code: public static int aton(final InetAddress ip)
  	{
  		if (ip == null)
  		{
  			throw new Error("the result of aton(null) is undefined");
  		}
  		if (ip instanceof Inet4Address)
  		{
  			return aton((Inet4Address) ip);
  		}
  		else
  		{
  			throw new Error("int aton(InetAddress) does not function for " + ip.getClass());
  		}
  	}
docs: Converts an InetAddress to a numeric address <strong>only</strong> in the case of IPv4 (Inet4Address) addresses. Other
  addresses will result in an Error being thrown
  
  @param ip
  
  @return