Question

I have an java application using Socket TCP/IP and GUI. Server always listens connection and receives message from client. When server received message, it will show a swing form.
My trouble is when I click on close button, the application will stop although I set server socket ALWAYS listens connection (by put method serverSocket.accept() in loop while(true)).
How can I solve that problem ?

Here is my code on Server:
public class TCPServer {

ServerSocket server = null;
BufferedReader in;
PrintWriter out;
Socket client = null;

//open serverSocket
public void openServer() {
    try {
        server = new ServerSocket(1234);
    } catch (Exception e) {
        e.printStackTrace();
    }
}

//accept connection and read data
public void listening() {
    try {

        while (true) {
            client = server.accept();
            in = new BufferedReader(new InputStreamReader(client.getInputStream()));
            out = new PrintWriter(client.getOutputStream(), true);
            //read data from stream
            String s = in.readLine();
            System.out.println("String receive:  " + s);

            new NewJFrame().setVisible(true);
        }
    } catch (Exception e) {
        e.printStackTrace();
    }
}

public void closeServer() {
    try {
        if (out != null) {
            out.close();
        }

        if (in != null) {
            in.close();
        }
        if (client != null) {
            client.close();
        }
        if (server != null) {
            server.close();
        }
    } catch (Exception e) {
    }
}

public static void main(String arg[]) {
    TCPServer server = new TCPServer();
    server.openServer();
    server.listening();
    server.closeServer();
}

}

Answer 1

From Javadoc:

      EXIT_ON_CLOSE 
      The exit application default window close operation.

In the NewJFrame class, remove this: setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

This is making the whole application shutdown when the close button is hit!

Replace it by:
setDefaultCloseOperation(javax.swing.WindowConstants.DISPOSE_ON_CLOSE);

This way you are sure only the window is disposed, not the whole application