Problem with regex being used to filter filenames ...
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.
*/
publicclass RegexFilenameFilterimplements FilenameFilter{
privatestaticfinal 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.
*/
publicboolean accept(File directory, String fileName){
return regexPattern.matcher(fileName).matches();
}
}
