ClientController.java

package server;

import java.io.Serializable;
import java.net.InetAddress;
import java.rmi.Remote;
import java.rmi.RemoteException;
import java.rmi.registry.LocateRegistry;
import java.rmi.registry.Registry;
import java.rmi.server.UnicastRemoteObject;
import java.util.ArrayList;
import java.util.Observable;
import java.util.Observer;

import client.UpdateController;
import remote.IClientController;
import remote.IUpdateController;

/**
 * Server side implementation of the remote interface.
 * Must extend UnicastRemoteObject, to allow the JVM to create a
 * remote proxy/stub.
 *
 */
public class ClientController extends UnicastRemoteObject implements IClientController, Serializable {

    /**
     * Added
     */
    //private static final long serialVersionUID = 1L;

    private ArrayList<User> userList;

    protected ClientController() throws RemoteException {
        userList = new ArrayList<>();
    }

    @Override
    public String joinServer(String userName, InetAddress ipAddress, String rmiName) throws RemoteException {
        try
        {
            Registry userRMI = LocateRegistry.getRegistry(ipAddress.getHostAddress());
            IUpdateController updateController = (IUpdateController) userRMI.lookup(rmiName);

            User user = new User(userName, ipAddress, rmiName);
            userList.add(user);
            for (User u : userList) {
                if (!userName.equals(u.getUsername())) {
                    u.getUpdateController().updateClient(userName);
                }
            }
            System.out.println("User " + userName + " added successfully");
        }
        catch (Exception e)
        {
            e.printStackTrace();
        }
        return "update successfully";
    }

    @Override
    public ArrayList<String> getUsernameList() throws RemoteException {
        ArrayList<String> usernameList = new ArrayList<>();
        for (User u : userList) {
            usernameList.add(u.getUsername());
        }
        return usernameList;
    }


}