Chat server with multiple clients

Question

I am beginner in Java programming. I am trying to build a chat server in which there will be 1 server and multiple clients(at present there are only 2 clients).

Logic: Say there are 2 clients A and B

When A sends a message to B, the message must be first processed by the server and then passed to B and vice versa.

In the window the message from A should be displayed as (Example)
A: Hi
B: Hi
A: How are you ?
B: I am fine

Problem: When I run the server first it runs successfully.
But when I run the client the window is just stuck, i.e it does not respond.

What I want to know is that how can the above communication be done ? and what can be the effective code.

Please ignore the UI design. I would like the solution only to the above logic

Please note that you might find my code inefficient and there might also be some junk code.

Class Name: Server.java

package chatserver;

import java.io.DataInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.ServerSocket;
import java.net.Socket;

import javax.swing.JFrame;

public class Server {

    Socket soc;

    ServerSocket s = null;

    public Server() throws IOException
    {
        try
        {
            s = new ServerSocket(6633);
            while(true)
            {
                soc =s.accept();
                ServerHandle handle = new ServerHandle(soc);
                Thread t1 = new Thread(handle);
                t1.start();
            }
        }
        catch(Exception e)
        {
            System.out.println(e);
            //should be e.printStackTrace();
        }
        finally
        {
            if(s != null)
            {
                s.close();
            }   
        }
    }

    public static void main(String[] args) 
    {
        // TODO Auto-generated method stub

        try {
            new Server();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }   
    }
}

Server handler class
class Name: ServerHandle.java

package chatserver;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.net.Socket;

public class ServerHandle implements Runnable {

    Socket s1;
    BufferedReader reader;
    PrintWriter write;
    String msg;

    public ServerHandle(Socket s1)
    {
        this.s1 = s1;
    }

    public void run()
    {

        try {
            reader = new BufferedReader(new InputStreamReader(s1.getInputStream()));
            write = new PrintWriter(new OutputStreamWriter(s1.getOutputStream()));

            while((msg = reader.readLine()) != null)
            {
                write.write(msg);   
            }   
        }
        catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        finally
        {
            try {
                s1.close();
                reader.close();
                write.close();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
    }
}

Client Class
Class name: Client.java

package chatserver;

import java.awt.Container;
import java.awt.FlowLayout;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.net.Socket;
import java.net.UnknownHostException;

import javax.swing.*;

public class Client implements ActionListener
{
    JTextArea textArea;
    private JFrame frmChatWindow;
    private JTextArea textArea_1;
    JTextField username;

    JButton submit;
    JFrame j;
    JFrame jf;
    BufferedReader reader;
    PrintWriter write;
    String msg;
    Socket s;

    public Client() throws Exception, IOException
    {
        try
        {
            s = new Socket("localhost", 6633);
            reader = new BufferedReader(new InputStreamReader(s.getInputStream()));
            write = new PrintWriter(new OutputStreamWriter(s.getOutputStream()));

            j = new JFrame("PLAIN");
            j.setBounds(500, 150, 300, 400);

            JPanel panel = new JPanel();
            j.add(panel);
            GridBagLayout gb = new GridBagLayout();
            panel.setLayout(gb);

            GridBagConstraints c = new GridBagConstraints();

            JLabel label = new JLabel("User Name");
            c.gridx = 0;
            c.gridy = 0;
            c.fill = GridBagConstraints.HORIZONTAL;
            c.anchor = GridBagConstraints.NORTHWEST;
            c.ipadx = 5;
            c.ipady = 5;

            c.insets = new Insets(7, 7, 7, 7);

            panel.add(label, c);

            username = new JTextField(10);

            c.gridx = 1;
            c.gridy = 0;

            c.fill = GridBagConstraints.HORIZONTAL;
            c.anchor = GridBagConstraints.WEST;
            c.ipadx = 5;
            c.insets = new Insets(7, 7, 7, 7);

            panel.add(username, c);

            JLabel password = new JLabel("Password");
            c.gridx = 0;
            c.gridy = 1;
            c.fill = GridBagConstraints.HORIZONTAL;
            c.anchor = GridBagConstraints.WEST;
            c.ipadx = 5;
            c.insets = new Insets(7, 7, 7, 7);

            panel.add(password, c);

            JPasswordField pass = new JPasswordField(10);
            c.gridx = 1;
            c.gridy = 1;
            c.fill = GridBagConstraints.HORIZONTAL;
            c.anchor = GridBagConstraints.WEST;
            c.insets = new Insets(7, 7, 7, 7);

            panel.add(pass, c);

            submit = new JButton("Submit");
            c.gridx = 1;
            c.gridy = 6;
            c.fill = GridBagConstraints.HORIZONTAL;
            c.anchor = GridBagConstraints.WEST;
            c.insets = new Insets(7, 7, 7, 7);

            panel.add(submit, c);

            submit.addActionListener(this);
            j.setVisible(true);
            j.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);

            while ((msg = reader.readLine()) != null)
            {
                display(msg);
            }
        }

        catch (Exception e)
        {
            System.out.println(e);
        }
        finally
        {
            s.close();
            reader.close();
            write.close();
        }
    }

    private void display(String msg2)
    {
        textArea_1.append("Server" + ": " + msg2);
    }

    public void actionPerformed(ActionEvent e)
    {
        // TODO Auto-generated method stub
        j.dispose();
        frmChatWindow = new JFrame();
        frmChatWindow.setResizable(false);
        frmChatWindow.setTitle("Chat Window");
        frmChatWindow.setBounds(100, 100, 316, 300);
        frmChatWindow.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        SpringLayout springLayout = new SpringLayout();
        frmChatWindow.getContentPane().setLayout(springLayout);

        textArea = new JTextArea();
        springLayout.putConstraint(SpringLayout.WEST, textArea, 10, SpringLayout.WEST, frmChatWindow.getContentPane());
        springLayout.putConstraint(SpringLayout.SOUTH, textArea, 31, SpringLayout.SOUTH, frmChatWindow.getContentPane());
        springLayout.putConstraint(SpringLayout.EAST, textArea, 229, SpringLayout.WEST, frmChatWindow.getContentPane());
        textArea.setLineWrap(true);
        frmChatWindow.getContentPane().add(textArea);

        JButton btnNewButton = new JButton("Send");
        springLayout.putConstraint(SpringLayout.NORTH, textArea, 0, SpringLayout.NORTH, btnNewButton);
        springLayout.putConstraint(SpringLayout.SOUTH, btnNewButton, -58, SpringLayout.SOUTH, frmChatWindow.getContentPane());
        springLayout.putConstraint(SpringLayout.EAST, btnNewButton, -10, SpringLayout.EAST, frmChatWindow.getContentPane());
        frmChatWindow.getContentPane().add(btnNewButton);

        JButton btnLogout = new JButton("Logout");
        springLayout.putConstraint(SpringLayout.NORTH, btnLogout, 10, SpringLayout.NORTH, frmChatWindow.getContentPane());
        springLayout.putConstraint(SpringLayout.EAST, btnLogout, -10, SpringLayout.EAST, frmChatWindow.getContentPane());
        frmChatWindow.getContentPane().add(btnLogout);

        textArea_1 = new JTextArea();
        textArea_1.setEditable(false);
        textArea_1.append(null);
        springLayout.putConstraint(SpringLayout.NORTH, textArea_1, 24, SpringLayout.NORTH, frmChatWindow.getContentPane());
        springLayout.putConstraint(SpringLayout.WEST, textArea_1, 10, SpringLayout.WEST, frmChatWindow.getContentPane());
        springLayout.putConstraint(SpringLayout.SOUTH, textArea_1, -19, SpringLayout.NORTH, textArea);
        springLayout.putConstraint(SpringLayout.EAST, textArea_1, -6, SpringLayout.WEST, btnLogout);
        frmChatWindow.getContentPane().add(textArea_1);

        btnLogout.addActionListener(new Test2());
        btnNewButton.addActionListener(new ActionListener()
        {
            public void actionPerformed(ActionEvent arg0)
            {
                String s = new String();
                s = textArea.getText();
                sendmsg(s);
                getwrite();
            }
        });
        frmChatWindow.setVisible(true);
    }

    private void getwrite()
    {
        write.write(username.getText());
    }

    public void sendmsg(String g)
    {
        textArea_1.append(username.getText() + " " + ": " + g + "\n");
    }

    class Test2 implements ActionListener
    {
        public void actionPerformed(ActionEvent e)
        {
            frmChatWindow.dispose();
            j.setVisible(true);
        }
    }

    public static void main(String[] args)
    {
        // TODO Auto-generated method stub
        SwingUtilities.invokeLater(new Runnable()
        {
            public void run()
            {
                try
                {
                    new Client();
                }
                catch (IOException e)
                {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
                catch (Exception e)
                {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
            }
        });
    }
}

'Please ignore the UI design.' Please *remove* everything that is not related to your problem. See http://sscce.org/ — , Jul 09 '14 at 07:46
No, it is not. Socket programming has nothing to do with UI. — , Jul 09 '14 at 07:49
Please read my whole question it does not deal with the socket alone — Memory bot, Jul 09 '14 at 07:52
Is it necessary for you to use a `Socket` for the chat messages? or can you use external libraries? — EpicPandaForce, Jul 09 '14 at 08:00
The problem is obviously that you are not running the networking on a second thread and thus you are freezing the event handling of the window, although in Swing, the way to do that is to use a `SwingWorker` and *NOT* just a `Thread` or `Runnable`. — EpicPandaForce, Jul 09 '14 at 08:04
If you can use third party libraries, I'd recommend using KryoNET: http://stackoverflow.com/questions/24134655/kryonet-packet-not-sent/24452428#24452428 — EpicPandaForce, Jul 09 '14 at 08:05
In fact, look at http://stackoverflow.com/questions/14617331/java-socket-swingworker-running-but-no-message-received-or-transmitted if you still want to go for the socket+gui approach — EpicPandaForce, Jul 09 '14 at 08:09
To the person who was voted this post down. Do you think that the above question does not show research ? How come ? — Memory bot, Jul 09 '14 at 08:19

score 1 · Accepted Answer · answered Jul 09 '14 at 09:22

The issue is You are Reading from Clients Input and Writing to Clients Output. Basically you are sending whatever client sends back just a Ping Server.

ServerHandler.java

    while((msg = reader.readLine()) != null)
    {
        write.write(msg);
    }

This combined with you initializing the Socket at the Client constructor causes your UI to freeze.

Client.java

    s = new Socket("localhost", 6633);
    reader = new BufferedReader(new InputStreamReader(s.getInputStream()));
    write = new PrintWriter(new OutputStreamWriter(s.getOutputStream()));

And right below,

    while ((msg = reader.readLine()) != null)
    {
        display(msg);
    }

Your design is wrong for a Connection Oriented (TCP), Multi Client Chat Server. You need to sit down and draw a diagram on how to write from the beginning.

Could you please tell me as how can I accomplish this ? – Memory bot Jul 09 '14 at 09:33 — Memory bot, Jul 09 '14 at 09:33

Chat server with multiple clients

1 Answers1