RMI Vector/ArrayList Serialization problem

[Dave Winters]

Hi all,

Im having a problem at the moment trying send a Vector which contains a serialized class objects from my server program to my client. Firstly i retrieve the contents of a file, store them into the serialized class "Reservation", i then add each new Reervation object to a Vector. I the wish to send this Vector to the client so it can print out the list of "Reservation Objects" from my Vector class. It prints out the value null. There seems to be a problem, with adding serialized objects to the Vector class. I thought The Vector class was serializable. There is no problem with the Serialized Reservation class. I can send it to/from the client/server no problem. Any help with this problem would be greatly appreciated.

Thanks,

Dave.

Code:

StringTokenizer tempfilerecords = new StringTokenizer(file.readLine());


while(tempfilerecords.hasMoreElements())
{
templong = tempfilerecords.nextToken();
recid = Long.parseLong(templong);
first = tempfilerecords.nextToken();
last = tempfilerecords.nextToken();
tempres = new Reservation(recid,first,last);
 
reservation.addElement(tempres);
tempfilerecords = new StringTokenizer(file.readLine());
}
        for(int j =0; j<= reservation.size(); j++)
{
     temp = (Reservation)reservation.elementAt(j)
     System.out.println( temp.getRecid() );
}

}
catch(IOException rd){System.out.println(rd.getCause());}
return reservation;

[Andrew: Put code between [code] and [/code] UBB tags]
[ April 22, 2005: Message edited by: Andrew Monkhouse ]

[Andrew Monkhouse]

Hi Dave,

Welcome to JavaRanch and this forum.

You will notice that I have edited your post to put the code between

import java.io.*;
import java.net.*;
import java.util.*;
 
public class SocketClient {
    public static void main(String[] args) throws IOException, InterruptedException {
        Socket socket = new Socket("localhost", 1234);
        ObjectOutputStream out = new ObjectOutputStream(socket.getOutputStream());
        ObjectInputStream in = new ObjectInputStream(socket.getInputStream());
 
        Vector <String>output = new Vector<String>();
        output.add("hello, world");
        output.add("line 2");
        output.add("line 3");
        out.writeObject(output);
        Thread.sleep(1000);
    }
}

Then printing them out at the far end:

import java.io.*;
import java.net.*;
 
public class SocketServer extends Thread {
    public static void main(String[] args)
            throws IOException, SocketException, ClassNotFoundException {
        ServerSocket serverSocket = new ServerSocket(1234);
        Socket socket = serverSocket.accept();
        ObjectOutputStream out
                = new ObjectOutputStream(socket.getOutputStream());
        ObjectInputStream in
                = new ObjectInputStream(socket.getInputStream());
 
        while (true) {
            Object received = in.readObject();
            System.out.println(received);
        }
    }
}

When I run this I get the following output:

C:\Temp>java SocketServer
[hello, world, line 2, line 3]
Exception in thread "main" java.net.SocketException: Connection reset

Note that I am using JDK 1.5 which does some nicer things with displaying contents of Collections, and also allows me to use Generics in my SocketClient.

So starting with that code as a basis, you should be able to see that you can send a Vector containing Serialized Objects through sockets. Perhaps you can create some dummy data to fit into your Reservation instance, and plug it into the code above to see if this is working? Then put in the real data into the Reservation instance and see if it still works, and so on, until you work out where things start to break.

Regards, Andrew