ChatGUI problem

**candide56** · 06-11-2007, 09:02 AM

I am struggling with my ChatGUI please could you help me
I created two classes ChatServer and ChatClient
and in a package called Chatpack I created a ChatGUI class, a Send class, a Receive class
however when I type a message and click the send button nothing happens
indeed I do not know what to put inside the send.addActionListener in the ChatGUI
here it is

Java Code:

package Chatpack;

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class ChatGUI extends JFrame
{
	public static JTextField inputText;

	public static JTextArea message;

	public static JButton exit, send;

	String lastMessageSent;	
	private boolean available = false;
   
    	public ChatGUI()
	{
	String lastMessageSent = " ";
             send = new JButton("Send");
        	
	send.addActionListener(new ActionListener()
	{
	        public void actionPerformed(ActionEvent e)
	       {
				
	        }	// close the actionPerformed(ActionEvent e)
	});
            	exit = new JButton("Exit");
        	
	exit.addActionListener(new ActionListener()
	{
	        public void actionPerformed(ActionEvent e)
	       {
	           System.exit(0);
	       }	// close the actionPerformed(ActionEvent e)
	});
              
	inputText = new JTextField(40);
	inputText.setBackground(Color.WHITE);
		
	inputText.addActionListener(new ActionListener()
	{
	         public void actionPerformed(ActionEvent e)
	        {
	              String lastMessageSent = inputText.getText();
	              postMessage("Sent: " + lastMessageSent);	            	
                      }	// close the actionPerformed(ActionEvent e)
	});	// close the add.ActionListener
	
	message = new JTextArea();
        	message.setLineWrap(true);
	message.setWrapStyleWord(true);
	message.setEditable(false);
	message.setBackground(Color.WHITE);
	JScrollPane scroller = new JScrollPane(message);
	setPreferredSize( new Dimension(650,450)); 
	setBackground(Color.GRAY);                
	setLayout(new BorderLayout(5,5));           
	JPanel bottom = new JPanel();
	bottom.setBackground(Color.GRAY);
        	bottom.add(inputText);
        	bottom.add(send);
	JPanel top = new JPanel();
	top.setBackground(Color.GRAY);
        	top.add(exit);
	add(bottom, BorderLayout.SOUTH);
        	add(scroller, BorderLayout.CENTER);
	add(top, BorderLayout.NORTH);
	setTitle("MyChat Program");
	}	// close the ChatGUI constructor

	synchronized public String getInputText()
	{
	       while(available == false)
	      {
	           try
	          {
	                wait();
	          }
	          catch (InterruptedException e)
	          {
	          }
	      }	// close while block
	       available = false;
	       notifyAll();
	       return inputText.getText();
	}	// close getInputText method

	synchronized public void setInputText(String inputText)
	{
	        while (available == true)
	        {
	            try 
	           {
	                wait();
	           }
	           catch (InterruptedException e)
	          {
	           }
	          }	// close while block
	          available = true;
	          notifyAll();
		
		
	}	// close setInputText(String inputText) method
	
	synchronized private void sendMessage(String lastMessageSent) 
	{
	          message.append(lastMessageSent + "\n");
	}
             public void actionPerformed(ActionEvent e)
	{
	         String lastMessageSent = inputText.getText();
	         message.append(lastMessageSent + "\n");
	}	// close the actionPerformed(ActionEvent e)
}	// close ChatGUI class

here is the send class

Java Code:

package Chatpack;

import java.io.*;
import java.net.Socket;


public class Send extends Thread
{
	private Socket sock;
	private String lastMessageSent;
	
	private PrintWriter writer;
             public ChatGUI myGUI;

     	
    	public Send(ChatGUI gui, Socket socket)
	{
	         sock = socket;
	         String lastMessageSent = "";
	         myGUI = gui;
	         try
	        {
	              writer = new PrintWriter(socket.getOutputStream());
	         }	// close try block
    	         catch(IOException ioe)
    	         {
       	                System.out.println("Could not create output stream from socket");
       	                ioe.printStackTrace();
	         }	// close catch(Exception ioe)

         	
	}	// close Send(ChatGUI gui, Socket socket) constructor
        
	public void run()
	{
	         while(true)
	        {
	              if(!(lastMessageSent.equals(myGUI.lastMessageSent)))
	             {
	                   String lastMessageSent = myGUI.lastMessageSent;
	                   writer.println(lastMessageSent);	
                                writer.flush(); 
	             }	//close if block
                          try
	             {
	                      sleep(500);
	             }
	             catch(java.lang.InterruptedException ie) 
	            {
	                           ie.printStackTrace();
	            }

	        }	// close while loop
		 	
	}	// close run method
	
	public void finalize()
	{
    	            try
	            {
	                      writer.close();
	                      sock.close();
	            }	// close try block
	            catch (IOException e)
	           {
	           }	            // catch (IOException e)
	}	// close void finalize


}	// close Send class

here is my Receive class

Java Code:

package Chatpack;

import java.net.Socket;
import java.io.*;

public class Receive extends Thread
{
		
	private String lastMessageSent;

	private BufferedReader bReader;
	
	private Socket sock;
		
	public ChatGUI myGUI; 

	public Receive(ChatGUI gui, Socket socket)
	{
	           sock = socket; 
	           lastMessageSent = "";
                       myGUI = gui;
	          try
	         {
	                   bReader = new BufferedReader( new InputStreamReader socket.getInputStream()));
	         }	// close try block
    	         catch(IOException ioe)
    	        {
       	                 System.out.println("Could not create input stream from socket");
       	                 ioe.printStackTrace();
	         }	// close catch(Exception ioe)
	}	// close receive (ChatGUI gui, Socket socket)constructor
	public void run()
	{
	          try
	          {
	                 while(true)
	                {
	                           lastMessageSent = bReader.readLine() + "\n";
	                           try
	                          {
	                                   sleep(500);
	                          }
                             	 catch(java.lang.InterruptedException ie) 
                                       {
	                                   ie.printStackTrace();
	                           }
	                   }     // close while loop
         		 catch(IOException e)
	             {
	             }	// close catch (IOException e)				}	// close run method
	public void finalize()
	{
    	          try
	          {
	                    bReader.close();
	                   sock.close();
	           }	// close try block
	          catch(IOException e)
    	          {
       	          }	// close catch(Exception e)
	}	// close void finalize

}	// close Receive class

here is my ChatServer

Java Code:

import java.net.ServerSocket;
import java.net.Socket;
import java.io.*;

import Chatpack.*;


public class ChatServer
{
	
        private static final int intPortNumber = 4321;
 	
	
            ChatGUI myGUI;
	Send mySend;
	Receive myReceive;

	public ChatServer(ChatGUI gui, Send send, Receive receive)
	{	
	myGUI = gui;
	mySend = send;
	myReceive = receive;
	}	// close ChatServer(ChatGUI gui, Send send, Receive receive) constructor
		
	public static void main(String args[]) 
	{
        	Socket clientSocket = null;
  	ServerSocket serverSocket = null; 
	clientSocket = null;
	try
	{
	serverSocket = new ServerSocket(intPortNumber);
	clientSocket = serverSocket.accept();
	}	// close try block
	catch (IOException e)
	{
	System.err.println("Could not listen on port: 4321.");
	System.err.println(e.getMessage());
	System.exit(1);
	}	// close catch(IOException e)
   	ChatGUI gui = new ChatGUI();
	Send send = new Send(gui, clientSocket);
	Receive receive = new Receive(gui, clientSocket);
	send.start();
	receive.start();
	}	//close main method
        
}	//close ChatServer class

and finally the ChatClient

Java Code:

import java.net.Socket;
import java.io.*;

import Chatpack.*;

public class ChatClient
{
	
	private static final int intPortNumber = 4321;	 
	private static String address;
	
	ChatGUI myGUI;	
	Send mySend;
	Receive myReceive;

	public ChatClient(ChatGUI gui, Send send, Receive receive)
	{	
	myGUI = gui;
	mySend = send;
	myReceive = receive;
	}	// close ChatClient(ChatGUI gui, Send send, Receive receive) constructor
	
	public static void main(String args[])
            {
	Socket clientSocket = null;
	clientSocket = null;
	BufferedReader keyboardReader = null;
	try
	{
	clientSocket = new Socket(address,intPortNumber);
	keyboardReader = new BufferedReader(new InputStreamReader(System.in));
            System.out.print("Enter the IP address for the server: ");
            address = keyboardReader.readLine();
	}	// close try block
	catch (IOException ioe)
	{
	System.out.println("There was an Input/output problem");
	System.out.println(ioe.getMessage());
	System.exit(1);
	}	// close catch(IOException) block

	ChatGUI gui = new ChatGUI();
	Send send = new Send(gui, clientSocket);
	Receive receive = new Receive(gui, clientSocket);
	send.start();
	receive.start();
	
	}	//close main method

}	//close ChatClient class

here there are
please help me with this problem

levent · 06-12-2007, 01:19 PM

Hi

First of all you don't need these lines in your ChatClient. So i commented them. Those lines block the GUI without any reason since you already know ip address of the server:

Java Code:

keyboardReader = new BufferedReader(new InputStreamReader(System.in));
System.out.print("Enter the IP address for the server: ");
address = keyboardReader.readLine();

After commenting those lines, your code will work and both sides will send whatever you wrote in the textfield continuously. But i guess you dont want this, you want to send the data only when the user clicks send button. For that aim you need to modify run method of your Send class. You can define a boolean flag there. When user clicks to the "Send" button, you can set this flag on and thread only send content of the textfield when this flag is on.

Let us know if something is unclear or you have other problems.

**candide56** · 06-12-2007, 11:18 PM

Thank you very much for your help. I removed the lines you suggested but Cannot figure out how to do the boolean flag.
In the ChatGUI I left empty the
send.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{

because I do not know what to put in it.
in addition I cannot run the chat anymore as
I have this
Exception in thread "Thread-2" java.lang.NullPointerException
at Chatpack.Send.run(Send.java:63)
Could you help me with this
again thank you

**Jamie** · 06-13-2007, 11:43 PM

because I do not know what to put in it.
in addition I cannot run the chat anymore as
I have this
Exception in thread "Thread-2" java.lang.NullPointerException

Then do not remove those lines. I guess the problem was related to a netbeans bug. Same happened to me. It just did not ask me the ip address, then i removed those lines and it worked without those lines.

Cannot figure out how to do the boolean flag.

I noticed that you have a different logic there which should work too. You just seem to use "lastMessageSent" variable in Send class wrongly.

You already defined it as a class variable at the top of your class. When you use "String lastMessageSent = "";" and "String lastMessageSent = myGUI.lastMessageSent;" in your methods, you are defining a new variable called lastMessageSent. So do not use String keyword before your variable name while using it inside methods.

Good luck.