private static void catalogArchive(final File jarfile, final Collection<String> files) {

        try {

            final JarFile j = new JarFile(jarfile);
            final Enumeration<JarEntry> e = j.entries();
            while (e.hasMoreElements()) {
                final JarEntry entry = e.nextElement();
                if (!entry.isDirectory()) {
                    files.add(entry.getName());
                }
            }

        } catch (IOException x) {
            System.err.println(x.toString());
        }

    }