class DateUtils {

    public static List<DayOfWeek> fromCalendarDaysOfWeekToISO(final List<Integer> calendarDaysOfWeek) {

        if (calendarDaysOfWeek != null) {
            final List<DayOfWeek> iso = new ArrayList<>(calendarDaysOfWeek.size());
            for (final Integer dow : calendarDaysOfWeek) {
                switch (dow) {
                    case Calendar.MONDAY:
                        iso.add(DayOfWeek.MONDAY);
                        break;
                    case Calendar.TUESDAY:
                        iso.add(DayOfWeek.TUESDAY);
                        break;
                    case Calendar.WEDNESDAY:
                        iso.add(DayOfWeek.WEDNESDAY);
                        break;
                    case Calendar.THURSDAY:
                        iso.add(DayOfWeek.THURSDAY);
                        break;
                    case Calendar.FRIDAY:
                        iso.add(DayOfWeek.FRIDAY);
                        break;
                    case Calendar.SATURDAY:
                        iso.add(DayOfWeek.SATURDAY);
                        break;
                    case Calendar.SUNDAY:
                        iso.add(DayOfWeek.SUNDAY);
                        break;
                }
            }
            return iso;
        }
        return new ArrayList<>(0);
    }

    private  DateUtils();

}