class Hex {

    public static String u8(long v) {
        char[] result = new char[16];
        for (int i = 0; i < 16; i++) {
            result[15 - i] = Character.forDigit((int) v & 0x0f, 16);
            v >>= 4;
        }

        return new String(result);
    }

    private  Hex();

}