question: public static int indexOfLastSeparator ( String filename ) { if ( filename == null ) return - 1 ; int lastUnixPos = filename . lastIndexOf ( UNIX_SEPARATOR ) ; int lastWindowsPos = filename . lastIndexOf ( WINDOWS_SEPARATOR ) ; return Math . max ( lastUnixPos , lastWindowsPos ) ; }
target:  Returns the index of the last directory separator character. <p> This method will handle a file in either Unix or Windows format. The position of the last forward or backslash is returned. <p> The output will be the same irrespective of the machine that the code is running on.