AlarmManager.set(…) behavior not matching documentation. Am I doing something wrong?

Question

I'm setting up alarms using this code

//in onCreate()
mAlarmManager = (AlarmManager) getApplicationContext()
            .getSystemService(ALARM_SERVICE);

//called for each timer I schedule
Intent intent = new Intent (Intents.MY_INTENT_ACTION);
PendingIntent pendIntent = PendingIntent.getBroadcast(
    getApplicationContext(), alert.getID(), 
    intent, PendingIntent.FLAG_ONE_SHOT);
long delay = 1000 * alert.getDuration();
Calendar cal = Calendar.getInstance();
mAlarmManager.set(AlarmManager.RTC_WAKEUP,
    cal.getTimeInMillis() + delay, pendIntent);

But the behavior I'm seeing doesn't match what I should see in the documtation1,

public void set(int type, long triggerAtTime, PendingIntent operation)

If there is already an alarm scheduled for the same IntentSender, it will first be canceled...If there is already an alarm for this Intent scheduled (with the equality of two intents being defined by filterEquals(Intent)), then it will be removed and replaced by this one...

which suggests that calling set(int type, long triggetAtTime, PendingIntent operation) for an already alarmed intent should replace the old alarm for that intent. I'm not seeing any alarms get dropped. Instead, every alarm i set fires, despite the fact that the intents that are fired by the pending intents should all match (by filterEquals(intent)), since all I've set on each intent is an identical action.

Am I doing something wrong, or is the API not behaving as documented?

Note: changing the PendingIntent instantiation to

PendingIntent pendIntent = PendingIntent.getBroadcast(
getApplicationContext(), CONSTANT_ID,
intent, PendingIntent.FLAG_ONE_SHOT);

Behaves as expected, dropping any already set alarm, and replacing it with a new alarm.

Answer 1

It appears the consensus is that the documentation for AlarmManager.set(), as well as other AlarmManager methods claiming that Intents (not just the wrapping PendingIntents) are compared to check whether a particular alarm is already set.

Do not rely on AlarmManager matching Intents, instead rely on the matching of PendingIntents, which appears to be working as advertised.

Answer 2

Maybe it is because you are giving each alarm a different ID (Does alert.getID() give different ID's or not?). By the documentation, it shouldn't matter but yet you should still try.

If it doesn't work too, hold a reference for your last set alarm, and when you need it to be canceled, cancel it yourself then set the next one.

Answer 3

Have you tried with PendingIntent flag : PendingIntent.FLAG_UPDATE_CURRENT intead of PendingIntent.FLAG_ONE_SHOT?