question: public static RegularExpression createRegex ( String pattern , String options ) throws ParseException { RegularExpression re = null ; int intOptions = REUtil . parseOptions ( options ) ; synchronized ( REUtil . regexCache ) { int i ; for ( i = 0 ; i < REUtil . CACHESIZE ; i ++ ) { RegularExpression cached = REUtil . regexCache [ i ] ; if ( cached == null ) { i = - 1 ; break ; } if ( cached . equals ( pattern , intOptions ) ) { re = cached ; break ; } } if ( re != null ) { if ( i != 0 ) { System . arraycopy ( REUtil . regexCache , 0 , REUtil . regexCache , 1 , i ) ; REUtil . regexCache [ 0 ] = re ; } } else { re = new RegularExpression ( pattern , options ) ; System . arraycopy ( REUtil . regexCache , 0 , REUtil . regexCache , 1 , REUtil . CACHESIZE - 1 ) ; REUtil . regexCache [ 0 ] = re ; } } return re ; }
target:  Creates a RegularExpression instance. This method caches created instances.