java object streams

Question

I'm trying to create a server in java which will maintain up to 4 connections simultaneously. I thought that holding the relevant information in an array would serve my purpose, well, but I'm having some trouble.

Here is the class I've created:

import java.net.*;
import java.io.*;
public class tcpConnects{
private ObjectInputStream input;
private ObjectOutputStream output;
private int player;
public tcpConnects(int playerNumber, Socket connect) {
 // TODO Auto-generated method stub
 try{
 System.out.println("create InputStream");
 input= new ObjectInputStream(connect.getInputStream());
 System.out.println("create OutputStream");
 output= new ObjectOutputStream(connect.getOutputStream());
 System.out.println("streams created");
 //sendData("Welcome!");
 player=playerNumber;
 }catch (IOException ioException){
 ioException.printStackTrace();
 }
 }
 public ObjectInputStream getInput(){
 return input;
 }
 public void setInput(ObjectInputStream in){
 input=in;
 }
 public ObjectOutputStream getOutput(){
 return output;
 }
 public void setOutput(ObjectOutputStream out){
 output=out;
 }
 public int getPlayer(){
 return player;
 }
 public void sendData(String data){
 try{
 output.writeObject(data);
 output.flush();
 }catch (IOException ioException){
 ioException.printStackTrace();
 }
 }
}

anyway, when I send a socket into the class, it gets to the stage of creating the input stream, but then the stream is never actually created. The syntax appears to be correct, so I can only assume that there is some form of logic error which I am not aware of. Any help in deciphering why this class will not create an input or output stream would be greatly appreciated.

Thanks,

Answer 1

Create the ObjectOutputStream before the ObjectInputStream, at both ends. The constructor of ObjectOutputStream writes a header to the stream that the constructor of ObjectInputStream reads, so if you create the ObjectInputStreams first you get a deadlock.

• Rolan: Thanks, EJP, you've been a great help! Creating the output stream first on both ends worked perfectly!