Android setting alarm to a past date

Question

What happens should I add an alarm but set the starting date to a past date?

Does is get executed immediately or is it put in the queue and never executed?

alarmManager.setRepeating(AlarmManager.RTC_WAKEUP, startDate, repeatingValue, alarmIntent);

Answer 1

从文档中 ，如果startDate时间是过去的，则会立即触发警报。

Answer 2

If the date is in past then alarm will trigger immediately. However you may try to use setInexactRepeating instead of setRepeating :

alarmManager.setRepeating(AlarmManager.RTC_WAKEUP, startDate, setInexactRepeating , alarmIntent);

From the setInexactRepeating() docs :

Schedule a repeating alarm that has inexact trigger time requirements; for example, an alarm that repeats every hour, but not necessarily at the top of every hour.

Answer 3

Actually AlarmManager works with the current time. So when you will set past date alarm then AlarmManager will execute

public void onReceive(Context context, Intent intent)
{
}

method.

Answer 4

我认为警报只设置了几个小时（至少通过Android用户界面），而不是特定的一天，这样它将在你设置的确切hour:minute开始。

Answer 5

As i can conclude from my previous experience with AlarmManager . Date that is in the past will trigger alarm immediately.

Answer 6

As far as I can tell, AlarmManager.set will execute now when the time is set to a past time, the documentation says as much. This sentence is missing for AlarmManager.setInexactRepeating , this alarm will not trigger when it's set for a past time, it will trigger at the next interval, starting from the given time.

Answer 7

AlarmManager.set and AlarmManager.setInexactRepeating are both calling setImpl, with the triggertime they got passed as parameter (checked in Android 7.1.2 sources). --> there's no difference in both methods, if the triggertime is in the past.