Stops when opening ObjectInputStream

[Norberhuis]

Hello,

My server stops after a client is connected, a socket is opened and when its about to open a ObjectInputStream. I checked it with short messages to the console that it just stalls before doing that. Here is the bit of code that it stops:

	public void listen(){
		try{
			server = new ServerSocket(4321);
			System.out.println(server.getInetAddress());
		}
		catch(IOException e){
			System.out.println(e);
		}
		while(true){
			listensocket();
		}
	}
	
	
	public void listensocket(){
		//Server accepts client
		try{
			clientsocket = server.accept();
		}
		catch(IOException e){
			System.out.println("Port not accepter: 4321");
			System.exit(-1);
		}
		//Server begins to receive and gets ready to send
		try{
			//the program stops here
			input =  new ObjectInputStream(clientsocket.getInputStream());
						output = new ObjectOutputStream(clientsocket.getOutputStream());
						
		}

[neilcoffey]

Silly question, but are you actually [i]sending[i] anythiing to the server from the client?

When you create an ObjectInputStream, the constructor will not return until it has read the object header stream. So over a network, if you have an ObjectInputStream at one end sitting waiting for the header, but no corresponding ObjectOutputStream ever actually sends it that header from the other end of the connection, then your server will hang (or rather, the listening thread will hang) until the socket times out.

[Norberhuis]

A totally legitimate question. Here is the code the client uses to send to the server:

public Object send(Object aanroep){
		Object antwoord = null;
		try {
			socket = new Socket(SERVER, POORT);
			input = new ObjectInputStream(socket.getInputStream());
			output = new ObjectOutputStream(socket.getOutputStream());
			output.writeObject(aanroep);
			antwoord = input.readObject();
			socket.close();
		}

I hope this helps to clarify the problem and I would like to thank you for your time.

[neilcoffey]

OK, what you've got is a kind of "remote deadlock". The ObjectInputStream on the client is waiting for the object stream from the server before proceeding, but the server isn't going to send that, because its ObjectInputStream is waiting for the header from the client before proceeding...

[Norberhuis]

Thank you very much. I got it fixed by swapping the streams and making sure the object is first send.