Not in general no.  The client machine itself may not know what its IP address
is.  For instance none of my machines here (which are behind a NATing router)
have any idea how they appear to the rest of the Internet.

If you want the address they have on the local LAN, then that's probably doable
(I can't remember how offhand).  That information may or may not be useful
and/or reliable depending on what you want to do with it.  Note that machines
may have more than one physical network connection, and hence more than one
local IP address.

   -- chris

  You can get the IP Address in the following way:

                 InetAddress addr = InetAddress.getLocalHost();
           // Get IP Address
           byte[] ipAddr = addr.getAddress();

                 // Get hostname
           String hostname = addr.getHostName();
just try it  out.

Nothing wrong with that result, depending on what you're trying to
acheive.

For more choices, iterate over the available NetworkInterfaces and
choose one you like.

/gordon

When you say "client PC", do you mean the PC on which the code is running, or
are you talking about a Socket on a server and wanting the IP address of the
client connected to that socket?

For the former, the way to do that is to iterate over the network interfaces and
get their IP addresses. One of those interfaces will be the "loopback"
interface, which always has the IP address 127.0.0.1.
http://java.sun.com/docs/books/tutorial/networking/nifs/listing.html

For the latter you can get the client address from the socket. Offhand I can't
remember the exact incantation, Socket.getRemoteAddress() ?