Java 6 JComboBox Regression?

Question

Today I decided to try out my application with the Java 6 JRE. I was quite impressed until I found that the JComboBox is no longer firing action events when the user selects the same item from the list. Action events are fired in JRE 1.4 and 1.5, but it breaks in 1.6.
Here is a simple test case:
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JComboBox;
import javax.swing.JFrame;
public class ActionTest extends JFrame {
public ActionTest() {
String[] items = { "item1", "item2", "item3"};
JComboBox jComboBox = new JComboBox(items);
jComboBox.addActionListener(new ActionHandler());
getContentPane().add(jComboBox);
pack();
setVisible(true);
public static void main(String[] args) {
ActionTest actionTest = new ActionTest();
class ActionHandler implements ActionListener {
public final void actionPerformed(final ActionEvent e) {
System.out.println("Action Event Fired");
When the above code is run under java 1.4 or 1.5, an action event is fired even when the user selects the same item from the list. According to the docs this is the correct behaviour. However, when the above code is run under 1.6, no action events are fired when the user selects the same item from the list. This seems like a rather serious regression. Has anyone else experienced this?
Robert

Answer 1

After a long research and many many tries, if finallay found a workaround.
Below is a working demo.
import java.awt.Dimension;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.Serializable;
import java.util.Vector;
import javax.swing.ComboBoxModel;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.event.ListDataEvent;
import javax.swing.event.PopupMenuEvent;
import javax.swing.event.PopupMenuListener;
public class AlwaysSelectableComboBoxDemo extends JFrame {
     public static void main(String[] args) {
          AlwaysSelectableComboBoxDemo frame = new AlwaysSelectableComboBoxDemo();
          frame.setMinimumSize(new Dimension(150,50));
          frame.setVisible(true);
          frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
     public AlwaysSelectableComboBoxDemo() {
          final AlwaysSelectableComboBox combi = new AlwaysSelectableComboBox(
                                                                 new Object[]{"Item 1","Item 2", "Item 3"});
          combi.addActionListener(new ActionListener() {
               public void actionPerformed(ActionEvent ae) {
                    System.out.println("Yeah");
          combi.addPopupMenuListener(new PopupMenuListener(){
               private boolean isCanceled = false;
               private Object oldSelection = null;
               public void popupMenuCanceled(PopupMenuEvent e) {
                    isCanceled = true;
               public void popupMenuWillBecomeInvisible(PopupMenuEvent e) {
                    JComboBox comboBox = ((JComboBox)e.getSource());
                    if(!isCanceled && comboBox.getSelectedItem() == oldSelection) {
                         comboBox.contentsChanged(new ListDataEvent(e.getSource(),ListDataEvent.CONTENTS_CHANGED,0,0));
                    isCanceled = false;
               public void popupMenuWillBecomeVisible(PopupMenuEvent e) {
                    oldSelection = ((JComboBox)e.getSource()).getSelectedItem();
          this.add(combi);
     public class AlwaysSelectableComboBox extends JComboBox implements     Serializable
          public AlwaysSelectableComboBox(ComboBoxModel aModel){
               super(aModel);
          public AlwaysSelectableComboBox(final Object items[]) {
               super(items);
          public AlwaysSelectableComboBox(Vector items) {
               super(items);
         public AlwaysSelectableComboBox() {
              super();
         public void contentsChanged(ListDataEvent e) {
             selectedItemReminder = null;
             super.contentsChanged(e);
}