Re: Trying to get JComboBox to "repopulate" with increased java.util.Vector

Nigel Wade <>
Fri, 09 Feb 2007 16:27:05 +0000
<eqi7cp$dbi$> wrote:

On Feb 8, 9:02 pm, Knute Johnson <>
wrote: wrote:

On Feb 8, 5:31 pm, Knute Johnson <>
wrote: wrote:

I have a JFrame with two JPanels

 > >>> Top JPanel p1 contains:

1 JLabel that never changes
1 JComboBox that is populated by dynamic values found in
1 JButton
If you press that JButton this method fires off:
     * Process new {@link} request
    protected void processURL() {
        System.out.println("Your new URL is " +
webAddressBox.getSelectedItem().toString()); // webAddress is
        SimpleBrowser.hasEnteredAdditionalURL = true;
        setURLPath(webAddressBox.getSelectedItem().toString()); //
        try {
URL(webAddressBox.getSelectedItem().toString())); // WORKS
        } catch (Exception e) {}
        generateWebBrowser(); // WORKS - CREATES
org.jdesktop.jdic.browser.WebBrowser each time you enter in a URL in
JComboBox and press JButton
        webAddressBox = null;
        generateJComboBox(); // THIS SHOULD CREATE A BRAND NEW
     * Populate {@link #webAddressBox} optionally using {@link
    private void generateJComboBox() {
        if (historyURLVector != null && historyURLVector.size() > 0) {
            webAddressBox = new JComboBox(historyURLVector);
        } else {
            webAddressBox = new JComboBox();
        if (!SimpleBrowser.hasAddedInitialURL && getURL() != null) {
        } else if (!SimpleBrowser.hasAddedInitialURL && getURLPath() !
= null) {
        if (getScreenWidth() == 0)
        Dimension dim = new Dimension((int)(getScreenWidth() / 1.14),
                (int)(SimpleBrowser.DEFAULT_WEB_ADDRESS_BAR_HEIGHT /
When the JFrame fires up the first time, I see my top JPanel just
right with just one value in it, and the bottom JPanel with the URL
displayed. I enter another URL into the JComboBox and click the
JButton; while the bottom JPanel refreshes with a brand new URL
displayed, the top one shows ONLY the new URL; I want to display a
total dropdown of ALL URLS you have ever entered from the first until
now as a "historyURLVector" so to speak. The values in
java.util.Vector accurately reflect that you have now 2 URLS for
example instead of just the initial 1 URL, but the JCombBox only shows
1 URL when you want to see all of them.
Best way to understand this would be very easy: just like your address
bar in your browser should show multiple URLs, so should mine, but I
can't figure out how to do this part of it all the while having a semi-
working simple browser.

Where do you remove the old JComboBox and add the new one?

processURL() sets JComboBox webAddressBox to null; generateJComboBox()
generates a brand new JComboBox webAddressBox

You need to remove the old component and add a new component. Just
replacing the reference won't get it done.

but wouldn't that be accomplished this way:


     * Add all available panels to the {@link SimpleBrowser} (extends
{@link javax.swing.JFrame})
    public void addToFrame() {
        setLayout(new GridBagLayout());
        c = new GridBagConstraints();
        c.gridx = 0;
        c.gridy = 0;
        c.anchor = GridBagConstraints.NORTHWEST;
        add(p1, c);
        if (!SimpleBrowser.hasEnteredAdditionalURL) {
         c.gridx = 0;
         c.anchor = GridBagConstraints.CENTER;
         add(p2, c);

     * Layout {@link #p1}
    private void layoutTopPanel() {
        c = new GridBagConstraints();
        c.gridx = 0;
        c.gridy = 0;
        c.anchor = GridBagConstraints.NORTHWEST;

        p1.setLayout(new GridBagLayout());
        p1.add(new JLabel("Your URL:"), c);

        c.gridy = 0;
        c.fill = GridBagConstraints.HORIZONTAL;
        p1.add(webAddressBox, c); // ADD JComboBox

        c.gridy = 0;
        c.fill = GridBagConstraints.NONE;
        p1.add(b, c); // ADD JBUTTON
        if (getScreenWidth() <= 0)
        p1.setSize(new Dimension(getScreenWidth(),

     * Reset {@link #p1}
    private void resetTopPanel() {
        p1 = new JPanel(true);

Upon attempting this only the bottom JPanel appears upon entering a
new URL from the top JPanel; the top JPanel does not reappear

If you remove/add components I think you need to revalidate().

Do you really need to keep creating, adding and removing components? Is there a
reason that you can't just change what the existing components are displaying?

Nigel Wade, System Administrator, Space Plasma Physics Group,
            University of Leicester, Leicester, LE1 7RH, UK
E-mail :
Phone : +44 (0)116 2523548, Fax : +44 (0)116 2523555

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