Question

I am attempting to write a pretty short class that “ties” a JPanel to a JComboBox. I think I have the logic down, but nothing happens when I select something new using the JComboBox… Here is (more or less) my code:

private DisplayPanel currentDisplay; //a displaypanel is simply an extended JPanel with an id field, and an overriden .equals() method
private JComboBox selector;
private List<DisplayPanel> displays;

public SelectionPanel(DisplayPanel panel){
    displays = new ArrayList<DisplayPanel>();
    selector = new JComboBox(new String[]{panel.id});
    currentDisplay = panel;
    selector.addActionListener(this);
    this.add(selector);
    this.add(currentDisplay);
    this.displays.add(panel);
}

public void addNewSelection(DisplayPanel panel){
    displays.add(panel);
    selector.addItem(panel.id);
}


@Override
public void actionPerformed(ActionEvent e) {
    JComboBox source = (JComboBox) e.getSource();
    String id = (String) source.getSelectedItem();
    for(DisplayPanel display: displays)
        if(id.equals(display.id))
                currentDisplay = display;
    this.validate();        
}

I am assuming I need to override the repaint() function somehow, but I am really not sure the best way to do that.

Answer 1

Here is (more or less) my code:

Which doesn’t help us because we don’t know the context of how the code is used. For better help post an SSCCE when asking a question.

currentDisplay = display;

That line of code doesn’t seem correct. All it does is change the value of a variable. It does not add the panel to the GUI. You basic code would be:

panel.remove( theOldPanel );
panel.add( theNewPanel );
panel.revalidate();
panel.repaint();

However, this is exactly what a CardLayout does for you, so the proper solution is to follow aardvarkk’s suggestion.