class HexString {

    public static String toHexString(byte[] bytes) {
        int i;
        String ret = "";
        String tmp;
        for(i=0; i< bytes.length; i++) {
            if(i> 0)
                ret += ":";
            tmp = Integer.toHexString(U8.f(bytes[i]));
            if (tmp.length() == 1)
                ret += "0";
            ret += tmp; 
        }
        return ret;
    }

}