public static Calendar startOfHour(Calendar origin) {
        Calendar cal = (Calendar) origin.clone();
        cal.set(Calendar.MILLISECOND, 0);
        cal.set(Calendar.SECOND, 0);
        cal.set(Calendar.MINUTE, 0);
        return cal;
    }
public static Calendar startOfHour ( Calendar origin ) { Calendar cal = ( Calendar ) origin . clone ( ) ; cal . set ( Calendar . MILLISECOND , 0 ) ; cal . set ( Calendar . SECOND , 0 ) ; cal . set ( Calendar . MINUTE , 0 ) ; return cal ; }
Calculate the start-of-hour point of a supplied {@link Calendar}.

<p>
The returned {@link Calendar} has its fields unsynced. Note: if {@code origin} has
unsynced field, it may cause side-effect.
</p>

@param origin
@return