Cant get automatic scrolling text pane to work from other classes

Question

Hi guys, I've been creating a program that utilises JInternalFrames, one of which frames is an "event log" which is simply a Document I append text to, problem is I'm getting some strange logic errors. It works fine if it's just left alone and adds text from its internal timer method, but as soon (sometimes on 3rd or 4th call) of it's static method called 'append' it starts spewing out error message - mainly ""AWT-EventQueue-0" java.lang.NullPointerException", and stops working.
Here is my internal frame (a MyJDesktopPane component), with its internal appendText that works fine.
import java.awt.event.*;
import java.text.SimpleDateFormat;
import java.util.Date;
import javax.swing.*;
public class EventLog extends JInternalFrame {
    public EventLog() {
        super("",
                  false,      //resizable
                  false,      //closable
                  false,      //maximizable
                  true);     //iconifiable
        atp = new ELInternal();
        this.getContentPane().add(new JScrollPane(atp));
        this.setSize(200, 200);
        this.setVisible(true);
        // Add some text every second
        Timer t = new Timer(1000, new ActionListener() {
          public void actionPerformed(ActionEvent evt) {
            String timeString = fmt.format(new Date());
            atp.appendText(timeString + "\n");
          SimpleDateFormat fmt = new SimpleDateFormat("HH:mm:ss");
        t.start();
    public static void append(String in)
         try {
                   atp.appendText(in + "\n");
         } catch ( Exception e  ){}
    static ELInternal atp;
}Here is the internal panes content:
import java.awt.*;
import javax.swing.*;
import javax.swing.text.*;
public class ELInternal extends JTextPane {
  public ELInternal() {
    super();
  public ELInternal(StyledDocument doc) {
    super(doc);
  // Appends text to the document and ensure that it is visible
  public  void appendText(String text) {
    try {
      Document doc = getDocument();
      // Move the insertion point to the end
      setCaretPosition(doc.getLength());
      // Insert the text
      replaceSelection(text);
      // Convert the new end location
      // to view co-ordinates
      Rectangle r = modelToView(doc.getLength());
      // Finally, scroll so that the new text is visible
      if (r != null) {
        scrollRectToVisible(r);
    } catch (BadLocationException e) {
      System.out.println("Failed to append text: " + e);
}So every time I call "append" which another classes need to be able to call to update it's current event, It just doesn't work... ? I've been staring at this code for hours, think it's going all matrix on me.

Answer 1

Isn't this the "*new* to java" forum? I know what error messages are for, if I understood it I wouldn't be here asking the question!!!!
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
     at javax.swing.text.BoxView.updateChildSizes(Unknown Source)
     at javax.swing.text.BoxView.setSpanOnAxis(Unknown Source)
     at javax.swing.text.BoxView.layout(Unknown Source)
     at javax.swing.text.BoxView.setSize(Unknown Source)
     at javax.swing.text.BoxView.updateChildSizes(Unknown Source)
     at javax.swing.text.BoxView.setSpanOnAxis(Unknown Source)
     at javax.swing.text.BoxView.layout(Unknown Source)
     at javax.swing.text.FlowView.layout(Unknown Source)
     at javax.swing.text.BoxView.setSize(Unknown Source)
     at javax.swing.text.BoxView.updateChildSizes(Unknown Source)
     at javax.swing.text.BoxView.setSpanOnAxis(Unknown Source)
     at javax.swing.text.BoxView.layout(Unknown Source)
     at javax.swing.text.BoxView.setSize(Unknown Source)
     at javax.swing.plaf.basic.BasicTextUI$RootView.setSize(Unknown Source)
     at javax.swing.plaf.basic.BasicTextUI.getPreferredSize(Unknown Source)
     at javax.swing.JComponent.getPreferredSize(Unknown Source)
     at javax.swing.JEditorPane.getPreferredSize(Unknown Source)
     at javax.swing.ScrollPaneLayout.layoutContainer(Unknown Source)
     at java.awt.Container.layout(Unknown Source)
     at java.awt.Container.doLayout(Unknown Source)
     at java.awt.Container.validateTree(Unknown Source)
     at java.awt.Container.validate(Unknown Source)
     at javax.swing.RepaintManager.validateInvalidComponents(Unknown Source)
     at javax.swing.SystemEventQueueUtilities$ComponentWorkRequest.run(Unknown Sourc
e)
     at java.awt.event.InvocationEvent.dispatch(Unknown Source)
     at java.awt.EventQueue.dispatchEvent(Unknown Source)
     at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
     at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
     at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
     at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
     at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
     at java.awt.EventDispatchThread.run(Unknown Source)