android prevent immediate trigger of alarm service

2018-12-31 23:12发布

问题:

The reference for Alarm Manager says that

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

I am facing this problem in my application. Here is my alarm manager code :

Intent myIntent = new Intent(getActivity(), DinnerAlarmReceiver.class);
                pendingDinnerIntent = PendingIntent.getBroadcast(getActivity(), 0, myIntent, 0);

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

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

Is there any workaround to this problem?

-----EDIT------

I have written some code to estimate if the set time for the alarm is before the current time . Here is the above portion with corresponding changes :

Calendar calendar = Calendar.getInstance();
                long currentTime = calendar.getTimeInMillis();
                calendar.set(Calendar.HOUR_OF_DAY, hourOfDay);
                calendar.set(Calendar.MINUTE, minute);
                long setTime = calendar.getTimeInMillis();
                Timestamp setTimestamp = new Timestamp(setTime);
                Timestamp currentTimestamp = new Timestamp(currentTime);
                if (setTimestamp.after(currentTimestamp))
                {
                    alarmManager.set(AlarmManager.RTC_WAKEUP,
                            calendar.getTimeInMillis(), pendingDinnerIntent);
                }
                else
                {
                }

What should I the alarmManager to in case setTimestamp is before currentTimestamp ?

回答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.