Please help me kill this java thread..... code example

I am using a JVM for a mobile device based on java 1.4, ~old I know, but it=
 is what I must use.

I am creating a simple swing application with a gui and a barcode laser sca=
nner api. I place the swing gui thread in the AWT-EventQueue, and then I pl=
ace barcode scanner code in a worker thread to feed the gui scanned item co=
des. Problem is, that when I click exit on the gui, ONLY the gui shuts down=
.. I can't seem to kill the worker thread. Have a look:

public class Main extends javax.swing.JFrame implements ActionListener, Sca=
nnerListener, ItemListener, KeyListener {
   Scanner scanner;

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

 public Main() {
         //display GUI - a simple field to display the item number when the
         // barcode scanner trigger is pressed, and a exit button to close =
the app
        initComponents();
        // launch the scanner code to feed the gui scanned items
        worker = new Runnable()
                           {
                              public void run()
                              {
                                 try
                                 {
                                  //a while loop to scan and wait
                                   launchScanner();
                                 }
                                 catch (Exception e) { =
          }
                            };
                            scannerThread = new Thread(worker);
                            scannerThread.start();
    }

  private void shutdown(java.awt.event.ActionEvent evt) { =
        
          //this will shutdown the gui when the exit button is pressed. BUT=
 how do I kill the scanner thread?
        System.exit(0);
    }