AlarmManager不定期射击

Question

I'm working on an app that involves an AlarmManager, and I can't seem to get it to fire. I was using a Handler originally, but I switched over to the AlarmManager so that I can wake the phone up from sleep.

Here's what I have so far:

int timeBetweeninMillis = 3 * 60000;    
if (ManagerService.serviceRunning) {
            Intent alarmIntent = new Intent(AlarmReceiver.ACTION_RECEIVE);
            PendingIntent alarmPendingIntent = PendingIntent.getBroadcast(getApplicationContext(), 400, alarmIntent, PendingIntent.FLAG_UPDATE_CURRENT);
            mAlarmManager.set(AlarmManager.ELAPSED_REALTIME_WAKEUP, (SystemClock.elapsedRealtime() + timeBetweeninMillis), alarmPendingIntent);
        }

The AlarmManager either won't fire or will fire extremely late (like 10 minutes after).

The app is written with API 16 and is being tested on a phone with API 19.

Thank you for your help!

Answer 1

There's an issue with new PendingIntent s recycling existing PendingIntent s that might cause issues with AlarmManager .

To workaround that, I always add a unique value to all my PendingIntent s, this one-liner does the trick in most cases:

Intent alarmIntent = new Intent(AlarmReceiver.ACTION_RECEIVE);

alarmIntent.setData(Uri.parse("custom://" + System.currentTimeMillis())); // MAKE INTENT UNIQUE

PendingIntent alarmPendingIntent = PendingIntent.getBroadcast(getApplicationContext(), 400, alarmIntent, PendingIntent.FLAG_UPDATE_CURRENT);
mAlarmManager.set(AlarmManager.ELAPSED_REALTIME_WAKEUP, (SystemClock.elapsedRealtime() + timeBetweeninMillis), alarmPendingIntent);

Also, I don't know what's ManagerService.serviceRunning in your code, but I would add some log to the else case to make sure you're actually running that code block.

EDIT:

try using mAlarmManager.setExactAndAllowWhileIdle instead of mAlarmManager.set this will force AlarmManager to call your code exactly when requested, and prevent device idle time from interfering with the alarm.

See: https://developer.android.com/reference/android/app/AlarmManager.html#setExactAndAllowWhileIdle(int, long, android.app.PendingIntent)