RMI and ArrayLists

[trispad]

Does anyone know how to get at the data within and ArrayList using RMI. I have looked at the source code for ArrayList and the Object Array elementData is a transient variable. Therefor when elementData is not serialized when a call for it is made through RMI. I have tried using:

private final ObjectStreamField serialPersistentFields = new
           ObjectStreamField( "elementData", Object.class );

to get around the fact that elementData is transient. But then I run into the problem that the Object class is not serializable. I have been searching for some time now and have not found an answer or a workaround. Does anyone here know a solution?

Thanks much
-trispad

[trispad]

Does any one know a forum that I can try??

Thanks

[horace1]

have a look at this simple example which uses RMI to pass an ArrayList to a server and get it back

The interface

// RMIarrayList.java  - the interface

import java.util.*;

import java.rmi.*;                 
public interface RMIarrayList extends Remote
{
  public ArrayList passArrayList(ArrayList a) throws RemoteException;
}

the server

// RMIarrayListImpl.java

import java.rmi.*;
import java.net.*;
import java.util.*;

public class RMIarrayListImpl extends java.rmi.server.UnicastRemoteObject
       implements RMIarrayList
{

  public RMIarrayListImpl() throws RemoteException
  {
    super();
  }

  // receive an array list, print it, add an element and return it
  public ArrayList passArrayList(ArrayList a) throws RemoteException
  {
    System.out.println(" RMI ArrayList server received array list " + a);
    a.add( "goodbye" );      
    return a;
  }

  public static void main(String args[])
  {
    try
    {
      // bind to RMI server
      RMIarrayListImpl h = new RMIarrayListImpl();
      Naming.rebind("rmi://localhost/RMIarrayList", h);
      System.out.println("RMI ArrayList server ready");
    }
    catch (RemoteException re)
    {
      System.out.println("Remote Exception " + re);
    }
    catch (Exception e)
    {
      System.out.println(" Exception " + e);
    }
  }
}

the client

// RMIarrayListClient.java

import java.rmi.*;
import java.util.*;

public class RMIarrayListClient
{
  public static void main(String args[])
  {
    String host="localhost";    // RMI host name
    
    /* System.setSecurityManager(new RMISecurityManager()); */
    try
    {
      // lookup RMI server
      RMIarrayList h = (RMIarrayList) Naming.lookup("rmi://"+host+"/RMIarrayList");
      // create ArrayList and add some elements
      ArrayList<String>  v = new ArrayList<String>();
      v.add( "able" );
      v.add( "baker" );
      v.add( "charlie" );
      v.add( "delta" );      
      System.out.println("RMIarrayListClient sending: " +v);
      // send array list to server and print array list received back
      ArrayList a = h.passArrayList(v);
      System.out.println("RMIarrayListClient  received: " +a);
    }
    catch (Exception e)
    {
      System.out.println("Exception in main " + e);
    }
  }
}

instructions on running the RMI programs

Distributed Systems RMI
First the simple RMIarrayList. 
    This consists of 3 files RMIarrayList.java , RMIarrayListClient.java   and RMIarrayListImpl.java . 
    RMIarrayList.java is the interface file, RMIarrayListImpl.java is the server. 
    Compile these files (i.e. javac file.java) 
    Then create the stub files with :- 
        rmic RMIarrayListImpl 
    If all has gone well you should have 2 stub files 
        RMIarrayListImpl_Stub.class 
        RMIarrayListImpl_Skel.class 
    You are now ready to run the application 
First start the registry - 
        rmiregistry 
In another window start the server with  java RMIarrayListImpl 
It  should print the message 
RMI ArrayList server ready

In a third window start the client with java RMIarrayListClient 
It should print 
RMIarrayListClient sending: [able, baker, charlie, delta]
RMIarrayListClient  received: [able, baker, charlie, delta, goodbye] 
and the server should print
RMI ArrayList server received array list [able, baker, charlie, delta] 
Stop the registry and the server. 
There is also a useful tutorial on the official site for Getting Started with RMI