Ciao sono nuova di questo sito. Volevo cheiedere un'aiutino per un progetto. Devo creare una chat java UDP pear to pear tra almeno tre diversi computer.il problema principale è che i pacchetti non vengono scambiati e quindi io leggo i messaggi ma gli altri nn leggono i miei. qualcuno mi può aiutare a capire dove sbaglio?
.qui il codice: (SPEZZATO IN DUE MES PERCHE' IL SITO NN ME LO FA CARICARE TUTTO!)

codice:
/*
 * NewJFrameChat.java
 *
 * Created on 15-feb-2012, 13.32.51
 */
package chatp2p;

import java.net.*;
/**
 *
 * @author Elena
 */
public class NewJFrameChat extends javax.swing.JFrame {
    
    String username;
    Boolean isConnected = false;
    MulticastSocket socket;
    InetAddress gruppo;
    DatagramPacket pack;
    String message;

    /** Creates new form NewJFrameChat */
    public NewJFrameChat() {
        initComponents();
    }
    
    public class IncomingReader implements Runnable{

        public void run() {
            String stream;
            String[] data;
            String connect = "Connect", disconnect = "Disconnect", chat = "Chat";
            DatagramPacket p;
            byte buffer[] = new byte [1000];
            try 
            {
                while (isConnected == true)
                {   
                    p = new DatagramPacket(buffer,buffer.length);
                    socket.receive(p);
                    stream = new String(p.getData(), 0, p.getLength());            
                    /*data = stream.split("¥");
                     * 

                     if (data[2].equals(chat)) 
                     {
                        chatArea.append(data[0] + ": " + data[1] + "\n");
                     } 
                     if (data[2].equals(connect))
                     {  
                        chatArea.removeAll();
                        chatArea.append(data[0]+" si è unito alla conversazione.\n");
                        userslistArea.append(data[0]+"\n");
                     }
                     if (data[2].equals(disconnect)) 
                     {
                        chatArea.append(data[0]+" è uscito dalla conversazione");
                     }*/
                     chatArea.append(stream+"\n");
                 }
                 
              }
           catch(Exception e) 
           {
               chatArea.append("Errore: "+e.toString()+".\n");
           }
        }
    }

    public void ListenThread() 
    {
         Thread IncomingReader = new Thread(new IncomingReader());
         IncomingReader.start();
    }
    
    public void inviomessconnessione (String u)
    {
        String m;
        byte buff[] = new byte[1000];
        try
        {
            m = (u+": è connesso.\n");
            buff = m.getBytes();
            pack = new DatagramPacket(buff,buff.length,gruppo,5000);
            socket.send(pack);
        }
        catch(Exception e)
        {
            chatArea.append("Errore1:"+e.toString()+".\n");
        }
    }
    public void inviomessdisconnessione(String u)
    {
        String m;
        byte buff[]= new byte[1000];
        try
        {
            m = (u+": si è disconnesso.\n");
            buff = m.getBytes();
            pack = new DatagramPacket(buff,buff.length,gruppo,5000);
            socket.send(pack);
        }
        catch(Exception e)
        {
            //chatArea.append("Errore2:"+e.toString()+".\n");
        }
    }

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

        connectButton = new javax.swing.JButton();
        jButton1 = new javax.swing.JButton();
        jLabel1 = new javax.swing.JLabel();
        userField = new javax.swing.JTextField();
        jScrollPane1 = new javax.swing.JScrollPane();
        chatArea = new javax.swing.JTextArea();
        jScrollPane2 = new javax.swing.JScrollPane();
        userslistArea = new javax.swing.JTextArea();
        jLabel2 = new javax.swing.JLabel();
        jScrollPane3 = new javax.swing.JScrollPane();
        messArea = new javax.swing.JTextArea();
        sentButton = new javax.swing.JButton();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

        connectButton.setText("Connetti");
        connectButton.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                connectButtonActionPerformed(evt);
            }
        });

        jButton1.setText("Disconnetti");
        jButton1.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton1ActionPerformed(evt);
            }
        });

        jLabel1.setText("Username:");

        chatArea.setColumns(20);
        chatArea.setEditable(false);
        chatArea.setLineWrap(true);
        chatArea.setRows(5);
        jScrollPane1.setViewportView(chatArea);

        userslistArea.setColumns(20);
        userslistArea.setEditable(false);
        userslistArea.setRows(5);
        jScrollPane2.setViewportView(userslistArea);

        jLabel2.setHorizontalAlignment(javax.swing.SwingConstants.CENTER);
        jLabel2.setText("Utenti connessi");

        messArea.setColumns(20);
        messArea.setRows(5);
        jScrollPane3.setViewportView(messArea);

        sentButton.setText("Invia");
        sentButton.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                sentButtonActionPerformed(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()
                .addContainerGap()
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addGroup(layout.createSequentialGroup()
                        .addComponent(jScrollPane3, javax.swing.GroupLayout.PREFERRED_SIZE, 494, javax.swing.GroupLayout.PREFERRED_SIZE)
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                        .addComponent(sentButton, javax.swing.GroupLayout.DEFAULT_SIZE, 105, Short.MAX_VALUE))
                    .addGroup(layout.createSequentialGroup()
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING, false)
                            .addComponent(jScrollPane1, javax.swing.GroupLayout.Alignment.LEADING)
                            .addGroup(javax.swing.GroupLayout.Alignment.LEADING, layout.createSequentialGroup()
                                .addComponent(jLabel1, javax.swing.GroupLayout.PREFERRED_SIZE, 52, javax.swing.GroupLayout.PREFERRED_SIZE)
                                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                                .addComponent(userField, javax.swing.GroupLayout.PREFERRED_SIZE, 153, javax.swing.GroupLayout.PREFERRED_SIZE)
                                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                                .addComponent(connectButton, javax.swing.GroupLayout.PREFERRED_SIZE, 82, javax.swing.GroupLayout.PREFERRED_SIZE)
                                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                                .addComponent(jButton1)))
                        .addGap(18, 18, 18)
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
                            .addComponent(jLabel2, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                            .addComponent(jScrollPane2, javax.swing.GroupLayout.DEFAULT_SIZE, 188, Short.MAX_VALUE))))
                .addContainerGap())
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addContainerGap()
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jLabel1)
                    .addComponent(userField, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addComponent(connectButton)
                    .addComponent(jButton1)
                    .addComponent(jLabel2))
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING, false)
                    .addComponent(jScrollPane2, javax.swing.GroupLayout.Alignment.LEADING)
                    .addComponent(jScrollPane1, javax.swing.GroupLayout.Alignment.LEADING, javax.swing.GroupLayout.DEFAULT_SIZE, 273, Short.MAX_VALUE))
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 11, Short.MAX_VALUE)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
                    .addComponent(sentButton, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                    .addComponent(jScrollPane3))
                .addContainerGap())
        );

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