Java networking basics - JavaTech: An Introduction to Scientific and Technical Computing with Java - page 424

The applet LocalAddress displays the local host and IP address. Note
that the SecurityManager in the browser JVM may block access to this
information. You can try it in the appletviewer tool or run it as an
application.
import java.applet.*;
import java.awt.*;
import java.net.*;
/** Show how InetAddress can provide the local
*IPaddress. **/
public class LocalAddress extends Applet
{
String fMessage ="";
/**
* Create an instance of InetAddress for the
* local host and display the local IP address.
**/
public void init () {
try {
InetAddress local - Address =
InetAddress.getLocalHost ();
fMessage ="Local IP address ="
+ local - Address.toString ();
}
catch (UnknownHostException e) {
fMessage ="Unable to obtain local IP address";
}
System.out.println (fMessage);
} // init
/** Paint IP info in Applet window. **/
public void paint (Graphics g) {
g.drawString (fMessage, 20, 20);
} // paint
/** Print out the local address in app mode. **/
public static void main (String [] args) {
LocalAddress applet = new LocalAddress ();
applet.init ();
} // main
} // class LocalAddress