android prevent immediate trigger of alarm service if alarm time has passed for the day

Question

The reference for Alarm Manager says that

If the stated trigger time is in the past, the alarm will be triggered immediately.

Answer 1

You don't need to create Timestamps. You can do it with your Calendar.

Calendar calendar = Calendar.getInstance();
calendar.set(Calendar.HOUR_OF_DAY, hourOfDay);
calendar.set(Calendar.MINUTE, minute);

if(calendar.before(Calendar.getInstance())) {
    calendar.add(Calendar.DATE, 1);
}

alarmManager.set(AlarmManager.RTC_WAKEUP,
    calendar.getTimeInMillis(), pendingDinnerIntent);

I would also mention that as of KitKat, if your targetSdkVersion is 19 or above, the AlarmManager#set() method is not exact. If you want your alarm to fire at an exact time, you'll need to use a setExact*() method.