question: public RegexFileFilter ( String pattern , IOCase caseSensitivity ) { if ( pattern == null ) { throw new IllegalArgumentException ( "Pattern is missing" ) ; } int flags = 0 ; if ( caseSensitivity != null && ! caseSensitivity . isCaseSensitive ( ) ) { flags = Pattern . CASE_INSENSITIVE ; } this . pattern = Pattern . compile ( pattern , flags ) ; }
target:  Construct a new regular expression filter with the specified flags case sensitivity.