Android – duplicate alerts don’t work

I know this kind of question has been laughed at many times... But please read my question first, and then vote or mark it as repeated

I have mentioned many so problems, such as this, for managing alerts, but I can't find any solution, so I'm here

In my application, I want to trigger a repeat alarm at 8 a.m. every day, and others are specified by the user

First of all, I'm tired of using setrepeating to repeat the alarm clock... This is my code

Calendar calendar = Calendar.getInstance();
            calendar.add(Calendar.DATE, 1);
            calendar.set(Calendar.HOUR_OF_DAY, 8);
            calendar.set(Calendar.MINUTE, 0);
            calendar.set(Calendar.SECOND, 0);
            calendar.set(Calendar.AM_PM,Calendar.AM);
            //calendar.set(Calendar.MILLISECOND, 0);


            AlarmManager am = (AlarmManager) getSystemService(ALARM_SERVICE);
            Intent pintent = new Intent(this, AlarmReceiver.class);

            pintent.putExtra("id", 0);
            pintent.putExtra("ontime", false);

            PendingIntent pendingIntent = PendingIntent.getBroadcast(this, 0,
                    pintent, PendingIntent.FLAG_UPDATE_CURRENT);


            am.setRepeating(AlarmManager.RTC_WAKEUP,calendar.getTimeInMillis(),AlarmManager.INTERVAL_DAY,pendingIntent);

In fact, the problem is that the alarm does not fire after a long sleep. If it is tested with the changed date and time, it will have a fire... But it will stop firing after one night

So I switch to the second option mentioned in the given link. I use setexact to set the alarm as follows and rearrange it every time I fire

 Calendar calendar = Calendar.getInstance();
            calendar.add(Calendar.DATE, 1);
            calendar.set(Calendar.HOUR_OF_DAY, 8);
            calendar.set(Calendar.MINUTE, 0);
            calendar.set(Calendar.SECOND, 0);
            calendar.set(Calendar.AM_PM,Calendar.AM);
            //calendar.set(Calendar.MILLISECOND, 0);


            AlarmManager am = (AlarmManager) getSystemService(ALARM_SERVICE);
            Intent pintent = new Intent(this, AlarmReceiver.class);

            pintent.putExtra("id", 0);
            pintent.putExtra("ontime", false);

            PendingIntent pendingIntent = PendingIntent.getBroadcast(this, 0,
                    pintent, PendingIntent.FLAG_UPDATE_CURRENT);

            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
                AlarmManager.AlarmClockInfo alarmClockInfo = new AlarmManager.AlarmClockInfo(calendar.getTimeInMillis(), pendingIntent);
                am.setAlarmClock(alarmClockInfo, pendingIntent);
            } else if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
                am.setExact(AlarmManager.RTC_WAKEUP, calendar.getTimeInMillis(), pendingIntent);
            } else
                am.set(AlarmManager.RTC_WAKEUP, calendar.getTimeInMillis(), pendingIntent);

But I have the same problem. It is not repeated every day. Please also consider that this is only an example of my default alarm clock. According to the user's specification, there can be n alarms without precision and repetition

Someone also suggested that I use the service instead of the alarm manager, but my service may be killed, so I dare not use it. Another solution is to check the deadline and set all alarms every day, but I don't think this is the right way. Is it?

Please suggest any other methods or help me improve my code. I really need this work. Thanx all. My test equipment is HTC one X (4.3), redmi prime (6.0) and mi4i (5.0.2)

resolvent:

I had a lot of problems setting up duplicate alerts, but finally this code is running on all my test devices, which may help:

    // set time
    Calendar c = Calendar.getInstance();
    c.setTimeInMillis(System.currentTimeMillis());
    c.set(Calendar.HOUR_OF_DAY, 8);
    c.set(Calendar.MINUTE, 0);
    c.set(Calendar.SECOND, 0);

    long startUpTime = c.getTimeInMillis();

    // startupTime + 24 hours if alarm is in past
    if (System.currentTimeMillis() > startUpTime) {
        startUpTime = startUpTime + 24 * 60 * 60 * 1000;
    }

    // initialize alarm
    AlarmIntent alarmIntent = new Intent(MainActivity.this, AlarmReceiver.class);
    PendingIntent pendingIntent = PendingIntent.getBroadcast(MainActivity.this, 0, alarmIntent, 0);

    manager.setInexactRepeating(AlarmManager.RTC_WAKEUP, startUpTime, 24 * 60 * 60 * 1000, pendingIntent);