Open an objectoutputstream and printwriter on socket

Question

I have the following code:
public void openConnection(String ipAddress) throws ConnectException{
try{
      client = new Socket(ipAddress, 2000);
     out = new PrintWriter(client.getOutputStream(), true);
      objectOut = new ObjectOutputStream(client.getOutputStream());
     in = new ObjectInputStream(client.getInputStream());
     catch(ConnectException e){
     //there is no securityservice on the other side
     throw new ConnectException();}
     catch(Exception e){
               System.out.println("Error : " +e);
* Method that sends a list of constraints to the peer service
* @param: SecurityConstraintList list: the list of constraints that is being sent to the peer
* @param: String origin: the IP address of the sender, the peer uses this to save the list
public void sendConstraints(SecurityConstraintList list, String origin){
try{     out.println(origin);
     out.println("list");
     out.flush();
     objectOut.writeObject(list);
     objectOut.flush();
     in.close();
     objectOut.close();
     out.close();
catch(Exception e){
     System.out.println("Error : "+e.getMessage());
     }The problem is situated in the part where I first print a line to the printwriter and after an object to the objectoutputstream. On the server i get an exception, being OptionalDataException.
I don't get what the problem is. The exception is thrown when he reads information that he didn't expected, but i don't see how this is possible? Part of the code on the serverside is:
else{
     if( inputLine.equals("list") ){
     //it is a securityconstraintlist that is sent
     SecurityConstraintList list;
     list = (SecurityConstraintList)inObject.readObject();
     System.out.println("Saving list");
     AppliedConstraints con = new AppliedConstraints(origin,list);
FileOutputStream fileOutputStream = new FileOutputStream(listFile);
ObjectOutputStream objectOut = new ObjectOutputStream(fileOutputStream);     objectOut.writeObject(con);
     objectOut.flush();                    
     objectOut.close();
     fileOutputStream.close();
     }Is it not possible to open an objectoutputstream and printwriter on the same outputstream? If so, is there an (easy) way to work around this?
Any help would be greatly appreciated.

Answer 1

Not sure what you mean by this 'reading those line
terminators' ? Could you clarify?In your code I see a 'out.println("list");' statement. This sends the following character over your socket -- 'l', 'i', 's', 't', '\r', '\n', where the last characters denote a carriage return and a new line character respectively. Suppose the receiving en of the socket happens to be a Mac, where a line terminator is implemented as a single '\r'. This leaves the following '\n' character unread and ready to be read by the ObjectInputStream, which, obviously, doesn't know how to handle primitive data like this (hence the OptionalDataException).
Like I wrote before -- read those individual bytes and see what really is transmitted over that socket; there must be some spurious bytes in there ...
kind regards,
Jos