List files by regex - empty directory

Script

File temp = File.createTempFile("taverna", ".dir");
temp.delete();
temp.mkdir();
temp.deleteOnExit();
directoryPath = temp.getCanonicalPath();

Script

class FileRegexFilter implements FileFilter {

	public FileRegexFilter(String regex) {
		this.regex = regex;
	}

	public boolean accept(File file) {
		return file.getName().matches(regex);
	}

	String regex = null;
}

if (regex == void || regex.equals("")) {
	throw new RuntimeException(
			"The 'regex' parameter cannot be null.  Please enter a valid file extension.");
}

if (directory == void || directory.equals("")) {
	throw new RuntimeException(
			"The 'directory' parameter cannot be null.  Please enter a valid file directory.");
}

File dirObj = new File(directory);

if (!dirObj.exists()) {
	throw new RuntimeException("The 'directory' parameter specified:" + directory
			+ "does not exist.  Please enter a valid file directory.");
}

File[] fileObjList = dirObj.listFiles(new FileRegexFilter(regex));
List filelist = new ArrayList();
for (int i = 0; i < fileObjList.length; i++) {
	filelist.add(fileObjList[i].getAbsolutePath());
}

Value