Android Alarm Manager not working with specific date and time

Question

So I have been working on medication intake app, where I need to remind the user locally ( no internet/push notification needed) about taking their medication. I am using Android Alarm manager for this. Below is the code Note I am trying to schedule the alarm for a specific date: "13 July 2018 at 3h30 PM". I schedule and wait but the reminder didn't fire (so not broadcast) however if I used AlarmManager.ELAPSED_REALTIME_WAKEUP with a defined amount of millisecond it does fire ( but AlarmManager.RTC_WAKEUP just does not work) `

    AlarmManager manager = (AlarmManager)getSystemService(Context.ALARM_SERVICE);
    Intent myIntent;
    PendingIntent pendingIntent;
    long reminderDateTimeInMilliseconds = 000;

    myIntent = new Intent(this,MedicationScheduleBroadCastReceiver.class);

    pendingIntent = PendingIntent.getBroadcast(this,0,myIntent,PendingIntent.FLAG_UPDATE_CURRENT);

    //TODO : Reminder the user to take medication on the 13th July 2018 at 15:30
    Calendar calendarToSchedule = Calendar.getInstance();

    calendarToSchedule.set(Calendar.YEAR, 2018);
    calendarToSchedule.set(Calendar.MONTH, 07);
    calendarToSchedule.set(Calendar.DAY_OF_MONTH, 13);
    calendarToSchedule.set(Calendar.HOUR_OF_DAY, 15);
    calendarToSchedule.set(Calendar.MINUTE, 30);

    reminderDateTimeInMilliseconds = calendarToSchedule.getTimeInMillis();

    if(android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.O){

        manager.setExactAndAllowWhileIdle(AlarmManager.RTC_WAKEUP, reminderDateTimeInMilliseconds, pendingIntent);
    }
    else{

        manager.set(AlarmManager.RTC_WAKEUP, reminderDateTimeInMilliseconds, pendingIntent);
    }

`

score 6 · Accepted Answer · answered Aug 21 '18 at 10:44

So I figure out the issue, the main issue was the calendar month in Java is actually 0 index based so ( Jan:0 - Dec:11) so below is the updated code.

AlarmManager manager = (AlarmManager)getSystemService(Context.ALARM_SERVICE);
Intent myIntent;
PendingIntent pendingIntent;
long reminderDateTimeInMilliseconds = 000;

myIntent = new Intent(this,MedicationScheduleBroadCastReceiver.class);

pendingIntent = PendingIntent.getBroadcast(this,0,myIntent,PendingIntent.FLAG_UPDATE_CURRENT);

//TODO : Reminder the user to take medication on the 13th July 2018 at 15:30
// Note: For the month of July the int value will actuall be 6 instead of 7
Calendar calendarToSchedule = Calendar.getInstance();
calendarToSchedule.setTimeInMillis(System.currentTimeMillis());
calendarToSchedule.clear();

//.Set(Year, Month, Day, Hour, Minutes, Seconds);
calendarToSchedule.set(2018, 06, 13, 15, 30, 0);


reminderDateTimeInMilliseconds = calendarToSchedule.getTimeInMillis();

if(android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.O){

    manager.setExactAndAllowWhileIdle(AlarmManager.RTC_WAKEUP, reminderDateTimeInMilliseconds, pendingIntent);
}
else{

    manager.set(AlarmManager.RTC_WAKEUP, reminderDateTimeInMilliseconds, pendingIntent);
}

Better use Calendar.getInstance(); with custom or default Locale: Calendar.getInstance(Locale.getDefault()); Nice answer. Thanks! — Joan Casadellà, Sep 26 '19 at 14:22
Oh my god! Thank you so much!! I've been stuck on this for days now... It finally works now, phew! — Crazzygamerr, Nov 26 '21 at 10:37

score 0 · Answer 2 · answered Jul 13 '18 at 12:00

0

Alarms are not fired if device is in Doze mode. Use setAndAllowWhileIdle or setExactAndAllowWhileIdle for alarms to be fired in Doze mode also.

From the Android Doc.

Network access is suspended.
The system ignores wake locks.
Standard AlarmManager alarms (including setExact() and setWindow()) are deferred to the next maintenance window. If you need to set alarms that fire while in Doze, use setAndAllowWhileIdle() or setExactAndAllowWhileIdle().
Alarms set with setAlarmClock() continue to fire normally — the system exits Doze shortly before those alarms fire.
The system does not perform Wi-Fi scans.
The system does not allow sync adapters to run. The system does not allow JobScheduler to run.

answered Jul 13 '18 at 12:00

Khemraj Sharma

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But as you can see for all devices/emulator that have API level 26 and above I am actually using what you have mentioned "setExactAndAllowWhileIdle" and FYI I am testing on a device that have Android Oreo but still can't get it to fire – Jude Babs Babandakana Jul 13 '18 at 12:06
You can see work manager, i have switched to WorkManger from AlarmManager (due to unreliable behaviour) – Khemraj Sharma Jul 13 '18 at 12:10
but what I am trying to accomplish, it is apparently more appropriate to use AlarmManager to do it than workManager, see below link: https://stackoverflow.com/questions/50299814/how-to-schedule-notifications-using-workmanager – Jude Babs Babandakana Jul 13 '18 at 12:18
Yes thanks for correcting me, Your requirement needs Alarm Manager. – Khemraj Sharma Jul 13 '18 at 12:22
Let me test your case, I'll get back to you. – Khemraj Sharma Jul 13 '18 at 12:22
I think that you should be using setAlarmClock() because while setExactAndAllowWhileIdle() can fire during doze maintenance windows, it is still subject to delays...[setExactAndAllowWhileIdle is not exact](https://stackoverflow.com/questions/33110246/setexactandallowwhileidle-is-not-exact-as-of-developer-reference) – Elletlar Jul 13 '18 at 14:58
@Elletlar this did not help. – Jude Babs Babandakana Jul 24 '18 at 07:41
Can you tell a bit more? what is causing issue.? – Khemraj Sharma Jul 24 '18 at 07:43

Android Alarm Manager not working with specific date and time

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