Re: Serialization of empty vector over a socket

[Mark Wielaard <mark at klomp dot org>]

Hi,

On Fri, 2002-07-19 at 23:51, Robertson, Jason V wrote:
> I've got a simple client-server test case where the server listens on a
> socket, accepts a connection, reads in an object, and prints the object's
> toString() representation.  The client simply opens a port to the server,
> and sends a 'new Vector()'.  The problem is, the server gets a
> NullPointerException in the deserialization process when I compile with gcj
> (from GCC 3.1, Linux).
>  
> I tried debugging a little, but I'm not sure if serialization is broken on
> the client, or deserialization on the server.  Here's the output I get on
> the server-side, followed by the code.  Any ideas?

It seems that our serialization implementation is broken :{
I made a simplified example program from the code you provided
(attached). I tried debugging it a bit and I am not sure where the
NullPointerException comes from. When I link with -static (which gives
nicer stack traces when libgcj is compiled with debugging symbols) then
I get a java.lang.RuntimeException: The SHA algorithm was not found to
use in computing the Serial Version UID for class [Ljava.lang.Object;

I am investigating this further.

Cheers,

Mark
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.IOException;
import java.util.Vector;

public class SerVector
{
	public static void main(String[] args)
	{
	  try
	    {
		Vector v = new Vector();
		System.out.println(v);

		// Turn Vector object into serialized byte array.
                ByteArrayOutputStream out = new ByteArrayOutputStream();
                ObjectOutputStream oos = new ObjectOutputStream(out);
		oos.writeObject(v);
		oos.close();
		out.close();
		byte[] array = out.toByteArray();

		// Turn serialized byte array into Vector object.
		ByteArrayInputStream in = new ByteArrayInputStream(array);
                ObjectInputStream ois = new ObjectInputStream(in);
		Vector inObject = (Vector) ois.readObject();

		System.out.println(inObject);
	     }
	  catch(IOException ioe)
	    {
	      ioe.printStackTrace();
	    }
	  catch(ClassNotFoundException cnfe)
	    {
	      cnfe.printStackTrace();
	    }
	}
}