Question

I just went through this tutorial:
update-widget-in-onreceive-method
(btw: would you propose any improvements to that code?)

At the end someone mentions:

I’m just wondering if there is a way to extend this further so that when the device is asleep (screen off), the updates stop. Then when the device wakes up, the updates resume.

So my question: is there a way of doing this? how?
or is the alarmmanager automatically stopped? – I don’t think so.

Answer 1

You can specify whether the device will wake up when scheduling the AlarmManager.

Quote from the documentation:

ELAPSED_REALTIME
Alarm time in SystemClock.elapsedRealtime() (time
since boot, including sleep). This alarm does not wake the device up; if it goes off while the device is asleep, it will not be delivered until the next time the device wakes up.

ELAPSED_REALTIME_WAKEUP
Alarm time in
SystemClock.elapsedRealtime() (time since boot, including sleep),
which will wake up the device when it goes off.

Same goes for AlarmManager.RTC and AlarmManager.RTC_WAKEUP

So you probably want one of the two AlarmManager.RTC or AlarmManager.ELAPSED_REALTIME. These continue while the device is awake and stop when the device is in standby. If this alarm is triggered while the device is asleep it will be delivered when the user turns the device back on though, exactly what you want. And no, the AlarmManagers scheduled alarms are not cancelled automatically in general.

The part mentioned here can be found in this part of the tutorial, specific this line:

alarmManager.setRepeating(AlarmManager.RTC_WAKEUP, calendar.getTimeInMillis(), 20*1000, pendingIntent);