Java: convert int to InetAddress

Question

I have an int which contains an IP address in network byte order, which I would like to convert to an InetAddress object. I see that there is an InetAddress constructor that takes a byte[], is it necessary to convert the int to a byte[] first, or is there another way?

Answer 1

This should work:

int ipAddress = ....
byte[] bytes = BigInteger.valueOf(ipAddress).toByteArray();
InetAddress address = InetAddress.getByAddress(bytes);

You might have to swap the order of the byte array, I can't figure out if the array will be generated in the correct order.

Answer 2

Not enough reputation to comment on skaffman's answer so I'll add this as a separate answer.

The solution skaffman proposes is correct with one exception. BigInteger.toByteArray() returns a byte array which could have a leading sign bit.

byte[] bytes = bigInteger.toByteArray();

byte[] inetAddressBytes;

// Should be 4 (IPv4) or 16 (IPv6) bytes long
if (bytes.length == 5 || bytes.length == 17) {
    // Remove byte with most significant bit.
    inetAddressBytes = ArrayUtils.remove(bytes, 0);
} else {
    inetAddressBytes = bytes;
}

InetAddress address = InetAddress.getByAddress(inetAddressBytes);

PS above code uses ArrayUtils from Apache Commons Lang.