question: public static Date daysBeforeNow ( int numDays ) { if ( numDays <= 0 ) { throw new IllegalArgumentException ( ) ; } final Calendar cal = new GregorianCalendar ( ) ; cal . setTime ( new Date ( ) ) ; cal . add ( Calendar . DAY_OF_YEAR , - numDays ) ; return cal . getTime ( ) ; }
target:  Method to return a Date instance which is exactly numDays days before the current point in time. 