/**
     * Return the extension portion of the file's name .
     *
     * @see #getExtension
     */
    public static String getExtension(File f) {
        return (f != null) ? getExtension(f.getName()) : "";
    }

    public static String getExtension(String filename) {
        return getExtension(filename, "");
    }

        public static String getExtension(String filename) {
        return getExtension(filename, "");
    }

    public static String getExtension(String filename, String defExt) {
        if ((filename != null) && (filename.length() > 0)) {
            int i = filename.lastIndexOf('.');

            if ((i >-1) && (i < (filename.length() - 1))) {
                return filename.substring(i + 1);
            }
        }
        return defExt;
    }

    public static String trimExtension(String filename) {
        if ((filename != null) && (filename.length() > 0)) {
            int i = filename.lastIndexOf('.');
            if ((i >-1) && (i < (filename.length()))) {
                return filename.substring(0, i);
            }
        }
        return filename;
    }