question: static public Timestamp addDays ( Timestamp day , int offset ) { if ( day == null ) day = new Timestamp ( System . currentTimeMillis ( ) ) ; GregorianCalendar cal = new GregorianCalendar ( ) ; cal . setTime ( day ) ; cal . set ( Calendar . HOUR_OF_DAY , 0 ) ; cal . set ( Calendar . MINUTE , 0 ) ; cal . set ( Calendar . SECOND , 0 ) ; cal . set ( Calendar . MILLISECOND , 0 ) ; if ( offset != 0 ) cal . add ( Calendar . DAY_OF_YEAR , offset ) ; return new Timestamp ( cal . getTimeInMillis ( ) ) ; }
target:  Return Day + offset (truncates)