Chatroom log in with no 3rd party libraries
You have a number of missing links in your code, which makes a review hard to do.

Your ServerSocket code at first glance looks OK, but it is actually broken.


    this.running = true;
    ServerSocket ss = new ServerSocket(1000);
    while (this.running) {
        this.threadPool.execute(new InfoGrabber(ss.accept()));
    }



You don't have a declaration for running. If it is a volatile boolean, then it will probably work. If it is not volatile, it'll possibly never work, depending on the setup. I would never recommend the use of volatile, though, so I would recommend an AtomicBoolean. Still, even with an atomic boolean, you may never exit your server loop because it only checks to see if it should stop after it has accepted a connection. The code will sit waiting on the accept() until something happens, even if the running is false. You need a different mechanism, or timeouts, on your code.

The actual socket you get is also badly handled. You create a thread to run the socket on, and you create an ObjectInputStream on the socket. This is OK, but you then schedule that on a thread which exits quickly... the ClientClass instance is registered on to the clientManager, but then no thread appears to be listening for more input from the client? Additionally, nothing has told the client that it is connected.

This code appears to be pretty new, and incomplete.