Problem with regex being used to filter filenames ...

Question

I wrote a simple FilenameFilter that takes a regular expression (String) in it's constructor. It uses that regex to determine which files to return when a directory is read using the listFiles(FilenameFilter) syntax.
The problem I'm having is probably with my regex. If I use a regex like ".*[.]xml", the filter appears to work as I would expect: I get only files that end in XML.
If on the other hand I try to do a little more complex regex to get all the files that don't end in ".xml", it seems to match everything.
In my code, I am doing the following:
                // Only deal with files that don't end in XML
                fileList = dir.listFiles(new RegexFilenameFilter(".*[.](?!xml).*$"));Where I'm using the regex ".*[.](?!xml).*$", which should match any string that doesn't end with .xml.
My RegexFilenameFilter follows:
* RegexFilenameFilter.java
* Created on May 26, 2006, 10:27 AM
* To change this template, choose Tools | Template Manager
* and open the template in the editor.
package com.jmmdhs.util;
import java.io.File;
import java.io.FilenameFilter;
import java.util.regex.Pattern;
import org.apache.log4j.Logger;
* Regular Expression FilenameFilter - allows filtering directory by regex.
public class RegexFilenameFilter implements FilenameFilter {
    private static final Logger logger = Logger.getLogger(RegexFilenameFilter.class);
    private String patternString = null;
    private Pattern regexPattern; 
     * Constructor that takes a String containing the regex for matching
     * @param regexString Regular expression string.
    public RegexFilenameFilter(String regexString) {
        logger.debug("Constructing RegexFilenameFilter with expression '" + regexString + "'");
        patternString = regexString;
        regexPattern = Pattern.compile(patternString);
     * Method returns true if the pattern matches.
     * @param directory Directory to match
     * @param fileName Name of the file to match
     * @return Boolean indicating match.
    public boolean accept(File directory, String fileName) {
        return regexPattern.matcher(fileName).matches();     
}

Answer 1

public static void main(String args[])
        ArrayList<String> al = new ArrayList<String>();
        al.add( "sfsd.txt" );
        al.add( "dfde.doc" );
        al.add( "sfsd.xml" );
        al.add( "sfsd.txt" );
        al.add( "win.xml" );
        Iterator i = al.iterator();
        while ( i.hasNext() )
            String s = (String) i.next();
            if ( s.endsWith( ".xml" ) )
                System.out.println( s );
    }