The InetAddress is Java's representation of an IP address. Instances of this class are used together with UDP DatagramSockets and normal Socket's and ServerSocket's.
Creating an InetAddress Instance
InetAddress has no public contructor, so you must obtain instances via a set of static methods.
Here is how to get the InetAddress instance for a domain name:
InetAddress address = InetAddress.getByName("jenkov.com");
And here is how to get the InetAddress matching a String representation of an IP address:
InetAddress address = InetAddress.getByName("78.46.84.171");
And, here is how to obtain the IP address of the localhost (the computer the program is running on):
InetAddress address = InetAddress.getLocalHost();
Additional InetAddress Methods
The InetAddress class has a lot of additional methods you can use. For instance, you can obtain the IP address as a byte array by calling getAddress() etc. To learn more about these methods, it is easier to read the JavaDoc for the InetAddress class though.