question: public static Date zeroTimeDate ( Date date ) { final GregorianCalendar gregorianCalendar = new GregorianCalendar ( ) ; gregorianCalendar . setTime ( date ) ; gregorianCalendar . set ( Calendar . HOUR_OF_DAY , 0 ) ; gregorianCalendar . set ( Calendar . MINUTE , 0 ) ; gregorianCalendar . set ( Calendar . SECOND , 0 ) ; gregorianCalendar . set ( Calendar . MILLISECOND , 0 ) ; return gregorianCalendar . getTime ( ) ; }
target:  Reset the time of a date