When using Java’s Remote Method Invocation (RMI), you may have defined a server class that extends java.rmi.server.UnicastRemoteObject. Extending UnicastRemoteObject makes your class capable of handling incoming calls, and is acceptable in many cases. However, you sometimes will want to extend a different class and still retain the ability to handle incoming RMI calls. Fortunately, there’s a simple solution to this problem. The UnicastRemoteObject constructor makes the object accessible by calling the static exportObject() method, and because this method is public, your class can call it directly. In this code, an instance of RMIServer is created, exported, and added to the registry. Although it does not extend UnicastRemoteObject, it can be accessed through registry lookup and called using RMI.

 import java.rmi.*;import java.rmi.server.*;public class RMIServer extends Object implements RMIInterface {	public static void main(String[] args) throws Exception {		RMIServer s = new RMIServer();		UnicastRemoteObject.exportObject(s);		Naming.rebind("MyServer", s);	}  //  public static void main()}  //  public class RMIServer extends Object