This is my javax.swing.filechooser.FileFilter implementation (for the JFileChooser):

FileFilter fileFilter = new FileFilter()
{
	@Override
	public boolean accept(File file)
	{
		return file.getAbsolutePath().endsWith(".xml") || file.isDirectory();
	}

	@Override
	public String getDescription()
	{
		return "xml settings files";
	}
};

It accepts .xml files, but allows browsing through directories