You can get all the network interfaces on the machine, via pure Java, using java.net.NetworkInterface.getNetworkInterfaces(). For each of these, you can get a list of java.net.InetAddress, from which you can get an IP address.
Most machines have one adapter with one IP address, but some are more complicated.
I don't think you can get the MAC address with pure Java. What do you want it for?
Betty Rubble? Well, I would go with Betty... but I'd be thinking of Wilma.