Server Class

import java.io.File;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.net.ServerSocket;
import java.net.Socket;
import java.net.URL;
import java.net.URLDecoder;
import java.util.LinkedList;

import javax.swing.JOptionPane;


public class Server {

    ServerSocket serverSocket = null;
    Socket clientSocket = null;
    static int defaultPort= 7341;
    String fromClientStr; //The string from the client
    ObjectOutputStream oos = null; //For SENDING data to client
    ObjectInputStream ois = null; //Getting info FROM client
    private static LinkedList<ServerMultiClient> allClients = new LinkedList<ServerMultiClient>();//Holds ALL client connections
    public static int serverID = 1; //Unique IDs for client from server. Starts are 1. Note: If you a user gets a Server ID LESS than one, something is wrong
    private static boolean graphsReady = false; //This boolean is checked by ServerMultiClient to see if the Graphs are ready, if they are, ServerMultiClient will send the graphs to their Clients


    public static void main(String[] args) {

        //Run server code in a new thread so the GUI will respond
        Runnable runServer = new Runnable(){
            public void run(){
                startServer();
            }
        };
        Thread startServer = new Thread(runServer);
        startServer.start();

    }

    private static void startServer(){

        ServerSocket serverSocket = null;
        boolean listening = true;

        //Set up the connection
        try {
            serverSocket = new ServerSocket(getPort());
        } catch (IOException e) {
            JOptionPane.showMessageDialog(null,
                    "Could not listen on port: " + getPort(),
                    "Error",
                    JOptionPane.ERROR_MESSAGE);
        }

        //Start listening for new Clients to connect
        while (listening){
            try {
                ServerMultiClient newClient = new ServerMultiClient(serverSocket.accept(), serverID++); //Accept a new client
                newClient.start(); //Start this new client
                allClients.add(newClient); //Add this new client to the list of all clients

            } catch (IOException e) {
                e.printStackTrace();
                Runnable runError = new Runnable(){
                    public void run(){
                        JOptionPane.showMessageDialog(null,
                            "Failed Accepting Client",
                            "Error",
                            JOptionPane.ERROR_MESSAGE);
                    }
                };
                Thread thrError = new Thread(runError);
                thrError.start();

            }
        }

        try {
            serverSocket.close();
        } catch (IOException e) {
            e.printStackTrace();
            JOptionPane.showMessageDialog(null,
                    "Could not close server socket",
                    "Error",
                    JOptionPane.ERROR_MESSAGE);
        }

    }

    //Returns the port from the box
    private static int getPort(){
        return defaultPort;
    }

    //This method finds and returns the main program path of the main jar file.
    public static String getProgramPath() throws IOException{
        URL url = Server.class.getProtectionDomain().getCodeSource().getLocation(); //Gets the path
        String jarPath = URLDecoder.decode(url.getFile(), "UTF-8"); //Should fix it to be read correctly by the system
        String parentPath = new File(jarPath).getParentFile().getPath(); //Path of the jar
        return parentPath + File.separator;
    }

}