A clear workaround for JComboBox bug 4199622 please.

Question

Hi,
I'm writing a project management software where you assign a project leader to a project via combo box and in the same step this user must be added to the team member list. Now look what happened! When I open the combo and navigate via arrow keys all project leaders are added just because they are highlighted. This is very funny but I need only 1 project leader, that which is finally selected by the user. So I've spent several hours looking for a solution and find this amazing bug http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4199622. So regarding JComboBox since 1998 you dont have a way to identify a final selection, is this true (I'm using java 1.6 already)? Anyway, I applied
projectLeadC.putClientProperty("JComboBox.isTableCellEditor", Boolean.TRUE);
and now finally I can make a difference by receiving a new action "comboBoxEdited"
if (event.getActionCommand().equals("comboBoxEdited") && !item.equals(oldItem)) {
pushMember(item);
So now keyboar navigation is ok. But now how can I identify a selection commited by mouse click????? All I get is "comboBoxChanged" but both keyboard and mouse based selections issue this command, so I never know if an item was selected by mouse. I'd need "comboBoxEdited" issued by click or even better something like "CommitedByMouseClick". So can someone help me find a solution, preferably by subclassing JComboBox and fixing the action commands (I dont want to use itemSelectionChange listeners or other listeners just because of this, I dont care which item is selected before commiting, I just care for the action)? Note also, that if my combo is in a table this issue is not that severe, because I can call stopCellEditing on the table which issues a "comboBoxEdited" command.
Thanks for the help,
Marton Bokor

Answer 1

You could use a popup listener to identify the final selection. The popup listener will store the previous selection, and everytime the popup is made invisible you can check whether the new selection is different from the previous selection. If it is, then you notify whoever you need to notify. Example program,
import javax.swing.*;
import javax.swing.event.PopupMenuListener;
import javax.swing.event.PopupMenuEvent;
public class Tester {
    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                new Tester();
    JComboBox theBox;
    public Tester() {
        JFrame frame = new JFrame();
        theBox = new JComboBox(new String[]{"One","Two","Three"});
        theBox.addPopupMenuListener(new FinalSelectionListener());
        frame.setContentPane(theBox);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.pack();
        frame.setVisible(true);
    private class FinalSelectionListener implements PopupMenuListener {
        private Object oldSelectedItem;
        public void popupMenuWillBecomeInvisible(PopupMenuEvent e) {
            Object newSelectedItem = theBox.getSelectedItem();
            if(newSelectedItem != oldSelectedItem) {
                oldSelectedItem = newSelectedItem;
                selectionChanged(newSelectedItem);
        public void popupMenuWillBecomeVisible(PopupMenuEvent e) {}
        public void popupMenuCanceled(PopupMenuEvent e) {}
    private void selectionChanged(Object changedTo) {
        System.out.println("The selection was changed to: " + changedTo);
}This way new selections can be made only when the combo box popup is closed. Hence it will still work with the mouse, and it won't have the action event problem mentioned in the bug.