More file renaming, this time in Java. Demonstrates why you wouldn't really want to do it this way. Sorry about the wacky formatting, I was trying to reduce the line length so it fits on the page better.

import java.io.*;

public class Rename {

    public static void main(String[] args) {
	File directory =
	    new File(System.getProperty("user.dir"));
	String[] textFileNames =
	    directory.list(new FilenameFilter() {
		    public boolean accept(File dir, String name) {
			return name.endsWith(".txt");
		    }
		});
	for (int i = 0; i < textFileNames.length; ++i) {
	    File oldFile =
		new File(textFileNames[i]);
	    File newFile =
		new File(textFileNames[i].
			 substring(0,
				   textFileNames[i].length() - 4) +
			 ".xml");
	    oldFile.renameTo(newFile);
	}
    }
}