Java client server connection problem

[Elaine121]

Hi i've been batteling for hours and can't seem to find the problem. When my server runs and I press the connect button the gui freezes until the client gui is terminated.. only then the gui becomes active again and displays the messages.

Here is my server code:

import java.io.*;
import java.net.*;
 
 
public class serverForm extends javax.swing.JFrame {
 
   private PrintWriter output = null; 
   private BufferedReader input = null; 
   private ServerSocket server = null; 
   private Socket connection = null; 
 
    public serverForm() {
        initComponents();
    }
 
 
    public void runServer()
   {
            try 
      {
         server = new ServerSocket( Integer.parseInt(jTextField1.getText()), 2 ); 
 
 
} catch (IOException e) {
            System.err.println("Could not listen on port: 4444.");
            System.exit(1);
        }
 
            try 
            {
              waitForConnection();      
 
            } 
 
            catch ( IOException ioException ) 
     {
        ioException.printStackTrace();
     }
 
            try 
            {
              output = new PrintWriter(connection.getOutputStream(), true);
              input = new BufferedReader(new InputStreamReader(connection.getInputStream()));  
              processConnection();
            } 
 
            catch ( IOException ioException ) 
     {
        ioException.printStackTrace();
     }
            finally 
            {
               closeConnection(); 
 
            }
 
}
 
   private void waitForConnection() throws IOException
   {
     statuslbl.setText( "Waiting for connection\n" );
      connection = server.accept();          
      statuslbl.setText( "Connection received from: " + connection.getInetAddress().getHostName() );
   } 
 
 
 
      private void processConnection() throws IOException
   {
     String inputLine, outputLine;
       protocol kkp = new protocol();
 
        outputLine = kkp.processInput(null);
        output.println(outputLine);
 
        jTextArea1.setText(jTextArea1.getText() + outputLine + "\n");
        while ((inputLine = input.readLine()) != null)
        {
             outputLine = kkp.processInput(inputLine);
 
             jTextArea1.setText(jTextArea1.getText() + inputLine + "\n");
                jTextArea1.setText(jTextArea1.getText() + outputLine + "\n");
      try 
      {
         output.println(outputLine);
      } 
      catch ( Exception e) 
      {
     statuslbl.setText( "Error writing object" );
      } 
 
 
             if (outputLine.equals("Bye."))
                break;
        }
 
 
 
 
      }
 
      private void closeConnection() 
   {
      statuslbl.setText( "Terminating connection" );
 
      try 
      {
 
         output.close();
         input.close();
         connection.close();
      } 
      catch ( IOException ioException ) 
      {
         ioException.printStackTrace();
      } 
   } 
 
 
 
       private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         
       runServer();
    }                                        
 
    /**
     * @param args the command line arguments
     */
    public static void main(String args[]) {
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new serverForm().setVisible(true);
            }
        });
 
    }

Here is protocol class which the server works from:

import java.net.*;
import java.io.*;
 
public class protocol {
    private static final int WAITING = 0;
    private static final int SENTKNOCKKNOCK = 1;
    private static final int SENTCLUE = 2;
    private static final int ANOTHER = 3;
 
    private static final int NUMJOKES = 5;
 
    private int state = WAITING;
    private int currentJoke = 0;
 
    private String[] clues = { "Turnip", "Little Old Lady", "Atch", "Who", "Who" };
    private String[] answers = { "Turnip the heat, it's cold in here!",
                                 "I didn't know you could yodel!",
                                 "Bless you!",
                                 "Is there an owl in here?",
                                 "Is there an echo in here?" };
 
    public String processInput(String theInput) {
        String theOutput = null;
 
        if (state == WAITING) {
            theOutput = "Knock! Knock!";
            state = SENTKNOCKKNOCK;
        } else if (state == SENTKNOCKKNOCK) {
            if (theInput.equalsIgnoreCase("Who's there?")) {
                theOutput = clues[currentJoke];
                state = SENTCLUE;
            } else {
                theOutput = "You're supposed to say \"Who's there?\"! " +
                "Try again. Knock! Knock!";
            }
        } else if (state == SENTCLUE) {
            if (theInput.equalsIgnoreCase(clues[currentJoke] + " who?")) {
                theOutput = answers[currentJoke] + " Want another? (y/n)";
                state = ANOTHER;
            } else {
                theOutput = "You're supposed to say \"" + 
                clues[currentJoke] + 
                " who?\"" + 
                "! Try again. Knock! Knock!";
                state = SENTKNOCKKNOCK;
            }
        } else if (state == ANOTHER) {
            if (theInput.equalsIgnoreCase("y")) {
                theOutput = "Knock! Knock!";
                if (currentJoke == (NUMJOKES - 1))
                    currentJoke = 0;
                else
                    currentJoke++;
                state = SENTKNOCKKNOCK;
            } else {
                theOutput = "Bye.";
                state = WAITING;
            }
        }
        return theOutput;
    }
}

And here is the client code:

import java.io.*;
import java.net.*;
 
public class ClientForm extends javax.swing.JFrame {
   private Socket kkSocket = new Socket();
   private PrintWriter out = null;
   private BufferedReader in = null;
    /** Creates new form NewJFrame */
    public ClientForm() {
        initComponents();
       }
 
    public void send()
    {
     if (kkSocket.isConnected() != true)
            statuslbl.setText("Please Connect First");
   else
       try
       {
           String client,server;
 
            client = clientInput.getText();               
            out.println(client);
            server = (String)in.readLine();
 
 
                if (server.equals("Bye."))
                {
                    in.close();
                    out.close();
                    kkSocket.close();
                }
 
            jTextArea1.setText(jTextArea1.getText() + "User : " + client + "\n");
            jTextArea1.setText(jTextArea1.getText() + "Server : " + server + "\n");   
            }
            catch (IOException e)
            {
            }
 
 
            clientInput.setText("");
 
 
 
    }
  private void connectbtnActionPerformed(java.awt.event.ActionEvent evt) {                                           
 
         try 
        {
         if (kkSocket.isConnected() == true)  
             kkSocket.close();
 
       kkSocket = new Socket(ipText.getText(),Integer.parseInt(portText.getText()));
 
 
 
        out = new PrintWriter(kkSocket.getOutputStream(), true);
        in = new BufferedReader(new InputStreamReader( kkSocket.getInputStream()));
 
        jTextArea1.setText(jTextArea1.getText() + "Server : " + (String)in.readLine() + "\n");
        } 
          catch (Exception e) 
          {
            statuslbl.setText("Can't Connect To Host");
          } 
 
        if (kkSocket.isConnected() == true)
             statuslbl.setText("Connected");
}                                          
 
    private void clientInputActionPerformed(java.awt.event.ActionEvent evt) {                                            
      send();
    }                                           
 
    private void sendbtnActionPerformed(java.awt.event.ActionEvent evt) {                                        
 send();
 
 
}                                       
 
 
 
    /**
     * @param args the command line arguments
     */
    public static void main(String args[]) {
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new ClientForm().setVisible(true);
            }
        });
 
    }

[JosAH]

@Elaine121
I didn't read all your code but given your description I conclude that you do all your processing in the EDT thread (Event Dispatch Thread). You are keeping that thread busy with your accept() and read() calls; they are blocking methods, i.e. they don't return until they have done their job. The EDT doesn't have any time anymore to do its job: painting components and listening for events.

Do all of your processing in another thread so the EDT can do its job while you do your job.

kind regards,

Jos

[Elaine121]

i'm not that familiar with threads. What's the best way to do that?

[JosAH]

@Elaine121
Create an implementation of the Runnable interface that handles all the socket communication; feed it to a new Thread and start the thread. That''s basically it.

kind regards,

Jos

[Elaine121]

That sounds easy to do and I tried looking it up and I'm sorry but I have no idea what to do. Im new at this so everything is a bit complicated for me

[Elaine121]

ok I don't know if I'm on the right track with this.. in my server class I created a new thread. But now when i run the server class and press the connect button it just gives me an IOexception.

public static void main(String args[]) {
        //java.awt.EventQueue.invokeLater(new Runnable() {
 
                 SwingUtilities.invokeLater(new Runnable() {
                 public void run() {
                new serverForm().setVisible(true);
                Thread newThread = new Thread(new serverForm());
                newThread.start();
            }
        });

}

[JosAH]

@Elaine121
Of course the Exception stack trace told you exactly where the exception happened; reading such stack traces actually helps you finding the bug ...

kind regards,

Jos

[Elaine121]

when the port number is already in the textbox then the server runs fine.. but when i enter a number myself thats when the exception occurs.

server = new ServerSocket( Integer.parseInt(jTextField1.getText())); // this gives exception
server = new ServerSocket( 63100); // this runs fine

Am i reading the number wrong?

[JosAH]

@Elaine121
If that code runs before you could enter a number in the text field there won't be a number yet and the parseInt() method will throw another Exception. Otherwise (if the field contains a valid number) all will be fine.

kind regards,

Jos

[Elaine121]

So then where must i put that code? i tried a couple of places but its still the same

[JosAH]

@Elaine121
You should only run that piece of code when the user has completed typing a number in that field. An event handler would do fine. It should start a thread that opens up a server and starts communicating with clients while the EDT goes on painting and listening for other events.

kind regards,

Jos