A beginner in socket programming

Question

Ok I am been stuck on this program for the whole day trying to figure out why I cannot connect to my server computer using sockets and threads.
I am trying to implement a instant messenger program where each user acts has both client/server. Each client creates a listening socket and all use a common port number, (in this case port 4444).
If client 1 wants to interact with client 2, client 1 query�s my MySQL database for their status. Now if their status is online, retrieve their current ip address. So far so good. My program does not with no problem.
Now comes the painful part. Now that client 1 knows client 2 is online and has his/hers ip, the next step is to connect to client 2�s listening socket using their ip and the port number 4444. Now after connecting to that socket, a new chat dialog gui is suppose to open from the client 2�s side. This new chat dialog gui (jframe) is a thread so that if other users wishes to interact with client 2, another new chat dialog thread will appear!
But in my case nope! Has soon as client 1 tries to establish a connection with client 2, boom. Error, connection refused: connect!!
Now I been searching through Google trying to understand what this means and so far I found null� now I posted before asking what that means and someone told me it means that I forgot to close the sockets and input, output streams. But how can I close it when I cannot even establish a connection with client 2??
Things I have tried:
I tried inputting myself, the actual ip of client 2 and guess what� no luck
I tried the client 2�s computer name, and same thing!
I tried to create a whole new main class just so that I can open and close the sockets and input/output stream and nope, no luck at all..
Now that you have a good understanding of my program. Here comes the code:
I�l start with the user_window, which is the main menu as you call it: this jframe once opened, is suppose to create a server socket to listen for connections. If a connection is made, load the chatdialog gui thread�
* user_window.java
* Created on 10 February 2006, 11:50
package icomm;
import java.sql.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.net.*;
import java.io.*;
* @author jonathan
public class user_window extends javax.swing.JFrame implements WindowListener {
protected String crnt_user;
protected String crnt_ip;
protected String dummy = "";
/** Creates new form user_window */
public user_window() {
initComponents();
listeningSocket();
addWindowListener( this );
public user_window(String users_name)
initComponents();
addWindowListener( this );
this.crnt_user = users_name;
private void exit()
MySQL_queries offline = new MySQL_queries();
offline.off_status(crnt_user);
JOptionPane.showMessageDialog(null, "you are about to close the program " + crnt_user, null, JOptionPane.ERROR_MESSAGE);
MySQL_queries query = new MySQL_queries();
query.off_status(crnt_user);
query.reset_ip(crnt_user);
System.exit(0);
public void windowClosing(WindowEvent e)
     exit();
/** This method is called from within the constructor to
* initialize the form.
* WARNING: Do NOT modify this code. The content of this method is
* always regenerated by the Form Editor.
// <editor-fold defaultstate="collapsed" desc=" Generated Code ">
private void initComponents() {
try {
Buddie_list =(javax.swing.JTree)java.beans.Beans.instantiate(getClass().getClassLoader(), "icomm.user_window_Buddie_list");
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (java.io.IOException e) {
e.printStackTrace();
label = new javax.swing.JLabel();
demo = new javax.swing.JButton();
jMenuBar1 = new javax.swing.JMenuBar();
jMenu1 = new javax.swing.JMenu();
Close = new javax.swing.JMenuItem();
jMenu2 = new javax.swing.JMenu();
profile = new javax.swing.JMenuItem();
jMenu3 = new javax.swing.JMenu();
getContentPane().setLayout(new org.netbeans.lib.awtextra.AbsoluteLayout());
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
getContentPane().add(Buddie_list, new org.netbeans.lib.awtextra.AbsoluteConstraints(10, 30, 230, 310));
getContentPane().add(label, new org.netbeans.lib.awtextra.AbsoluteConstraints(90, 390, -1, -1));
demo.setText("talk to shienna");
demo.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
demoActionPerformed(evt);
getContentPane().add(demo, new org.netbeans.lib.awtextra.AbsoluteConstraints(10, 360, -1, -1));
jMenu1.setText("File");
jMenu1.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jMenu1ActionPerformed(evt);
Close.setLabel("Close");
Close.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
CloseActionPerformed(evt);
jMenu1.add(Close);
jMenuBar1.add(jMenu1);
jMenu2.setText("Option");
profile.setText("Edit Profile");
profile.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
profileActionPerformed(evt);
jMenu2.add(profile);
jMenuBar1.add(jMenu2);
jMenu3.setText("Help");
jMenuBar1.add(jMenu3);
setJMenuBar(jMenuBar1);
pack();
// </editor-fold>
private void demoActionPerformed(java.awt.event.ActionEvent evt) {                                    
// TODO add your handling code here:
ChatDialog_c chatting = new ChatDialog_c(crnt_user, dummy);
chatting.setTitle("I-comm");
chatting.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
chatting.setSize(360, 500);
chatting.getSize();
chatting.setLocation(420,200);
chatting.setVisible(true);
private void CloseActionPerformed(java.awt.event.ActionEvent evt) {                                     
// TODO add your handling code here:
private void demo1ActionPerformed(java.awt.event.ActionEvent evt) {                                     
// TODO add your handling code here:
private void show_chat_window()
ChatDialog chat_gui = new ChatDialog();
chat_gui.setTitle("chat");
chat_gui.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
chat_gui.setSize(366, 480);
chat_gui.getSize();
chat_gui.setLocation(420,200);
chat_gui.setVisible(true);// TODO add your handling code here:
private void log_offActionPerformed(java.awt.event.ActionEvent evt) {                                       
private void locate_ip()
try
InetAddress a;
a = InetAddress.getLocalHost(); //get ip addrees
this.crnt_ip = a.getHostAddress(); //then store it in this variable
catch(UnknownHostException e)
JOptionPane.showMessageDialog(null, "Error, cant detect localhost", null, JOptionPane.ERROR_MESSAGE);
public void windowActivated(WindowEvent e) {}
     public void windowClosed(WindowEvent e) {}
     public void windowDeactivated(WindowEvent e) {}
     public void windowDeiconified(WindowEvent e) {}
     public void windowIconified(WindowEvent e) {}
     public void windowOpened(WindowEvent e)
locate_ip();
MySQL_queries new_ip = new MySQL_queries();
new_ip.update_ip(crnt_user, crnt_ip);
JOptionPane.showMessageDialog(null,"hello " + crnt_user + " your ip is" + crnt_ip, null, JOptionPane.ERROR_MESSAGE);
private void listeningSocket()
ServerSocket serverSocket = null;
boolean listening = true;
try
//listen in port 4444;
serverSocket = new ServerSocket(4444);
catch(IOException x)
JOptionPane.showMessageDialog(null, "cannot listen to port 4444", null, JOptionPane.ERROR_MESSAGE);
while(listening)
try
ChatDialog chat = new ChatDialog(serverSocket.accept());
catch(IOException x)
JOptionPane.showMessageDialog(null, "could not open chat window", null, JOptionPane.ERROR_MESSAGE);
private void jMenu1ActionPerformed(java.awt.event.ActionEvent evt) {                                      
// TODO add your handling code here:
private void profileActionPerformed(java.awt.event.ActionEvent evt) {                                       
// TODO add your handling code here:
* @param args the command line arguments
public static void main(String args[]) {
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
new user_window().setVisible(true);
Now for the chatdialog class: I forgot to mention that I have two versions of this class. One that is a thread and the other makes a connection to a thread, hope that makes sence�
package icomm;
import java.net.*;
import java.io.*;
import javax.swing.*;
import java.awt.event.*;
import java.awt.*;
public class ChatDialog_c extends javax.swing.JFrame implements WindowListener {
    protected String messege;
    private Socket socket = null;
    protected String ip2;
    private PrintWriter out = null;
    private BufferedReader in = null;
    private String user_name;
    private String status;
    /** Creates new form ChatDialog_c */
    public ChatDialog_c()
        initComponents();
        addWindowListener( this );
     public ChatDialog_c(String ip1)
        initComponents();
        addWindowListener( this );
        this.ip2 = ip1;
        //OptionPane.showMessageDialog(null, "error in closing sockdswdset " + ip2, null, JOptionPane.ERROR_MESSAGE);
     public ChatDialog_c(String user, String status)
        initComponents();
        addWindowListener( this );
        this.user_name = user;
    public void windowClosing(WindowEvent e)
        public void windowActivated(WindowEvent e) {}
     public void windowClosed(WindowEvent e) {
            try
                in.close();
                out.close();
                socket.close();
            catch(IOException x)
                x.printStackTrace();
                JOptionPane.showMessageDialog(null, "error in closing socket " + x.getMessage() + ip2, null, JOptionPane.ERROR_MESSAGE);
     public void windowDeactivated(WindowEvent e) {}
     public void windowDeiconified(WindowEvent e) {}
     public void windowIconified(WindowEvent e) {}
      public void windowOpened(WindowEvent e)
          MySQL_queries get_ip = new MySQL_queries();
          this.ip2 = get_ip.find_client(user_name);
           JOptionPane.showMessageDialog(null, user_name + ip2, null, JOptionPane.ERROR_MESSAGE);
            //create socket connection
            try
                socket = new Socket ("Shienna", 4444);
                out = new PrintWriter(socket.getOutputStream(), true);
                in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            catch(UnknownHostException x)
                x.printStackTrace();
                JOptionPane.showMessageDialog(null, "unknown  " + x.getMessage() + ip2, null, JOptionPane.ERROR_MESSAGE);
            catch(IOException x)
                x.printStackTrace();
                JOptionPane.showMessageDialog(null, "2 " + x.getMessage(), null, JOptionPane.ERROR_MESSAGE);
             try
                in.close();
                out.close();
                socket.close();
            catch(IOException x)
                x.printStackTrace();
                JOptionPane.showMessageDialog(null, "error in closing socket " + x.getMessage() + ip2, null, JOptionPane.ERROR_MESSAGE);
            while(true)
                try
                    String line = in.readLine();
                    convo_txt.append(line);
                catch(IOException x)
                    x.printStackTrace();
                    JOptionPane.showMessageDialog(null, "3 " + x.getMessage(), null, JOptionPane.ERROR_MESSAGE);
    /** This method is called from within the constructor to
     * initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is
     * always regenerated by the Form Editor.
    // <editor-fold defaultstate="collapsed" desc=" Generated Code ">                         
    private void initComponents() {
        jScrollPane1 = new javax.swing.JScrollPane();
        convo_txt = new javax.swing.JTextArea();
        jScrollPane2 = new javax.swing.JScrollPane();
        txt_messege = new javax.swing.JTextArea();
        send = new javax.swing.JButton();
        jMenuBar1 = new javax.swing.JMenuBar();
        jMenu1 = new javax.swing.JMenu();
        jMenu2 = new javax.swing.JMenu();
        getContentPane().setLayout(new org.netbeans.lib.awtextra.AbsoluteLayout());
        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
        jScrollPane1.setViewportView(convo_txt);
        getContentPane().add(jScrollPane1, new org.netbeans.lib.awtextra.AbsoluteConstraints(10, 20, 220, 280));
        txt_messege.setLineWrap(true);
        jScrollPane2.setViewportView(txt_messege);
        getContentPane().add(jScrollPane2, new org.netbeans.lib.awtextra.AbsoluteConstraints(10, 330, 220, 70));
        send.setText("Send");
        send.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                sendActionPerformed(evt);
        getContentPane().add(send, new org.netbeans.lib.awtextra.AbsoluteConstraints(10, 420, -1, -1));
        jMenu1.setText("File");
        jMenu1.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jMenu1ActionPerformed(evt);
        jMenuBar1.add(jMenu1);
        jMenu2.setText("Option");
        jMenuBar1.add(jMenu2);
        setJMenuBar(jMenuBar1);
        pack();
    // </editor-fold>                       
    private void sendActionPerformed(java.awt.event.ActionEvent evt) {                                    
        String text = txt_messege.getText();
        out.println();
        txt_messege.setText(new String(""));
        convo_txt.append(text);
    private void jMenu1ActionPerformed(java.awt.event.ActionEvent evt) {                                      
// TODO add your handling code here:
     * @param args the command line arguments
    public static void main(String args[]) {
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new ChatDialog_c().setVisible(true);
    }///////////////////////chat dialog thread/////////////////////
package icomm;
import java.net.*;
import java.io.*;
import javax.swing.*;
import java.awt.event.*;
import java.awt.*;
public class ChatDialog extends javax.swing.JFrame implements WindowListener, Runnable {
    protected String messege;
    private Socket client_user = null;
    /** Creates new form ChatDialog */
    public ChatDialog()
        initComponents();
        addWindowListener( this );
    public ChatDialog(String txt_messege)
        initComponents();
        addWindowListener( this );
        this.messege = txt_messege;
     public ChatDialog(Socket user)
         initComponents();
         addWindowListener( this );
         this.client_user = user;
    public void run()
        BufferedReader in = null;
        PrintWriter out = null;
        String error = "error has occured ";
        String messege = null;
         try
            //create input and output streams
            in = new BufferedReader(new InputStreamReader (client_user.getInputStream()));
            out = new PrintWriter(client_user.getOutputStream(), true);
            while(true)
               //read messege sent by user
               messege = in.readLine();
               //send data back to user
               out.println(messege);
               //append data on the text field
               convo_txt.append(messege + "\n");
               //chat_gui.setVisible(true);
               //-=inputs = new ChatDialog(messege);
           //out.close();
            //in.close();
            //client_user.close();
        catch (IOException e)
            //error messege
            e.printStackTrace();
            JOptionPane.showMessageDialog(null, error + e.getMessage(), null, JOptionPane.ERROR_MESSAGE);
    }If I can sort this problem out I would of completed the main part of my program. I have spent days on this and hope that anyone of you guys can take the time out and help me with my current situation. Thanks

Answer 1

update:
i have managed to sort out the connection refused
i know have anotehr problem: both client2 program freezes as soon as client 1 tries to initiate a connection to client 2!!!!!!!!
when client 2 logs into teh system. it freezes as soon as i press the button! but when client 1 attempts to conenct to client 2, client 2's program stops freezing and the chatdialog comes up showing nothing and freezes! my chadialog is suppose to show a file menu i made but it doesnt,. both clients freezes at this point. no error messeges occur...