Weird AlarmManager behaviour

Question

I have 2 BroadcastReceivers and 2 intents, I want to click a button, 5m later start broadcast1 and 10m later start broadcast2, what's happening is they both start 10m after I click, My guess is, the intents are not unique, but I'm setting a diffrent reqeustCode for each of them.

Button's OnClick:

    Bundle bd = new Bundle();
    bd.putInt("mInt", i);

    Intent intent1 = new Intent(getActivity(), Broadcast_1.class);
    intent1.putExtras(bd);
    PendingIntent pendingIntent1 = PendingIntent.getBroadcast(getActivity().getApplicationContext(), i, intent1, PendingIntent.FLAG_UPDATE_CURRENT);
    AlarmManager alarmManager1 = (AlarmManager) getActivity().getApplicationContext().getSystemService(Context.ALARM_SERVICE);
    alarmManager1.setRepeating(AlarmManager.RTC, System.currentTimeMillis()+1000*60*5, 1000*60*10, pendingIntent1);
    Toast.makeText(getActivity(), "countdown started "+i ,Toast.LENGTH_SHORT).show();

    Intent intent2 = new Intent(getActivity(), Broadcast_1.class);
    intent2.putExtras(bd);
    PendingIntent pendingIntent2 = PendingIntent.getBroadcast(getActivity().getApplicationContext(), i+42212342, intent2, PendingIntent.FLAG_UPDATE_CURRENT);
    AlarmManager alarmManager2 = (AlarmManager) getActivity().getApplicationContext().getSystemService(Context.ALARM_SERVICE);
    alarmManager2.setRepeating(AlarmManager.RTC, System.currentTimeMillis()+1000*60*10, 1000*60*10, pendingIntent2);

BroadcastReceiver_1 and _2 (they look the same) class:

public class Broadcast_1 extends BroadcastReceiver {

    @Override
    public void onReceive(Context context, Intent intent) {

        Calendar c = Calendar.getInstance();
        int seconds = c.get(Calendar.SECOND);
        int minutes = c.get(Calendar.MINUTE);
        ShowTextFragment.setText("Broadcast_1" + " at " + minutes + " : " + seconds);

    }

}

Question: Why does the most recent intent push the previous intents to his starting time?

I confirmed this behaviour by printing the time when the Broadcast's code executes. Please help

Answer 1

The problem you are seeing is the way that repeating alarms now work. In order to preserve battery life, the AlarmManager now takes great liberties in rescheduling alarms in order to group multiple alarms together. Basically, if you need any sort of accurate timing you should forget about using setRepeating(). Use setExact() instead. If you need a repeating alarm, just reset it when it goes off.