AlarmManager doesn't starts at the right time even when the clock matches the time

Question

I'm trying to make an app that should start every day at 17 o’clock. If I use "calendar.set ()" and lets say its 18 o´clock the alarm starts immediately after I set it. In the other hand if I use "calendar.add ()" it does not work, I mean even when the device clock matches the value that I set, for example, 17 o´clock, the alarm does not start at all.

     Calendar calendar = Calendar.getInstance();

 //calendar.add(Calendar.HOUR_OF_DAY, 17);
 //calendar.add(Calendar.MINUTE, 0);
 //calendar.add(Calendar.SECOND, 0);

 calendar.set(Calendar.HOUR_OF_DAY, 17);
 calendar.set(Calendar.MINUTE, 0);
 calendar.set(Calendar.SECOND, 0);

 Intent intent = new Intent(this, MyBroadcastReceiver.class);

    PendingIntent pendingIntent = PendingIntent.getBroadcast(this.getApplicationContext(), 123, intent, PendingIntent.FLAG_UPDATE_CURRENT);

    AlarmManager alarmManager = (AlarmManager) getSystemService(ALARM_SERVICE); 
    alarmManager.set(AlarmManager.RTC_WAKEUP, calendar.getTimeInMillis(), pendingIntent);

What I'm missing here? Thanks

Answer 1

You need to increase the DAY_OF_YEAR field by one if the current time is past 17:00.

Calendar.getInstance() instantiates a new Calendar object using the current time. Let's pretend when this line is executed it's 18:00 on July 1st. After you set the hours, minutes, and seconds, the calendar now stores 17:00 on July 1st. When you set the alarm, AlarmManager sees this time is in the past and fires the alarm immediately.