Timer, Threads, TableModels, and adding a row. Need Help

Question

Ok so essentially my problem is i guess pretty simple. Skip this next part to get to the problem.
My project: I'm simply building a bell server, pretty simple. Plays a sound/recording at a specific time. It also however, grabs the times off an RSS feed; additionally it plays announcements and bells, it also automatically recalculates times if you adjust one, it ensures that all bells/announcements do not overlap; (theres some other qualities but they don't matter).
My problem: I have essentially a few different classes in my project however there are only 2 that are giving me great amounts of grief at the moment. First is my main, it calls/sets up the GUI using a JFrame, I am using DefaultTableModel as my table model for a regular JTable. The main also creates an object called SchedManager, this object is what does all of the organizing, keeping the times up and such; the SchedManager object is also a timer task which is scheduled to run every 5 seconds, every time it runs it does a few things but primarily, it checks its Vector of SchedItems to make sure none overlap and such, after that, it calls a public method of TestMain's. This method simply calls a public method of SchedManger's that returns a 2D Object array of the items, then it attempts to update the tables data by using a quick method that updates all the tables data, however obviously I may need to add a row, so I have it add a row if necessary. This is my problem though, when I call model.addRow it blows up with a nullPointerException. Heres a simplified version of my code, all this code is attempting to do is to add a row every time SubClass is ran:
TestMain.java :
import java.util.*;
import javax.swing.*;
import javax.swing.table.*;
import java.awt.*;
import java.awt.event.*;
public class TestMain extends JFrame{
    protected static Container container;
    private static JTable table;
    private static Vector data = new Vector();
    private static Vector columns = new Vector();
    public static DefaultTableModel model;
    private static SubClass sub = new SubClass();
    public static TestMain tm;
    public TestMain() {
     container = this.getContentPane();
    private static void createAndShowGUI(){
     JFrame.setDefaultLookAndFeelDecorated(true);
     JFrame frame = new JFrame("Hell's Bells");
     frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
     columns.add("Test");
     columns.add("Test2");
     GridBagLayout gridbag = new GridBagLayout();
     JPanel contentPane = new JPanel(gridbag);
     container.setLayout(gridbag);
     GridBagConstraints gbc = new GridBagConstraints();
     gbc.fill = gbc.BOTH;
     gbc.gridheight = 48;
     gbc.gridwidth = 60;
     gbc.gridx = 2;
     gbc.gridy = 13;
     gbc.weightx = .8;
     gbc.weighty = .6;     
     model = new DefaultTableModel(data,columns);
     table = new JTable(model);
     gridbag.setConstraints(table, gbc);
     container.add(table);
     JButton update = new JButton("update");//Creates a new button update
     ButtonListener updateButtonListener = new ButtonListener();//creates a new button listener
     update.addActionListener(updateButtonListener);
     container.add(update);
     frame.setContentPane(container);
     frame.setLocation(200,100);
     frame.pack();
     frame.setSize(new Dimension(750,800));
     frame.setVisible(true);
    public static void main(String[] args) {
        //Schedule a job for the event-dispatching thread:
        //creating and showing this application's GUI.
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                createAndShowGUI();
    public static void updateTable(){
     model.addRow(new Object[]{"test"});
    static class ButtonListener implements ActionListener{
     int value = 0;
     public void actionPerformed(ActionEvent e){
         String button = e.getActionCommand();
         if(button == "update"){
          System.out.println("TEST");
          model.addRow(new Object[]{"test"});
          table.setValueAt("TEST",0,0);
          if(value==3)
              table.setValueAt("TEST",0,1);
          if(value==4)
              table.setValueAt("TEST",3,0);
          if(value==5)
              table.setValueAt("TEST",2,1);
          value++;
}SubClass.java :
import java.util.*;
public class SubClass extends TimerTask{
    public static TestMain tm = new TestMain();
    public SubClass(){
     TimerTask task = this;
     Timer manager = new Timer();
     manager.schedule(task,0,5000);
    public void run(){
     //tm.model.addRow(new Object[]{"test"});
     tm.updateTable();
}Does it have something to do with JFrame? because using almost identical code but using JPanel it works fine.
All help is greatly appreciated!
Thanks In Advance,
Airplane

Answer 1

Whoops, sorry bout' that. Heres the error I receive:
Exception in thread "Timer-0" java.lang.NullPointerException
        at TestMain.updateTable(TestMain.java:81)
        at SubClass.run(SubClass.java:17)
        at java.util.TimerThread.mainLoop(Timer.java:512)
        at java.util.TimerThread.run(Timer.java:462)Heres the printStackTrace(); when i put the thread in a try/catch:
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
        at TestMain.createAndShowGUI(TestMain.java:39)
        at TestMain.access$000(TestMain.java:7)
        at TestMain$1.run(TestMain.java:80)
        at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:461)
        at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchThread.java:242)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:163)
        at
java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:157)        at
java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:149)        at
java.awt.EventDispatchThread.run(EventDispatchThread.java:110)Regards,
Airplane
Message was edited by:
Airplane