SwingUtilities throwing Null Exception

Question

I created the following class to report a bug and came across something interesting:
// Instructions to view bug
// 1) On your favorite windows operated machine (xp in my case) unlock and move your taskbar
//    so that it is along the left pane of your screen.
// 2) Run the following java program
// 3) Maximize the BugCheck window
// 4) Click on the down arrow of the combobox
// 5) You will see the combobox is not dropping to where it should and the dropdown selection text is cutoff.
package com.BugCheck;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
* This simple class will demonstrate a jcombobox being misaligned
* when selected and the user's Windows taskbar is along the LEFT
* side of the screen.
public class BugCheck extends JFrame
    public BugCheck()
        try
            jbInit();
        } catch (Exception ex)
            ex.printStackTrace();
    public static void main(String args[])
        BugCheck f = new BugCheck();
        f.setSize(new Dimension(100, 100));
        f.setVisible(true);
        try {
            UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel");
            SwingUtilities.updateComponentTreeUI(f);
        } catch (Exception e ) {
            e.printStackTrace();
    private void jbInit() throws Exception
        jComboBox1.addItem("Selection 1");
        jComboBox1.addItem("Selection 2");
        jComboBox1.addItem("Can't");
        jComboBox1.addItem("see");
        jComboBox1.addItem("this.");
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        this.setTitle("BugCheck");
        this.getContentPane().add(jComboBox1, java.awt.BorderLayout.NORTH);
    JComboBox jComboBox1 = new JComboBox();
}I got the exceptions listed below, and after some fiddling it turns out the culprit is the following line of code. When commented out, the exceptions do not happen.
this.getContentPane().add(jComboBox1, java.awt.BorderLayout.NORTH);is causing these exceptions to be thrown:
"C:\Program Files\Java\j2re1.4.2_07\bin\javaw" -classpath "H:\BugCheck\classes;C:\Program Files\Java\j2re1.4.2_07\javaws\javaws.jar;C:\Program Files\Java\j2re1.4.2_07\lib\charsets.jar;C:\Program Files\Java\j2re1.4.2_07\lib\ext\dnsns.jar;C:\Program Files\Java\j2re1.4.2_07\lib\ext\ldapsec.jar;C:\Program Files\Java\j2re1.4.2_07\lib\ext\localedata.jar;C:\Program Files\Java\j2re1.4.2_07\lib\ext\sunjce_provider.jar;C:\Program Files\Java\j2re1.4.2_07\lib\im\indicim.jar;C:\Program Files\Java\j2re1.4.2_07\lib\im\thaiim.jar;C:\Program Files\Java\j2re1.4.2_07\lib\jce.jar;C:\Program Files\Java\j2re1.4.2_07\lib\jsse.jar;C:\Program Files\Java\j2re1.4.2_07\lib\plugin.jar;C:\Program Files\Java\j2re1.4.2_07\lib\rt.jar;C:\Program Files\Java\j2re1.4.2_07\lib\sunrsasign.jar"  com.BugCheck.BugCheck
java.lang.NullPointerException
     at javax.swing.DefaultListCellRenderer.getListCellRendererComponent(Unknown Source)
     at javax.swing.plaf.basic.BasicComboBoxUI.getDisplaySize(Unknown Source)
     at javax.swing.plaf.basic.BasicComboBoxUI.getMinimumSize(Unknown Source)
     at javax.swing.plaf.basic.BasicComboBoxUI.getPreferredSize(Unknown Source)
     at javax.swing.JComponent.getPreferredSize(Unknown Source)
     at java.awt.BorderLayout.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.validateTree(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$ComponentWorkRequest.run(Unknown Source)
     at java.awt.event.InvocationEvent.dispatch(Unknown Source)
     at java.awt.EventQueue.dispatchEvent(Unknown Source)
     at java.awt.EventDispatchThread.pumpOneEventForHierarchy(Unknown Source)
     at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
     at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
     at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
     at java.awt.EventDispatchThread.run(Unknown Source)
java.lang.NullPointerException
     at javax.swing.plaf.basic.BasicComboBoxUI.isPopupVisible(Unknown Source)
     at javax.swing.plaf.basic.BasicComboBoxUI.paintCurrentValue(Unknown Source)
     at javax.swing.plaf.basic.BasicComboBoxUI.paint(Unknown Source)
     at javax.swing.plaf.ComponentUI.update(Unknown Source)
     at javax.swing.JComponent.paintComponent(Unknown Source)
     at javax.swing.JComponent.paint(Unknown Source)
     at javax.swing.JComponent.paintWithOffscreenBuffer(Unknown Source)
     at javax.swing.JComponent.paintDoubleBuffered(Unknown Source)
     at javax.swing.JComponent._paintImmediately(Unknown Source)
     at javax.swing.JComponent.paintImmediately(Unknown Source)
     at javax.swing.RepaintManager.paintDirtyRegions(Unknown Source)
     at javax.swing.SystemEventQueueUtilities$ComponentWorkRequest.run(Unknown Source)
     at java.awt.event.InvocationEvent.dispatch(Unknown Source)
     at java.awt.EventQueue.dispatchEvent(Unknown Source)
     at java.awt.EventDispatchThread.pumpOneEventForHierarchy(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)Any comments?

Answer 1

Some thoughts, 1) eliminate all those unnecessary jar
files from your classpath 2) add the bin directory of
the jdk to your PATH variable and call the java
command directly for simplicity ... 3) Only include
on your classpath any jar files that you have created
for your application or 3rd party jar files. In your
example it doesn't look like you need to include any
jar files. 4) I also notice that your package name
and class name are the same. Generally package names
are lower case and Class names are upper case.
java com.bugcheck.BugCheck
None of these address the issue at hand. Although I do commend you for being nitpicky!
Suprisingly, running the same program with Java 1.4.2 b5 (the OP was done with 1.4.2 b7) gives more informaton:
[code
java.lang.NullPointerException
     at javax.swing.DefaultListCellRenderer.getListCellRendererComponent(DefaultListCellRenderer.java:80)
     at javax.swing.plaf.basic.BasicComboBoxUI.getDisplaySize(BasicComboBoxUI.java:1275)
     at javax.swing.plaf.basic.BasicComboBoxUI.getMinimumSize(BasicComboBoxUI.java:969)
     at javax.swing.plaf.basic.BasicComboBoxUI.getPreferredSize(BasicComboBoxUI.java:959)
     at javax.swing.JComponent.getPreferredSize(JComponent.java:1275)
     at java.awt.BorderLayout.layoutContainer(BorderLayout.java:668)
     at java.awt.Container.layout(Container.java:1020)
     at java.awt.Container.doLayout(Container.java:1010)
     at java.awt.Container.validateTree(Container.java:1092)
     at java.awt.Container.validateTree(Container.java:1099)
     at java.awt.Container.validateTree(Container.java:1099)
     at java.awt.Container.validate(Container.java:1067)
     at javax.swing.RepaintManager.validateInvalidComponents(RepaintManager.java:353)
     at javax.swing.SystemEventQueueUtilities$ComponentWorkRequest.run(SystemEventQueueUtilities.java:116)
     at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:178)
     at java.awt.EventQueue.dispatchEvent(EventQueue.java:454)
     at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchThread.java:201)
     at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:151)
     at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:145)
     at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:137)
     at java.awt.EventDispatchThread.run(EventDispatchThread.java:100)
java.lang.NullPointerException
     at javax.swing.plaf.basic.BasicComboBoxUI.isPopupVisible(BasicComboBoxUI.java:919)
     at javax.swing.plaf.basic.BasicComboBoxUI.paintCurrentValue(BasicComboBoxUI.java:1148)
     at javax.swing.plaf.basic.BasicComboBoxUI.paint(BasicComboBoxUI.java:954)
     at javax.swing.plaf.ComponentUI.update(ComponentUI.java:142)
     at javax.swing.JComponent.paintComponent(JComponent.java:541)
     at javax.swing.JComponent.paint(JComponent.java:808)
     at javax.swing.JComponent.paintWithOffscreenBuffer(JComponent.java:4787)
     at javax.swing.JComponent.paintDoubleBuffered(JComponent.java:4740)
     at javax.swing.JComponent._paintImmediately(JComponent.java:4685)
     at javax.swing.JComponent.paintImmediately(JComponent.java:4488)
     at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:410)
     at javax.swing.SystemEventQueueUtilities$ComponentWorkRequest.run(SystemEventQueueUtilities.java:117)
     at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:178)
     at java.awt.EventQueue.dispatchEvent(EventQueue.java:454)
     at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchThread.java:201)
     at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:151)
     at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:145)
     at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:137)
     at java.awt.EventDispatchThread.run(EventDispatchThread.java:100)