public long getFirstMillisecond(Calendar calendar) {
        int year = this.day.getYear();
        int month = this.day.getMonth() - 1;
        int day = this.day.getDayOfMonth();
        calendar.clear();
        calendar.set(year, month, day, this.hour, this.minute, this.second);
        calendar.set(Calendar.MILLISECOND, 0);
        //return calendar.getTimeInMillis();  // this won't work for JDK 1.3
        return calendar.getTime().getTime();