Can anybody help me to understand this RMI registry service code?

Question

RMI is so difficult to me. please let me know following code what it means.
If this class is instantiated with 50000 port number,
Does RMI Registry Service get started with 50000 port number in place of rmiregistry commands?
And I don't have to execute rmiregistry command?
thanks in advance.
import java.rmi.AccessException;
import java.rmi.AlreadyBoundException;
import java.rmi.NotBoundException;
import java.rmi.Remote;
import java.rmi.RemoteException;
import java.rmi.registry.Registry;
import java.rmi.server.ObjID;
import java.rmi.server.RemoteServer;
import java.util.Enumeration;
import java.util.Hashtable;
import sun.rmi.server.UnicastServerRef;
import sun.rmi.transport.LiveRef;
* Registry implementation.
* @version 1.0
public class RegistryImpl extends RemoteServer implements Registry {
     private static final long serialVersionUID = -7162736590129110751;
     private Hashtable bindings;
    private static ObjID id = new ObjID(0);
     * @param i port number
     * @throws RemoteException
    public RegistryImpl(int i) throws RemoteException {
        bindings = new Hashtable(101);
        LiveRef liveref = new LiveRef(id, i);
        setup(new UnicastServerRef(liveref));
    private void setup(UnicastServerRef unicastserverref) throws RemoteException {
        super.ref = unicastserverref;
        unicastserverref.exportObject(this, null, true);
     * Lookup a remote object.
     * @param name Name of the remote object.
     * @return Remote object of the specified name.
    public Remote lookup(String name) throws RemoteException, NotBoundException {
//        Logger.debug("NamingService", "lookup: " + name);
        Remote obj;
        synchronized(bindings) {
            obj = (Remote)bindings.get(name);
            if(obj == null)
                throw new NotBoundException(name);
        return obj;
     * Binds the specified name to a remote object.
     * @param name A URL-formatted name for the remote object.
     * @param obj A reference for the remote object (usually a stub).
    public void bind(String name, Remote obj) throws RemoteException, AlreadyBoundException, AccessException {
//        Logger.debug("NamingService", "bind: " + name);
        checkAccess("Registry.bind");
        synchronized(bindings) {
            if(bindings.containsKey(name))
                throw new AlreadyBoundException(name);
            bindings.put(name, obj);
     * Destroys the binding for the specified name that is associated with a remote object.
     * @param name A URL-formatted name for the remote object.
    public void unbind(String name) throws RemoteException, NotBoundException, AccessException {
//        Logger.debug("NamingService", "unbind: " + name);
        checkAccess("Registry.unbind");
        synchronized(bindings) {
            if(!bindings.containsKey(name))
                throw new NotBoundException(name);
            bindings.remove(name);
     * Rebinds the specified name to a new remote object. Any existing binding
     * for the name is replaced.
     * @param name A URL-formatted name for the remote object.
     * @param obj A reference for the remote object (usually a stub).
    public void rebind(String name, Remote obj) throws RemoteException, AccessException {
//        Logger.debug("NamingService", "rebind: " + name);
        checkAccess("Registry.rebind");
        bindings.put(name, obj);
     * Returns an array of the names bound in the registry.
     * @return An array of the names bound in the registry.
    public String[] list() throws RemoteException {
        String[] names;
        synchronized(bindings) {
            int i = bindings.size();
            names = new String;
Enumeration e = bindings.keys();
while(--i >= 0)
names[i] = (String)e.nextElement();
return names;
* TO-DO
public static void checkAccess(String s) throws AccessException {
// check if s is in the list of agents.
if(true)
else
throw new AccessException("");
public static ObjID getID() {
return id;

Answer 1

You don't have any need to understand this code. The complication is due to the registry needing a fixed objectID.
You just need to know the methods of java.rmi.registry.LocateRegistry class. This allows you to start an RMI Registry inside your JVM and give it any TCP port number you like.