Java Program for calculating business days considering public holidays

This is in continuation to my previous post...

This is a Java Program for calculating business days considering public holidays

public long getNumberOfBusinessDays(Date start, Date end) 
    {
        if (start == null || end == null)  
            return 0;

        long daysWithoutSunday = 0;
        int w1 = 0;
        int w2 = 0;
        long actualNumberOfBusinessDays = 0;
        
        Calendar c1 = GregorianCalendar.getInstance();
        c1.setTime(start);
        w1 = c1.get(Calendar.DAY_OF_WEEK);
        c1.add(Calendar.DAY_OF_WEEK, -w1 + 1);

        Calendar c2 = GregorianCalendar.getInstance();
        c2.setTime(end);
        w2 = c2.get(Calendar.DAY_OF_WEEK);
        c2.add(Calendar.DAY_OF_WEEK, -w2 + 1);

        //end Saturday to start Saturday 
        long days = (c2.getTimeInMillis() - c1.getTimeInMillis())/(1000*60*60*24);
        
        daysWithoutSunday = days-(days*2/7);

        if (w1 == Calendar.SUNDAY) 
            w1 = Calendar.MONDAY;
        
        if (w2 == Calendar.SUNDAY) 
            w2 = Calendar.MONDAY;
       
       /*
             * Check if the there are dates which are falling in public holidays?
             * Currently handling only Christmas & New Year days.
             */
            long numberOfBusinessDaysWithoutSundayAndSaturday = daysWithoutSunday - w1 + w2;
            actualNumberOfBusinessDays = numberOfBusinessDaysWithoutSundayAndSaturday;

            while (numberOfBusinessDaysWithoutSundayAndSaturday > 0 && start.before(end))
            {
                if (isPublicHoliday(start))
                    actualNumberOfBusinessDays -= 1;
                start = addDay(start);
                numberOfBusinessDaysWithoutSundayAndSaturday -= 1;
            }
            return actualNumberOfBusinessDays;
    }
    public static boolean isPublicHoliday(Date date) 
    {
        Calendar cal = Calendar.getInstance();
        cal.setTime(date);
        int w1 = cal.get(Calendar.DAY_OF_WEEK);
        
        // check if New Year's Day & not falls on a Saturday or Sunday because weekends are already taken care
        if (cal.get(Calendar.MONTH) == Calendar.JANUARY && cal.get(Calendar.DAY_OF_MONTH) == 1 && w1 != Calendar.SUNDAY && w1 != Calendar.SATURDAY) 
            return true;

        // check if Christmas & not falls on a Saturday or Sunday because weekends are already taken care
        if (cal.get(Calendar.MONTH) == Calendar.DECEMBER && cal.get(Calendar.DAY_OF_MONTH) == 25 && w1 != Calendar.SUNDAY && w1 != Calendar.SATURDAY) 
            return true;
        return false;

    }
    private static Date addDay(Date date)
    {
        Calendar cal = Calendar.getInstance();
        cal.setTime (date);
        cal.add (Calendar.DATE, 1);
        return cal.getTime();
     }