android - AlarmManager - How to repeat an alarm at the top of every hour?

Question

I want for an event to fire every hour (at 5:00, 6:00, 7:00, etc...). I tried with a persistent background service with a thread but it wasn't the right solution because of:

• battery consumption
• service termination, due to android memory management

So I'm trying with AlarmManager. It works if I set an alarm to fire in X seconds (using "set" method). But how can I repeat an event (using "setRepeating" method) at the top of every hour, until the alarm is canceled?

Thanks!

Answer 1

When you set alarms you have two times: First trigger time, and the next trigger interval.

You then have to calculate the remaining miliseconds to the next top of the hour, then set one hour for the repeating interval.

// We want the alarm to go off 30 seconds from now.
long firstTime = SystemClock.elapsedRealtime();
firstTime += remainingMilisecondsToTopHour;
long a=c.getTimeInMillis();

// Schedule the alarm!
AlarmManager am = (AlarmManager)ctx.getSystemService(Context.ALARM_SERVICE);
am.setRepeating(AlarmManager.ELAPSED_REALTIME,
c.getTimeInMillis(), 1*60*60*1000, sender);