Question

I am using bitwise operation to store availability with 1 bit representing one minutes. So one day of availability can be represented by 1 long (8 bytes so 60 bits out of 64 bits) can be used to represent 1 hour so 24 longs will represent availability per day.

Now I have a range of times (ex. 2:00 – 4:00, 15:00 to 17:00) and I need to translate this into bit mask to compare against above longs of availabilities to see if the ranges in the mask is available or unavailable (& with mask) what is the best way to translate this range of times to bits?

Answer 1

I think this works:

private static int getMinuteOfDay(Date date) {
    Calendar cal = new GregorianCalendar();

    cal.setTime(date);

    return cal.get(Calendar.HOUR_OF_DAY) * 60 + cal.get(Calendar.MINUTE);
}

private static void addAvailability(Date startTime, Date endTime, BitSet bs) {

    int startMinute = getMinuteOfDay(startTime);
    int endMinute = getMinuteOfDay(endTime);

    bs.set(startMinute, endMinute);
}

private static boolean timeIsAvailable(Date time, BitSet bs) {
    return bs.get(getMinuteOfDay(time));
}

static DateFormat TIME_FORMAT = new SimpleDateFormat("HH:MM:ss");

public static void main(String[] args) {
    BitSet availability = new BitSet();

    try {
        addAvailability(TIME_FORMAT.parse("02:00:00"), TIME_FORMAT.parse("04:00:00"), availability);
        addAvailability(TIME_FORMAT.parse("15:00:00"), TIME_FORMAT.parse("17:00:00"), availability);

        System.out.println(timeIsAvailable(TIME_FORMAT.parse("01:19:00"), availability));
        System.out.println(timeIsAvailable(TIME_FORMAT.parse("02:00:00"), availability));
        System.out.println(timeIsAvailable(TIME_FORMAT.parse("02:01:00"), availability));
        System.out.println(timeIsAvailable(TIME_FORMAT.parse("04:00:00"), availability));
        System.out.println(timeIsAvailable(TIME_FORMAT.parse("04:01:00"), availability));
        System.out.println(timeIsAvailable(TIME_FORMAT.parse("16:00:00"), availability));
        System.out.println(timeIsAvailable(TIME_FORMAT.parse("17:10:00"), availability));

    } catch (ParseException e) {
        throw new RuntimeException(e);
    }

}

Results:

false
true
true
false
false
true
false