Why my Alarm is fired earlier than my set time?

Question

I'm currently trying to make an alarm app that will mute all audio volume at the user-defined day and time. However, the alarm seems not fired at the correct time. I found that the alarm is always fired earlier.

This is my set alarm code:

public static void setAlarm(Context context, String time, int day, int reqCode) {
    String[] timeSplit = time.split(":");
    Calendar calendar = Calendar.getInstance();

    int hour = Integer.parseInt(timeSplit[0]);
    int minute = Integer.parseInt(timeSplit[1]);
    int days = (day-calendar.get(Calendar.DAY_OF_WEEK) + calendar.get(Calendar.DAY_OF_MONTH));

    calendar.set(
            calendar.get(Calendar.YEAR),
            calendar.get(Calendar.MONTH),
            days,
            hour,
            minute,
            0
    );

    AlarmManager alarmManager = (AlarmManager) context.getSystemService(Context.ALARM_SERVICE);
    Intent intent = new Intent(context, RuleAlarm.class);

    PendingIntent pendingIntent = PendingIntent.getBroadcast(context, reqCode, intent, 0);

    // Set the alarm to be fired every week on the selected day
    alarmManager.setRepeating(AlarmManager.RTC, calendar.getTimeInMillis(), 7 * 24 * 60 * 60 * 1000, pendingIntent);

    Toast.makeText(context, "Alarm is set", Toast.LENGTH_SHORT).show();
}

I have tried to change setRepeating() to setInexactRepeating() but nothing changed.

Answer 1

I finally find out the problem. It lies on the day params. What I pass to day params is my Spinner selected position which starts from zero while the Calendar days starts from one (SUNDAY = 1, MONDAY = 2, so on). So, the alarm will always be set in the past days. I plus one to the day params and it's worked.

This is my piece of code where the startAlarm() function got called.

String ruleStartTime = rule_startTime.getText().toString();

// Spinner index starts from zero,
// to match with the Calendar day indexing, we need to plus it one
int dayIdx = day.getSelectedItemPosition()+1;

Alarm.setAlarm(getApplicationContext(), ruleStartTime,
                        dayIdx, 0);