ID numbers to use for Notifications

Question

public static final int NOTIFY_FAILED = 1;

private final Notification displayErrorNotification = new Notification(R.drawable.notification, "Communication Error", System.currentTimeMillis());
private void displayNotificationError(String message) {
    PendingIntent contentIntent = PendingIntent.getActivity(this, 0, new Intent(), 0);
    displayErrorNotification.number++;
    displayErrorNotification.setLatestEventInfo(getApplicationContext(), "Failed x ("+displayErrorNotification.number+")", message, contentIntent);
    notificationManager.notify(NOTIFY_FAILED, displayErrorNotification);
}

In this example I have used 1 for failed notifications but what if other programs also use the number 1 for their notifications.

What would happen when I do this:

notificationManager.cancel(NOTIFY_FAILED);