class DateUtil {

    public static Date getStartOfDate(final Date date) {
        if (date == null) {
            return null;
        }

        Calendar cal = GregorianCalendar.getInstance();
        cal.setTime(date);
        cal.set(Calendar.HOUR_OF_DAY, 0);
        cal.set(Calendar.MINUTE, 0);
        cal.set(Calendar.SECOND, 0);
        cal.set(Calendar.MILLISECOND, 0);
        return cal.getTime();
    }

}