CODEWITHSUNDEEP
javaswingjcombobox
Grains
Grains

Reputation: 950

Update JComboBox popupMenu

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) {}
}

Upvotes: 0

Views: 2108

Answers (3)

Ricardo Cacheira
Ricardo Cacheira

Reputation: 807

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) {
    }
}

Upvotes: 1

mKorbel
mKorbel

Reputation: 109815

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

  1. Item(s) to JComboBox on runtime could be add/remove/modify into XxxComboBoxModel only

  2. use DefaultComboBoxModel in the case that you'll change all Items

  3. use MutableComboBoxModel for add/remove/modify Item(s) on runtime

Upvotes: 1

prasanth
prasanth

Reputation: 3602

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();
             }
        }

Upvotes: 0

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