GUI Freezes once socket server is started

Question

Here's my problem and I am stumped. I have an application which starts a
socket server and waits for clients to connect. Once connected, the
server queries XML to the client for display.
My problem is when I start the server my GUI freezes. I have a simple
GUI with a start and stop button made in JBuilder. Although the server is running fine and the application works (I can connect and query with my client) the GUI freezes and I have to CTRALTDEL to close the app.
The method below (see after message) is in the main Application.java class and my GUI is being created in the Frame1.java class. The Frame class has a listener for the button press which calls startServer in
Application. This was developed in JBuilder Personal edition.
I keep reading about InvokeLater but not sure if this is what I need. I feel like what is happening is the server starts and the app listens for clients and ignores the GUI.
Any suggestions would be helpful as madness is setting in.
Thnaks.
public static void startServer() {
try{
int intPort=9999;
ServerSocket server = new ServerSocket(intPort);
System.out.println("Server started...waiting for clients.");
while(true){
Socket objSocket = server.accept();
SocketClient client = new SocketClient(objSocket);
client.start();
catch(IOException ioe){
//dump error
Here is how the server is being started:
void button1_actionPerformed(ActionEvent e) {
try{
startserver.main(); //make call to start the server
label2.setText("Running");
catch (Exception ie) {
System.err.println("Could not listen on port: 9999.");
System.exit(-1);
}

Answer 1

Swing executes all GUI related code (event handling, painting, etc.) in the so-called event dispatching thread. If you call a blocking method like ServerSocket.accept in this thread, it is blocked and unable to perform further gui tasks.
public class MyServerThread extends Thread
    private ServerSocket serversocket;
    public void run()
        try
            this.sserversocket = new ServerSocket(9999);
            while(!Thread.interrupted())
                Socket socket = serversocket.accept();
                new SocketClient(socket).start();
        catch(IOException ex)
            ex.printStacktract();
    public void shutdown()
        if(this.serversocket != null)
            //closing the socket will cause accept() to throw an exception and therefor quit its loop
            try { this.serversocket.close(); } catch(IOException ignored) {}
            this.interrupt();
            this.serversocket = null;
//in your GUI class
private MyServerThread serverthread;
void startserver()
    serverthread = new MyServerThread();
    serverthread.start();
void stopserver()
    serverthread.shutdown();
    serverthread = null;
}