移除和重新添加后，接近警报触发两次

Question

I am having a problem with the proximity alert. I have settings on my android application where users can disable/enable proximity alert of some locations. When they disable the proximity alert everything works great and they will not be notified, but if they disable and the re-enable the proximity alert, it adds again and they will get a notification twice when they reach a location and so on. So basically every time they re-enable it, it creates a new proximity alert.

This is the code I use to remove the proximity alert:

private void removeProximityAlert(int id) {
    final LocationManager manager = (LocationManager) getSystemService( Context.LOCATION_SERVICE );
    Intent intent = new Intent(PROX_ALERT_INTENT + id);
    PendingIntent proximityIntent = PendingIntent.getBroadcast(this, id, intent, PendingIntent.FLAG_CANCEL_CURRENT);
    manager.removeProximityAlert(proximityIntent);
}

And this is the code that I use to add a proximity alert:

private void addProximityAlert(double latitude, double longitude, int id, int radius, String title) {
    final LocationManager manager = (LocationManager) getSystemService( Context.LOCATION_SERVICE );
    Intent intent = new Intent(PROX_ALERT_INTENT + id);
    PendingIntent proximityIntent = PendingIntent.getBroadcast(this, id, intent, PendingIntent.FLAG_CANCEL_CURRENT);
    manager.addProximityAlert(
           latitude,
           longitude,
           radius,
           -1,
           proximityIntent
    );

    IntentFilter filter = new IntentFilter(PROX_ALERT_INTENT + id);
    registerReceiver(new ProximityIntentReceiver(id, title), filter);
}

Answer 1

My understanding of FLAG_CANCEL_CURRENT is that it tells the system that the old pending intent is no longer valid and it should cancel it and then create a fresh one. Correct me if I am wrong. This, I believe, is why you are duplicating Proximity Alerts with each cancel and creation.

Resolution:

In your removeProximityAlert I would change the following line

PendingIntent proximityIntent = PendingIntent.getBroadcast(this, id, intent, PendingIntent.FLAG_CANCEL_CURRENT);

to:

PendingIntent proximityIntent = PendingIntent.getBroadcast(this, id, intent, PendingIntent.FLAG_UPDATE_CURRENT).cancel();

FLAG_UPDATE_CURRENT returns the existing one created, if any. cancel() should take care of the rest for you.

---

Edit

If I break the cancel() into a separate line I don't get any errors. Try this:

PendingIntent proximityIntent = PendingIntent.getBroadcast(this, id, intent, PendingIntent.FLAG_UPDATE_CURRENT);
proximityIntent.cancel();

Answer 2

The problem is that you're registering the receiver each time you add the alarm. You should register it only once.