** * This class provides convenient functions to convert hex string to byte array and vice versa.* */public class HexUtil {         private static final String HEX_CHARS = "0123456789abcdef";    private HexUtil() {}            /**     * Converts a byte array to hex string.     *      * @param b -     *            the input byte array     * @return hex string representation of b.     */    public static String toHexString(byte[] b) {        StringBuffer sb = new StringBuffer();        for (int i = 0; i < b.length; i++) {            sb.append(HexUtil.HEX_CHARS.charAt(b[i] >>> 4 & 0x0F));            sb.append(HexUtil.HEX_CHARS.charAt(b[i] & 0x0F));        }        return sb.toString();    }    /**     * Converts a hex string into a byte array.     * @param s -     *            string to be converted     * @return byte array converted from s     */    public static byte[] toByteArray(String s) {        byte[] buf = new byte[s.length() / 2];        int j = 0;        for (int i = 0; i < buf.length; i++) {            buf[i] = (byte) ((Character.digit(s.charAt(j++), 16) << 4) | Character.digit(s.charAt(j++), 16));        }        return buf;    }   }