Question

I have a byte[5] array which represents a decimal number when printed as a hex string. Two digits can be stored in one byte, the hex characters are not used.
E.g.

[0x11,0x45,0x34,0x31,0x21] -> 1145343121.

Is there a more efficient way in Java (some bitshifting magic maybe) to do the conversion to a decimal number other than

long result = Long.parseLong(byteToHexString(bytes[]));?

An efficient conversion vice versa would also be interesting…

Answer 1

Here you go, trick is to nibble a nibble at a time !

    byte[] buf = { 0x11, 0x45, 0x34, 0x31, 0x21 };
    long result = 0;
    for (int i = 0; i < buf.length; i++) {
        result = result * 100 + (buf[i] >> 4 & 0XF) * 10 + (buf[i] & 0XF);
    }
    System.out.println(result);

Output

1145343121