Update JComboBox popupMenu

Question

I have a JComboBox with only one value in the start and have one MouseListener connected to it. When I click on the JComboBox I fill it with some new values. But the popupMenu are of the size of one element on the first click on the JComboBox. The second time all values will appear as normal. Any idea how I can make the comboBox update its popupMenu directly after I have updated its content?

Example program:

public class ComboBoxUpdate extends JFrame implements MouseListener {

    private JComboBox<String> box;
    public ComboBoxUpdate(){
        // Init
        JPanel panel = new JPanel();
        box = new JComboBox<String>();
        box.addItem("from start");

        // Add listener
        Component[] comps = box.getComponents();
        for(int i = 0; i < comps.length; i++)
            comps[i].addMouseListener(this);

        panel.add(box);
        this.add(panel);
        this.pack();
        this.setVisible(true);
    }

    @Override
    public void mouseClicked(MouseEvent e) {
        if(box.getItemCount() == 1){
            box.removeAllItems();
            box.addItem("item 1");
            box.addItem("item 2");
            box.addItem("item 3");
        }
    }

    public static void main(String[] args){
        new ComboBoxUpdate();
    }

    @Override
    public void mousePressed(MouseEvent e) {}

    @Override
    public void mouseReleased(MouseEvent e) {}

    @Override
    public void mouseEntered(MouseEvent e) {}

    @Override
    public void mouseExited(MouseEvent e) {}
}

Ricardo Cacheira · Accepted Answer · 2013-05-10T09:02:56.053

I think it's the better solution:

public class ComboBoxUpdate extends JFrame implements PopupMenuListener {

    private JComboBox box;

    public ComboBoxUpdate() {
        // Init
        JPanel panel = new JPanel();
        box = new JComboBox();
        box.addItem("from start");

        box.addPopupMenuListener(this);

        panel.add(box);
        this.add(panel);
        this.pack();
        this.setVisible(true);
    }

    @Override
    public void popupMenuWillBecomeVisible(PopupMenuEvent e) {
        if (box.getItemCount() == 1) {
            box.removeAllItems();
            box.addItem("item 1");
            box.addItem("item 2");
            box.addItem("item 3");
        }
    }

    @Override
    public void popupMenuWillBecomeInvisible(PopupMenuEvent e) {
    }

    @Override
    public void popupMenuCanceled(PopupMenuEvent e) {
    }
}

This makes my box only flash-and-close on first click. How it works: The list displays "Choose car" from start. When clicked only cars should show up. — Grains, May 10 '13 at 08:52

score 1 · Answer 2 · edited May 23 '17 at 12:13

1

I have a JComboBox with only one value in the start and have one MouseListener connected to it. When I click on the JComboBox I fill it with some new values

Item(s) to JComboBox on runtime could be add/remove/modify into XxxComboBoxModel only
use DefaultComboBoxModel in the case that you'll change all Items
use MutableComboBoxModel for add/remove/modify Item(s) on runtime

edited May 23 '17 at 12:13

Community

1
1

answered May 10 '13 at 08:56

mKorbel

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Tried this but still same result: `code`@Override public void mousePressed(MouseEvent e) { if(box.getItemCount() == 1){ String[] newData = {"item1","item2","item3"}; DefaultComboBoxModel model = new DefaultComboBoxModel( newData ); box.setModel( model ); } }`code` – Grains May 10 '13 at 09:04

score 0 · Answer 3 · answered May 10 '13 at 08:37

Try mousePressed() or mouseReleased() events instead of mouseClicked() event. Also you have to repaint() to make the changes visible.

       @Override
        public void mousePressed(MouseEvent e) {
            System.out.println("Pressed");
             if(box.getItemCount() == 1){
                 box.removeAllItems();
                 box.addItem("item 1");
                 box.addItem("item 2");
                 box.addItem("item 3");
                 repaint();
             }
        }

Moved to mousePressed and added repaint() but still same result. — Grains, May 10 '13 at 08:49

Update JComboBox popupMenu

3 Answers3