Execute JFrame from Another JFrame

Question

I am making a client server application in which the server code is executed by a JFrame This is my server code when I call Show method from main method of MyServer class then it is working but when I call it from Key Event of Jframe then it is not showing the another Jframe. Please help.

public class MyServer 
    public void Show() throws IOException {
        ServerSocket ss = new ServerSocket(6666);
        new IPScanning().dispose();
        int count = 0;
        while (true) {
            Socket s = null;
            try {
                s = ss.accept();  
                SocketThread socketThread = new SocketThread(s, count);
                socketThread.start();
            } catch (Exception e) {
                ss.close();
                s.close();
                System.out.println(e);
            } finally {
                count++;
            }
        }
    }

    class SocketThread extends Thread {
        public void run() {
            try {
                EventQueue.invokeLater(new Runnable() {
                    @Override
                    public void run() {
                        ShowTable.INSTANCE.showdata(count, host, ip, username, os_name, os_arch, pro_detail, Mac_add, disk_size, max_memory);
                    }
                });
            } catch (Exception e) {
                System.out.println("Server Problem");
                System.out.println(e);
            }
        }
    }
}`

This is my Key Event

  private void jStartActionPerformed(java.awt.event.ActionEvent evt) {                                       
        MyServer ms=new MyServer();
        try {
            ms.Show();
        } catch (IOException ex) {
            System.out.println(ex);
        }
    }    

Code of another JFrame calling through SocketThread class.

 public enum ShowTable{
        INSTANCE;
        private JFrame f = new JFrame();
        private JTable jt = new JTable(new DefaultTableModel());
        private DefaultTableModel model = (DefaultTableModel) jt.getModel();
        private ShowTable() {
            jt.setBounds(30, 40, 200, 300);
            jt.setFocusable(false);
            jt.setRowSelectionAllowed(false);
            JScrollPane sp = new JScrollPane(jt);
            f.add(sp);
            f.setSize(1300, 600);
        }
        public void showdata(int count,String host,String ip,String username,String os_name,String os_arch,String pro_detail,String Mac_add,float disk_size,float max_memory){        
           f.setVisible(true);
        }
    }

Answer 1

private void jStartActionPerformed(java.awt.event.ActionEvent evt) {                                       
    MyServer ms=new MyServer();
    try {
        ms.Show();
    } catch (IOException ex) {
        System.out.println(ex);
    }
}       

Suggests that this method is been called in response to some action from the UI (like a button press), which would mean that the event is been dispatched from within the context of the Event Dispatching Thread.

This means that MyServer#show is been called within the context of the Event Dispatching Thread.

So if we have a look...

public void Show() throws IOException {
    ServerSocket ss = new ServerSocket(6666);
    new IPScanning().dispose();
    int count = 0;
    while (true) {
        Socket s = null;
        try {
            s = ss.accept();  
            SocketThread socketThread = new SocketThread(s, count);
            socketThread.start();
        } catch (Exception e) {
            ss.close();
            s.close();
            System.out.println(e);
        } finally {
            count++;
        }
    }
}

We can see that Show is creating an infinite loop AND calling a blocking method all within the context of the Event Dispatching Thread - blocking it and prevent the UI from ever been updated again.

Swing is both single threaded and not thread safe. This means:

• You should never perform any long running or blocking operations within the context of the event dispatching thread
• You should never update the state of the UI (or anything the UI relies on) from outside of the context of the Event Dispatching Thread

You need to go and have a read through Concurrency in Swing to gain a better understanding into the issue.

You should also pay close attention to Worker Threads and SwingWorker as they will help provide the answer to solving your question.

However, a overly simplest solution might be to simply use a another Thread to run the MyServer#Show method in...

private void jStartActionPerformed(java.awt.event.ActionEvent evt) {                                       
    new Thread(new Runnable() {
        @Override
        public void run() {
            try {
                MyServer ms=new MyServer();
                ms.Show();
            } catch (IOException ex) {
                System.out.println(ex);
            }
        }
}