Java COM Port, Threads und Swing

package test;

public interface MailBoxListener {

    public void newMessageArived(String message);

}

import java.util.ArrayList;

import java.util.List;

import javax.swing.SwingUtilities;

public class Mailbox {

    private List<MailBoxListener> listener = new ArrayList<MailBoxListener>();

    /**

     * @param listener

     *            Listener welcher benachrichtigt werden soll wen eine neue

     *            Nachricht eintrifft.

     */

    public void addListener(MailBoxListener listener) {

        this.listener.add(listener);

    }

    /**

     * benachrichtigt alle Listener über eine neue Nachricht

     * 

     * @param message

     */

    protected void fireNewMessageArived(final String message) {

        if (SwingUtilities.isEventDispatchThread()) {

            //Wir sind schon im Event Thread

            notifyAllListeners(message);

        } else {

            //wir führen die Aktion im Event Thread aus

            SwingUtilities.invokeLater(new Runnable() {

                @Override

                public void run() {

                    notifyAllListeners(message);

                }

            });

        }

    }

    private void notifyAllListeners(String message) {

        for (MailBoxListener l : listener) {

            l.newMessageArived(message);

        }

    }

}

import javax.swing.SwingUtilities;

public class GUIClass implements MailBoxListener {

    public static void main(String[] args) {

        SwingUtilities.invokeLater(new Runnable() {

            @Override

            public void run() {

                GUIClass gclass = new GUIClass();

                gclass.createGUI();

            }

        });

    }

    protected void createGUI() {

        //Do somethin usefull

        Mailbox mailnew = new Mailbox();

        mailnew.addListener(this);

    }

    @Override

    public void newMessageArived(String message) {

        //do something with the Message

    }

}

import java.util.Date;

public class RS232MailBox extends Mailbox implements Runnable {

    public RS232MailBox() {

        //einen Thread für uns starten

        new Thread(this).start();

    }

    @Override

    public void run() {

        while (true) {

            String message = String.valueOf(System.currentTimeMillis() + " " + new Date());

            fireNewMessageArived(message);

            try {

                Thread.sleep(2000);

            } catch (InterruptedException e) {

            }

        }

    }

    public synchronized void sendMessage(String messageToSend) {

        //Message über RS232 senden

    }

}

protected void createGUI() {

    //Do somethin usefull

    RS232MailBox mailnew = new RS232MailBox();

    mailnew.addListener(this);

    mailnew.sendMessage("Hallo Ihr da draussen!");

}

        CommPortIdentifier portIdentifier = CommPortIdentifier.getPortIdentifier(portName);

        if (portIdentifier.isCurrentlyOwned()) {

            throw new RuntimeException("Port in use!");

        } else {

            // points who owns the port and connection timeout

            SerialPort serialPort = (SerialPort) portIdentifier.open("RS232Communicator", 2000);

            // setup connection parameters

            serialPort.setSerialPortParams(baudrate, SerialPort.DATABITS_8, SerialPort.STOPBITS_1, SerialPort.PARITY_NONE);

            // setup serial port writer

            out=serialPort.getOutputStream();

            serialPort.disableReceiveTimeout();

            in = serialPort.getInputStream();

        }