CODEWITHSUNDEEP
androidalarmmanager
yuttadhammo
yuttadhammo

Reputation: 5199

Why is AlarmManager alarm delayed on first run?

Recently, in my timer app, running the timer for the first time causes it to fire an alarm approximately two or three seconds after it should. The strange this is, it only does this the first time I run the timer after installing the app via Android Studio. Every time after that, it runs as expected and the timer goes off after the expected time.

Here is the relevant code:

        if(LOG) Log.v(TAG,"Starting the timer service: "+ TimerUtils.time2humanStr(context, mTime));

        Intent intent = new Intent( this, TimerReceiver.class);
        mPendingIntent = PendingIntent.getBroadcast( this, 0, intent, PendingIntent.FLAG_UPDATE_CURRENT);
        mAlarmMgr.set(AlarmManager.ELAPSED_REALTIME, SystemClock.elapsedRealtime() + mTime, mPendingIntent);

The variable mTime is set properly each time, according to the logcat output:

Starting the timer service: 5 seconds

And it works fine every time after the initial run. It was working fine before; could it be a problem with Android or Android Studio? Or am I needing to initialize something? I know I can't expect precise answers without dumping all my code here, I'm just looking for hints (speculation?) as to why this behaviour might be occurring.

Upvotes: 3

Views: 938

Answers (1)

JstnPwll
JstnPwll

Reputation: 8695

Are you using API 19? Check out this note in the documentation:

Note: Beginning in API 19, the trigger time passed to this method is treated as inexact: the alarm will not be delivered before this time, but may be deferred and delivered some time later. The OS will use this policy in order to "batch" alarms together across the entire system, minimizing the number of times the device needs to "wake up" and minimizing battery use. In general, alarms scheduled in the near future will not be deferred as long as alarms scheduled far in the future.

Source: AlarmManager

Upvotes: 1

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