Thread problem

Junior Poster

124 posts since Mar 2009

Reputation Points: 6

Solved Threads: 0

Not certain that I understand the Q, but you can only have 1 run() in a class, so if there are other things you want to start new threads for you need an additional small Runnable class to do it. You can use an anonymous inner class (Google it if unfamiliar) for this, like this:

new Thread(new Runnable() {
  public void run() {
      // call a method in your main class to do the work 
  }
}).start();

Posting Genius

Moderator

6,371 posts since Apr 2008

Reputation Points: 2,130

Solved Threads: 1,073

Hello,
Thanks for the answer. I am having another problem. My application freeze. I have done a similar application, chat and it was working, now i applied the same logic for the ftp and its freezing. Can someone help me please.

Junior Poster

124 posts since Mar 2009

Reputation Points: 6

Solved Threads: 0

This is the server class:

package ignisftpv20;

import java.net.*;
import java.io.*;
import javax.swing.JOptionPane;


public class FTPServer extends javax.swing.JFrame implements Runnable {





    public FTPServer() {
        initComponents();
    }



    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">
    private void initComponents() {

        btnServer = new javax.swing.JButton();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
        setTitle("FTP Server");

        btnServer.setText("Start Server");
        btnServer.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                btnServerActionPerformed(evt);
            }
        });

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(78, 78, 78)
                .addComponent(btnServer)
                .addContainerGap(96, Short.MAX_VALUE))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
                .addContainerGap(52, Short.MAX_VALUE)
                .addComponent(btnServer, javax.swing.GroupLayout.PREFERRED_SIZE, 33, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addGap(38, 38, 38))
        );

        pack();
    }// </editor-fold>






    private void btnServerActionPerformed(java.awt.event.ActionEvent evt) {
       
        new Thread (this).start();

    }



    public void run(){

        waitForConnection();
    }



public void waitForConnection(){
            try{
                ServerSocket ss = new ServerSocket(5555);

                    while(true){
                        Socket soc = ss.accept();
                        JOptionPane.showMessageDialog(null, "I got a connection!");
                        System.out.println("Connected from: "+ soc.getInetAddress().getHostName()+"..." );

                        new FTPServerReceiver( this, soc );
                         new Thread (this).start();

                    }
            
            }catch(Exception e){ e.printStackTrace();}

}




    public static void main(String args[]) {
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new FTPServer().setVisible(true);
            }
        });
    }

    // Variables declaration - do not modify
    private javax.swing.JButton btnServer;
    // End of variables declaration

}

Junior Poster

124 posts since Mar 2009

Reputation Points: 6

Solved Threads: 0

You start the server on the Swing event thread, and in that you wait for the connection, thus blocking the Swing thread.

Posting Genius

Moderator

6,371 posts since Apr 2008

Reputation Points: 2,130

Solved Threads: 1,073

Yes,in the waitForConnection, it was a mistake.

But " start the server on the Swing event thread", you mean on the button?

Junior Poster

124 posts since Mar 2009

Reputation Points: 6

Solved Threads: 0

When you have GUI applications, they usually should run on the Event Dispatch Thread . The EDT is what James is talking about when he says the Swing thread. Since you are waiting for a connection on the EDT, you are blocking the thread, since a Thread can only do one task at once. (Think of it like this: when you run any old program, the code executes in order, so the later code has to wait for the earlier code to execute). If you read the first page of the link, you'll gain a better understanding of the event dispatch thread. Also, there is a link in there on the first page to "memory consistency errors". I personally think it is interesting, you may want to check that out also, although it is slightly off topic.

BestJewSinceJC

Posting Maven

2,772 posts since Sep 2008

Reputation Points: 874

Solved Threads: 354

Hello ... thanks for the answer, i read it but still can't solve the problem, its not working when I removed the tread from the constructor.

The message "OK Houston" does not appears which means that the blocking situation is over there.

Thanks in advance.

Junior Poster

124 posts since Mar 2009

Reputation Points: 6

Solved Threads: 0

Without an up-to-date code listing there's not a lot I can do, but...
Maybe you should take a few moments to clarify your architecture in terms of its threading. You need 3+ threads, (1) The "swing" or "EDT" thread where you do all your user interface stuff. (2) The server thread where you wait for new connections and (3) the connection handler thread(s) that you create to handle each connection as it's made.
So in your main(...) method I would expect to see a call to set up the GUI (which if you want to be pedantic you should schedule on the Swing thread, but few people would bother), and a new Thread to start the server. Judging by the code you posted, I suspect you may be getting problems because you have mixed the server code in with the GUI code - they really should be separate.

Posting Genius

Moderator

6,371 posts since Apr 2008

Reputation Points: 2,130

Solved Threads: 1,073

Hello,
I am sending you the modified one, please put a comment for me to understand this.

Thanks in advance.

package ignisftpv20;

import javax.swing.JFileChooser;
import java.io.*;
import java.net.*;
import javax.swing.JOptionPane;

public class FTPClient extends javax.swing.JFrame implements Runnable {




    
JFileChooser fileChooser = new JFileChooser();
File fileUpload;
ObjectInputStream input;
ObjectOutputStream output;



    FileInputStream fis;
    FileOutputStream fout;

    File file;







    public FTPClient() {
        initComponents();
       
     


    }









    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">                          
    private void initComponents() {

        btnBrowse = new javax.swing.JButton();
        btnSend = new javax.swing.JButton();
        btnConnect = new javax.swing.JButton();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
        setTitle("FTP Client");

        btnBrowse.setText("Browse");
        btnBrowse.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                btnBrowseActionPerformed(evt);
            }
        });

        btnSend.setText("Send File");
        btnSend.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                btnSendActionPerformed(evt);
            }
        });

        btnConnect.setText("Connect");
        btnConnect.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                btnConnectActionPerformed(evt);
            }
        });

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(91, 91, 91)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addComponent(btnSend)
                    .addComponent(btnBrowse)
                    .addComponent(btnConnect))
                .addContainerGap(107, Short.MAX_VALUE))
        );

        layout.linkSize(javax.swing.SwingConstants.HORIZONTAL, new java.awt.Component[] {btnBrowse, btnConnect, btnSend});

        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(65, 65, 65)
                .addComponent(btnConnect)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                .addComponent(btnBrowse)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addComponent(btnSend, javax.swing.GroupLayout.PREFERRED_SIZE, 35, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addContainerGap(113, Short.MAX_VALUE))
        );

        layout.linkSize(javax.swing.SwingConstants.VERTICAL, new java.awt.Component[] {btnBrowse, btnConnect, btnSend});

        java.awt.Dimension screenSize = java.awt.Toolkit.getDefaultToolkit().getScreenSize();
        setBounds((screenSize.width-281)/2, (screenSize.height-327)/2, 281, 327);
    }// </editor-fold>                        











//browse
    private void btnBrowseActionPerformed(java.awt.event.ActionEvent evt) {                                          
        int flag = fileChooser.showOpenDialog(FTPClient.this);

        if (flag == JFileChooser.APPROVE_OPTION) {
            fileUpload = fileChooser.getSelectedFile();

        }



}                                         



//connect
    private void btnConnectActionPerformed(java.awt.event.ActionEvent evt) {                                           

        connectToServer();


    }                                          


    
    
//send file
    private void btnSendActionPerformed(java.awt.event.ActionEvent evt) {                                        

           new Thread(this).start();
    }                                       


    public static void main(String args[]) {
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new FTPClient().setVisible(true);
            }
        });
    }


public void run(){
        connectToServer();
        sendBytes();

}


public void connectToServer(){

           try{
                Socket s = new Socket ("127.0.0.1" , 5555);
                input = new ObjectInputStream(s.getInputStream());
                output = new ObjectOutputStream(s.getOutputStream());
                JOptionPane.showMessageDialog(null, "OK Houston");
            }catch(Exception e){e.printStackTrace();}
}





public void sendBytes(){
        try{
            fis = new FileInputStream(fileUpload.getName());


            byte[] buffer = new byte[1024];
            int bytes = 0;

            while((bytes = fis.read(buffer))!=-1)
            {
                output.write(buffer,0,bytes);

            }




        }catch(Exception e){e.printStackTrace();}

}
    

    // Variables declaration - do not modify                     
    private javax.swing.JButton btnBrowse;
    private javax.swing.JButton btnConnect;
    private javax.swing.JButton btnSend;
    // End of variables declaration                   

}

package ignisftpv20;

import java.net.*;
import java.io.*;
import javax.swing.JOptionPane;


public class FTPServer extends javax.swing.JFrame implements Runnable {





    public FTPServer() {
        initComponents();
        new Thread (this).start();
    }



    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">                          
    private void initComponents() {

        btnServer = new javax.swing.JButton();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
        setTitle("FTP Server");

        btnServer.setText("Start Server");
        btnServer.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                btnServerActionPerformed(evt);
            }
        });

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(78, 78, 78)
                .addComponent(btnServer)
                .addContainerGap(96, Short.MAX_VALUE))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
                .addContainerGap(52, Short.MAX_VALUE)
                .addComponent(btnServer, javax.swing.GroupLayout.PREFERRED_SIZE, 33, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addGap(38, 38, 38))
        );

        pack();
    }// </editor-fold>                        






    private void btnServerActionPerformed(java.awt.event.ActionEvent evt) {                                          
       
        

    }                                         



    public void run(){

        waitForConnection();
    }



public void waitForConnection(){
            try{
                ServerSocket ss = new ServerSocket(5555);

                    while(true){
                        Socket soc = ss.accept();
                        JOptionPane.showMessageDialog(null, "I got a connection!");
                        System.out.println("Connected from: "+ soc.getInetAddress().getHostName()+"..." );

                        new FTPServerReceiver( this, soc );
                      

                    }
            
            }catch(Exception e){ e.printStackTrace();}

}




    public static void main(String args[]) {
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new FTPServer().setVisible(true);
            }
        });
    }

    // Variables declaration - do not modify                     
    private javax.swing.JButton btnServer;
    // End of variables declaration                   

}




<pre><code>package ignisftpv20;

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

public class FTPServerReceiver implements Runnable{


    FTPServer ftpServer;
    Socket thesocket;
    Byte bt;
    ObjectInputStream input;
    FileOutputStream fout;

    String directoryName = &quot;C:/Documents and Settings/Host Intruder/Desktop/Complete Download&quot;;




    public FTPServerReceiver(FTPServer ftpServer, Socket s){

        this.ftpServer = ftpServer;
        this.thesocket = s;
        new Thread( this ).start();
    }

//read and write file
    public void run(){

        try{
            while(true){


            input = new ObjectInputStream(thesocket.getInputStream());
            byte[] buffer = new byte[1024];
            int bytes = 0;
            
            //input.read(buffer,0,bytes);

            File f = new File(directoryName,&quot;file1&quot;);
            fout = new FileOutputStream(f);


            fout.write(input.read(buffer,0,bytes));







            }

        }catch(Exception e){e.printStackTrace();}



    }
}</code></pre>

Junior Poster

124 posts since Mar 2009

Reputation Points: 6

Solved Threads: 0

Don't have time to read all code now, but it looks like you're still starting the server in the Swing thread!

Posting Genius

Moderator

6,371 posts since Apr 2008

Reputation Points: 2,130

Solved Threads: 1,073

Thanks for the answer but where James. You mean here:

public FTPServer() {
        initComponents();
        new Thread (this).start();
    }

should be like this:

public FTPServer() {
        initComponents();
        //remove
    }

I have tried but its still not working.

Junior Poster

124 posts since Mar 2009

Reputation Points: 6

Solved Threads: 0

(sorry man, need to go offline now, will get back tomorrow with any luck)

Posting Genius

Moderator

6,371 posts since Apr 2008

Reputation Points: 2,130

Solved Threads: 1,073

Its OK ... thanks.

Junior Poster

124 posts since Mar 2009

Reputation Points: 6

Solved Threads: 0

fyi
www.searchjava.org

aleb

Newbie Poster

1 post since Apr 2009

Reputation Points: 10

Solved Threads: 1

Thanks for the info, but my problem is still unsolved.. can't get it to work.

Junior Poster

124 posts since Mar 2009

Reputation Points: 6

Solved Threads: 0

I can't add much to what I said in post 9. I would separate the GUI, the server, and the connection handler into 3 classes, and make sure each is started in its own thread. This really looks like the code "just grew" to the point where it's too hard to work with, you have to go back and do a bit of design!

Posting Genius

Moderator

6,371 posts since Apr 2008

Reputation Points: 2,130

Solved Threads: 1,073

Model View Controller

. . .

BestJewSinceJC

Posting Maven

2,772 posts since Sep 2008

Reputation Points: 874

Solved Threads: 354

Okie .. thanks for the answers James, I will work it out and let you know if I am having any problems, thanks for the info BJSJC. ;)

Junior Poster

124 posts since Mar 2009

Reputation Points: 6

Solved Threads: 0

Thanks a lot James, I followed your instructions and its working fine. I've just separated the user interface from the business logic. But still can't understand the logic, I will not mark this thread as solve yet as I got some questions.

Thanks a lot.