Problem of a Jbutton actionlistener

[shashmita]

Please help me

i have a problem that whenever i run this program and during execution if i click the button then the remainig menubar and menuitems will not respond all the actions are blocked


package desktop;

import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;


public class SamplDesktop {

JFrame frame = new JFrame();
JMenuBar mb = new JMenuBar();
JMenu file = new JMenu("File");
JMenu edit = new JMenu("Edit");
JMenu view = new JMenu("View");
JMenu tools = new JMenu("Tools");
JMenu help = new JMenu("Help");

JMenuItem newconnection = new JMenuItem("NewConnection");
JMenuItem recentconnection=new JMenuItem("RecentConnection");
JMenuItem closeconnection=new JMenuItem("CloseConnections");
JMenuItem exit=new JMenuItem("Exit");


JFrame frame1 = new JFrame();
JDesktopPane desktop = new JDesktopPane();

JButton btn1=new JButton("Port1");

void run(){
frame.setJMenuBar(mb);
mb.add(file);
mb.add(edit);
mb.add(view);
mb.add(tools);
mb.add(help);
file.add(newconnection);
file.add(recentconnection);
file.add(closeconnection);
file.add(exit);
frame.add(btn1);

btn1.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e) {
ServerInitiator ser=new ServerInitiator();
ser.initialize(6666);
}
});

frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOS E);
frame.setExtendedState(frame.getExtendedState()|JF rame.MAXIMIZED_BOTH);
frame.setLayout(new FlowLayout());
frame.setSize(400, 125);
frame.setVisible(true);
}

public static void main(String[] args) {
SamplDesktop sd=new SamplDesktop();
sd.run();
}


}

i must access the object and the methods of the other class please help for me from this problem also

Thanks in Advance

[chaarmann]

It's because when you click the button, the commands

ServerInitiator ser=new ServerInitiator();
ser.initialize(6666);

inside your ActionListener method are called.
So if these commands take a long time or are crashing, the program can't go on and draw the menu or respond to more mouseclicks from you.
You can avoid that by putting these commands inside a thread and then run the thread when the button is clicked.

666, the number of the beast! And 6666, an even bigger one.
No wonder the devil doesn't let it work.

[chaarmann]

Shashmita send me a private email instead of replying here.
This is not a good idea, see forum guidelines. There is no benefit for others that have the same problem if I reply her privately back and I can't see anything private in her email, so I am posting it here:

@shashmita
She has sent me a huge, unindented program that took me a long time to scan, but only a small part is important, which I will quote here:

...
frame.add(btn1);
btn1.addActionListener(new ActionListener(){
  JFrame frm=new JFrame("Server");
  JDesktopPane desktop = new JDesktopPane();
  int port=666;
  ServerSocket sc;
  Socket client;
  public void actionPerformed(ActionEvent e) {
  try {
    sc = new ServerSocket(port);
    drawGUI();
    while(true){
      client = sc.accept();
      JOptionPane.showMessageDialog(frm,"New client Connected to the server");
       new ClientHandler(client,desktop);
       client = sc.accept();.
    }
...
 

First, Shashmita, your main program is running as a thread or process, that's right. But that's not what I ment. When you click on the button the method actionPerformed is called, but instead of executing your code there, you should open a new thread there and start it (see java.lang.Thread how to create a thread). This thread then will run your code. That means your program (main thread) and your child thread (the code inside actionPerformed ) will run in parallel. In this way, it doesn't matter if the code in your child thread will run only seconds, hours or forever. Because the main thread doesn't need to wait until your child thread finishes and can draw the GUI-elements right away. No blocking anymore.

In the code above you sent me, when you click a button you are entering a while-loop that runs forever: "while (true)". It is only stopped if an error happens. So you can't see your GUI drawn until an error happens. Worse, if it runs without errors, you will wait forever, all "remaining componentes" are blocked.
I/O-operations, like network connections, can take a long time. There is hardware involved, firewalls, routers, shared throughput etc., so that you can never be sure that your request will only take milliseconds. I mean, it can usually take milliseconds to run, but you can not rely on it. But under some circumstances it will run for hours! That's why it is better to open a new thread and perform the I/O-operation there. So that your main program will not be blocked under any circumstances.