Going from 127.0.0.1 to 2130706433, and back again

String to int:

int pack(byte[] bytes) {
  int val = 0;
  for (int i = 0; i < bytes.length; i++) {
    val <<= 8;
    val |= bytes[i] & 0xff;
  }
  return val;
}

pack(InetAddress.getByName(dottedString).getAddress());

Int to string:

byte[] unpack(int bytes) {
  return new byte[] {
    (byte)((bytes >>> 24) & 0xff),
    (byte)((bytes >>> 16) & 0xff),
    (byte)((bytes >>>  8) & 0xff),
    (byte)((bytes       ) & 0xff)
  };
}


InetAddress.getByAddress(unpack(packedBytes)).getHostAddress()

You can also use the Google Guava InetAddress Class

String ip = "192.168.0.1";
InetAddress addr = InetAddresses.forString(ip);
// Convert to int
int address = InetAddresses.coerceToInteger(addr);
// Back to str 
String addressStr = InetAddresses.fromInteger(address));