AlarmManager firing alarm past the time it was set

问题:

So basically I have this code, time returns 24hour time and repeats the alarm daily.

public setAlarm(String time, Context context){
    String[] strTime;

    strTime = time.split(":");

    int hour, min, sec;
    //set when to alarm
    hour = Integer.valueOf(strTime[0]);
    min = Integer.valueOf(strTime[1]);
    sec = 0;

    Calendar cal = Calendar.getInstance();
    cal.set(Calendar.HOUR_OF_DAY, hour);
    cal.set(Calendar.MINUTE, min);
    cal.set(Calendar.SECOND, sec);
    //Create a new PendingIntent and add it to the AlarmManager
    Intent intent = new Intent(context, AlarmReceiverActivity.class);
    PendingIntent pendingIntent = PendingIntent.getActivity(context, 19248, intent, PendingIntent.FLAG_UPDATE_CURRENT);
    AlarmManager am = (AlarmManager) context.getSystemService(Activity.ALARM_SERVICE);
    am.setRepeating(AlarmManager.RTC_WAKEUP, cal.getTimeInMillis(), AlarmManager.INTERVAL_DAY, pendingIntent);
}

Anyways, the problem is when I set the alarm 9am while the time is 9:10am, the alarm will go off. Why? I want it not to alarm if it is set past the system time. Ex. set the alarm at 9am while the system time is 9:10am

回答1:

I got it working now. I added a checker of the alarm time and current time.

public setAlarm(String time, Context context){
        String[] strTime;

        strTime = time.split(":");

        int hour, min, sec;
        //set when to alarm
        hour = Integer.valueOf(strTime[0]);
        min = Integer.valueOf(strTime[1]);
        sec = 0;

        long _alarm = 0;
        Calendar now = Calendar.getInstance();
        Calendar alarm = Calendar.getInstance();
        alarm.set(Calendar.HOUR_OF_DAY, hour);
        alarm.set(Calendar.MINUTE, min);
        alarm.set(Calendar.SECOND, sec);

        if(alarm.getTimeInMillis() <= now.getTimeInMillis())
            _alarm = alarm.getTimeInMillis() + (AlarmManager.INTERVAL_DAY+1);
        else
            _alarm = alarm.getTimeInMillis();               

        //Create a new PendingIntent and add it to the AlarmManager
        Intent intent = new Intent(context, AlarmReceiverActivity.class);
        PendingIntent pendingIntent = PendingIntent.getActivity(context, 19248, intent, PendingIntent.FLAG_CANCEL_CURRENT);
        AlarmManager am = (AlarmManager) context.getSystemService(Activity.ALARM_SERVICE);
        am.setRepeating(AlarmManager.RTC_WAKEUP, _alarm, AlarmManager.INTERVAL_DAY, pendingIntent);
    }

回答2:

The accepted answer is wrong as I tried it and then figured out the solution.

It is wrong because, as you can see here: Calendar now = Calendar.getInstance(); Calendar alarm = Calendar.getInstance(); alarm.set(Calendar.HOUR_OF_DAY, hour); alarm.set(Calendar.MINUTE, min); alarm.set(Calendar.SECOND, sec);

"Calendar now" and "Calendar alarm" will always be the same no matter what because they are doing the same thing almost at the exact same spot in the code so the Calendar.getInstance() wil always be the same.

The solution is this

    long _alarm;
    Calendar now = Calendar.getInstance();
    long oldtimer = now.getTimeInMillis();

    cal.set(Calendar.HOUR_OF_DAY, Hours2int);
    cal.set(Calendar.MINUTE, minutes2int);
    cal.set(Calendar.SECOND, cur_cal.get(Calendar.SECOND));
    cal.set(Calendar.MILLISECOND, cur_cal.get(Calendar.MILLISECOND));
    cal.set(Calendar.DATE, cur_cal.get(Calendar.DATE));
    cal.set(Calendar.MONTH, cur_cal.get(Calendar.MONTH));

    //Calendar alarm = Calendar.getInstance();

    long newtimer = cal.getTimeInMillis();


    if(newtimer < oldtimer) {
        //do the thing
    }

回答3:

Use setInexactRepeating instead of setRepeating

    Calendar cal= Calendar.getInstance();
    cal.set(Calendar.HOUR_OF_DAY, 9);
    cal.set(Calendar.MINUTE, 0);
    cal.set(Calendar.SECOND, 0);
    PendingIntent pi = PendingIntent.getService(context, 0,
        new Intent(context, MyClass.class),PendingIntent.FLAG_UPDATE_CURRENT);
    AlarmManager am = (AlarmManager) context.getSystemService(Context.ALARM_SERVICE);
   am.setRepeating(AlarmManager.RTC_WAKEUP, cal.getTimeInMillis(),
                            AlarmManager.INTERVAL_DAY, pi);