Error passing a remote object in a rmi function call

Question

Hi,
I've a problem passing an UnicastRemoteObject extended object in a rmi function call. I get the following error
java.lang.IllegalArgumentException: argument type mismatch
I've 2 Remote Objects: GalaxyRegistration and Station. I want to pass a Station Object as argument in a function from GalaxyRegistration. Does anyone know what the problem is?
Here is the code:
public class GalaxyRegistration
extends UnicastRemoteObject
implements GalaxyRegistrationInterface, Galaxy {
     public GalaxyRegistration() throws RemoteException {
     public void add(Station station) throws RemoteException {
          stations.addElement(station);
          System.out.println("Add Station " + station.getName());
public class Station
extends UnicastRemoteObject
implements StationInterface {
     SystemInfo system;
     public Station(String name, String description, Coordinate position, Profile profile)
throws RemoteException {
          system = new SystemInfo(name, description, position, profile);
public class StationServer {
     Station station;
     public void run() {
          // create new Station
          System.out.println("Create new Station:");
          // register and bind new station
          try     {
               station = new Station(name, descr, location, profile);
               System.out.println("Station created ...");
               GalaxyRegistrationInterface registry =
                         (GalaxyRegistrationInterface)
                         Naming.lookup
("//localhost/GalaxyRegistration");
               System.out.println("Registry looked up ...");               
               // >>>>>>>> NEXT LINE IS THE ERROR LINE <<<<<<<<<<<<<<     
               registry.add(station);
          } catch(Exception e) {
               System.out.println(e);
}

Answer 1

regardless of any other problems in your code, neither of the objects which you are subclassing from UnicastRemoteObject call the superclass constructor, which is a pretty basic flaw - in this case, it will lead to neither of these objects being exported properly.