Chat socket e Threads?

Estou a criar um um programa chat no java, que tenho que usar o Scket e Threads, mais no momento que inicializo no programa os usuario não conseguem se comunicar

// Essa é a classe dos clientes..
package social;

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.PrintStream;
import java.io.PrintWriter;
import java.net.Socket;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.JOptionPane;
import social.servidor.TrataThread;

public class TelaPrincipal extends javax.swing.JFrame {

    private static PrintStream sockOut;
    private static Socket sock;
    // private static PrintStream sockOut;
    private static Scanner sockIn;
    private String msg = "";

    public TelaPrincipal() {
        conexao();

        initComponents();
    }

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

        jPanel1 = new javax.swing.JPanel();
        jSeparator1 = new javax.swing.JSeparator();
        jSeparator2 = new javax.swing.JSeparator();
        jTextField1 = new javax.swing.JTextField();
        jScrollPane1 = new javax.swing.JScrollPane();
        jList1 = new javax.swing.JList();
        jPanel2 = new javax.swing.JPanel();
        jScrollPane2 = new javax.swing.JScrollPane();
        msg_area = new javax.swing.JTextPane();
        msg_txt = new javax.swing.JTextField();
        jbtenviar = new javax.swing.JButton();
        jPanel4 = new javax.swing.JPanel();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
        setResizable(false);

        jPanel1.setBackground(new java.awt.Color(254, 254, 254));

        jList1.setModel(new javax.swing.AbstractListModel() {
            String[] strings = { "Item 1", "Item 2", "Item 3", "Item 4", "Item 5" };
            public int getSize() { return strings.length; }
            public Object getElementAt(int i) { return strings[i]; }
        });
        jScrollPane1.setViewportView(jList1);

        javax.swing.GroupLayout jPanel1Layout = new javax.swing.GroupLayout(jPanel1);
        jPanel1.setLayout(jPanel1Layout);
        jPanel1Layout.setHorizontalGroup(
            jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addComponent(jSeparator1)
            .addComponent(jSeparator2)
            .addComponent(jScrollPane1)
            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jPanel1Layout.createSequentialGroup()
                .addContainerGap()
                .addComponent(jTextField1, javax.swing.GroupLayout.DEFAULT_SIZE, 256, Short.MAX_VALUE)
                .addContainerGap())
        );
        jPanel1Layout.setVerticalGroup(
            jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(jPanel1Layout.createSequentialGroup()
                .addContainerGap()
                .addComponent(jTextField1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addComponent(jSeparator1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addComponent(jScrollPane1, javax.swing.GroupLayout.DEFAULT_SIZE, 398, Short.MAX_VALUE)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addComponent(jSeparator2, javax.swing.GroupLayout.PREFERRED_SIZE, 10, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addGap(32, 32, 32))
        );

        jPanel2.setBackground(new java.awt.Color(254, 254, 254));

        jScrollPane2.setViewportView(msg_area);

        jbtenviar.setText("Enviar");
        jbtenviar.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jbtenviarActionPerformed(evt);
            }
        });

        javax.swing.GroupLayout jPanel2Layout = new javax.swing.GroupLayout(jPanel2);
        jPanel2.setLayout(jPanel2Layout);
        jPanel2Layout.setHorizontalGroup(
            jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(jPanel2Layout.createSequentialGroup()
                .addContainerGap()
                .addGroup(jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
                    .addComponent(jScrollPane2, javax.swing.GroupLayout.PREFERRED_SIZE, 502, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addGroup(jPanel2Layout.createSequentialGroup()
                        .addComponent(msg_txt, javax.swing.GroupLayout.PREFERRED_SIZE, 381, javax.swing.GroupLayout.PREFERRED_SIZE)
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                        .addComponent(jbtenviar, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)))
                .addContainerGap(33, Short.MAX_VALUE))
        );
        jPanel2Layout.setVerticalGroup(
            jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, jPanel2Layout.createSequentialGroup()
                .addContainerGap()
                .addComponent(jScrollPane2)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addGroup(jPanel2Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
                    .addComponent(msg_txt)
                    .addComponent(jbtenviar, javax.swing.GroupLayout.DEFAULT_SIZE, 43, Short.MAX_VALUE))
                .addContainerGap())
        );

        jPanel4.setBackground(new java.awt.Color(31, 182, 211));

        javax.swing.GroupLayout jPanel4Layout = new javax.swing.GroupLayout(jPanel4);
        jPanel4.setLayout(jPanel4Layout);
        jPanel4Layout.setHorizontalGroup(
            jPanel4Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGap(0, 0, Short.MAX_VALUE)
        );
        jPanel4Layout.setVerticalGroup(
            jPanel4Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGap(0, 56, Short.MAX_VALUE)
        );

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addComponent(jPanel1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addComponent(jPanel2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
            .addComponent(jPanel4, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
                .addComponent(jPanel4, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addComponent(jPanel1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                    .addComponent(jPanel2, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)))
        );

        setBounds(260, 120, 826, 595);
    }// </editor-fold>                        


    private void jbtenviarActionPerformed(java.awt.event.ActionEvent evt) {                                          
        // TODO add your handling code here:
        try {

            String msgout = "";

            msgout = msg_txt.getText().trim();
            msg_txt.setText("");

            msg_area.setText(msg_area.getText() + "\n" + msgout);
            sockOut.println(msgout);
            
//            String msgout = "";
//            String msgres = "";
//            msgout = msg_txt.getText().trim();
//            sockOut.println(msgout);
//            msgres = sockIn.nextLine();
//            msg_area.setText(msgres + "\n");
//            String msgout = "";
//            String msgres = "";
//
//            msgout = msg_txt.getText().trim();
//            sockOut.println(msgout);
//            
//            msgres = sockIn.nextLine();
//            
//            msg += msgres + "\n";
//            String texto;
//               
//            msg_area.setText(msg + "\n");

        } catch (Exception ex) {
        }
    }                                         

    public static void main(String args[]) {
        
        /* Set the Nimbus look and feel */
        //<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
        /* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
         * For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html 
         */
        try {
            for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
                if ("Nimbus".equals(info.getName())) {
                    javax.swing.UIManager.setLookAndFeel(info.getClassName());
                    break;
                }
            }
        } catch (ClassNotFoundException ex) {
            java.util.logging.Logger.getLogger(TelaPrincipal.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (InstantiationException ex) {
            java.util.logging.Logger.getLogger(TelaPrincipal.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (IllegalAccessException ex) {
            java.util.logging.Logger.getLogger(TelaPrincipal.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (javax.swing.UnsupportedLookAndFeelException ex) {
            java.util.logging.Logger.getLogger(TelaPrincipal.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        }
        //</editor-fold>
        /* Create and display the form */

        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {

                new TelaPrincipal().setVisible(true);

            }
        });

    }

    public static void conexao() {
        try {
            String linha;
            sock = new Socket("127.0.0.1", 6000);
            sockOut = new PrintStream(sock.getOutputStream());
            sockIn = new Scanner(sock.getInputStream());
            new Thread(new TrataThread(sock)).start();
        } catch (IOException ex) {
            Logger.getLogger(TelaPrincipal.class.getName()).log(Level.SEVERE, null, ex);
        }
    }


    // Variables declaration - do not modify                     
    private javax.swing.JList jList1;
    private javax.swing.JPanel jPanel1;
    private javax.swing.JPanel jPanel2;
    private javax.swing.JPanel jPanel4;
    private javax.swing.JScrollPane jScrollPane1;
    private javax.swing.JScrollPane jScrollPane2;
    private javax.swing.JSeparator jSeparator1;
    private javax.swing.JSeparator jSeparator2;
    private javax.swing.JTextField jTextField1;
    private javax.swing.JButton jbtenviar;
    private static javax.swing.JTextPane msg_area;
    private static javax.swing.JTextField msg_txt;
    // End of variables declaration                   
}


//Essa aqui é a classe do servidor
package social.servidor;

import java.io.IOException;
import java.io.PrintStream;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
import social.TelaPrincipal;

/**
 *
 * @author ninja
 */
public class Servidor {

    private static final int Port = 6000;

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        List<Socket> so = new ArrayList<>();
        List<PrintStream> men = new ArrayList<>();

        ServerSocket server = null;

        try {

            server = new ServerSocket(Port);
            while (true) {
                Socket cli = server.accept();
                so.add(cli);
                new Thread(new TrataThread(cli)).start();
                PrintStream p = new PrintStream(cli.getOutputStream());
                Scanner sc = new Scanner(cli.getInputStream());
                men.add(p);
//   TrataThread t = new TrataThread(cli, so);
                //   t.setSo(so);
                // t.start();
            }

        } catch (Exception e) {
        }

    }

}

//Esse é a classe para tratar as Threads
/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package social.servidor;

import java.io.IOException;
import java.io.PrintStream;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
 *
 * @author ninja
 */
public class TrataThread extends Thread {

    List<Socket> so;
    List<PrintStream> men = new ArrayList();
    private Socket sock;
    PrintStream pr = null;
    private String cmd = null;
    Scanner sc;

    public TrataThread(Socket sock) {
        this.sock = sock;
        //this.so = so;
        try {
            sc = new Scanner(sock.getInputStream());
        } catch (IOException ex) {
            Logger.getLogger(TrataThread.class.getName()).log(Level.SEVERE, null, ex);
        }

    }

    public void setSo(List<Socket> so) {
        this.so = so;
        criarPrint();

    }

    @Override
    public void run() {
        try {

            //    pr = new PrintStream(sock.getOutputStream());
            while (true) {

                cmd = sc.nextLine();

                System.out.println("Recebido>> " + cmd);
                EnviarTodos(cmd);
                men.add(pr);
            }
        } catch (Exception ex) {
        }
    }

    private void criarPrint() {
        for (Socket s : so) {
            try {
                //PrintStream p = new PrintStream(s.getOutputStream());
                sc = new Scanner(sock.getInputStream());
            } catch (IOException ex) {
                Logger.getLogger(TrataThread.class.getName()).log(Level.SEVERE, null, ex);
            }
        }

    }

    public void EnviarTodos(String texto) {

        for (PrintStream w : men) {
            try {
                w.println(texto);
                w.flush();

            } catch (Exception e) {

            }
        }
    }

}

Preciso de ajuda mesmo jatentei de varias formas