CODEWITHSUNDEEP
javamultithreadingsockets
DNB5brims
DNB5brims

Reputation: 30568

Why I can't use two threads holding the same socket in Java?

Here is the code:

TaskA a = new TaskA(this.serverSocket, this.socket);
a.assignConfig(this.config);
this.threada = new Thread(a);
this.threada.start();

TaskB b = new TaskB(this.serverSocket, this.socket);
b.assignConfig(this.config);
this.threadb = new Thread(b);
this.threadb.start();

In TaskA, this class work like that:

        if (this.serversocket == null) {
            this.serversocket = new ServerSocket(this.config.getI_respondPort());
        }

        if (this.serversocket != null) {
            System.out
                    .println("this.serversocket " + this.serversocket);
        }

        this.serversocket.setSoTimeout((int) this.config
                .getL_respondSocketInterval());

        while (this.is_keepRun()) {
                System.out.println("Keep Listening");

                Thread.sleep(this.config.getL_heartBeatInterval());
        }

And the TaskB is like this:

    while (this.is_keepRun()) {

            if (this.serversocket != null) {
                System.out.println("waiting input");

                this.socket = this.serversocket.accept();

                System.out.println("Connection received from "
                        + this.socket.getInetAddress().getHostName());
            }

    }

I assign the same serverSocket and socket via their own constructor, but when the socket got the connection, TaskA can do the serversocket.accept, but the TaskB's serversocket is always null, wt did I do wrong? Thanks.

Upvotes: 1

Views: 122

Answers (1)

Joelio
Joelio

Reputation: 4691

ServerSockets are looking for new socket connections, and block on a given port. If you want multiple server sockets use multiple ports. If you want multiple threads on various sockets, then use one server socket, and have a thread to do the work once its created. The accept is just waiting for one to be created, see here for a good basic intro to sockets: http://docs.oracle.com/javase/tutorial/networking/sockets/clientServer.html

Upvotes: 2

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