How to check if a component exists in Swing?

[Alan Blass]

Hi! How do I check if a component exists in a container and replace it if it exists. I have tried:

    
                        JPanel panel = new JPanel;
                        GroupLayout layout = new GroupLayout(panel);
                        panel.setLayout(layout);
                        JButtton deleteBtn = new JButton("Delete Button");
                        JLabel deleteLabel = new JLabel("Delete Label");
                        panel.addLayoutComponent(deleteBtn);
                        Component component[] = panel.getComponents();
                        for (Component components: component) {
                            if (components.equals(deleteBtn)) {
                                layout.replace(deleteBtn, deleteLabel);
                            }
                        }

Please help. Thanks

[Darryl Burke]

To get better help sooner, post a SSCCE that demonstrates the incorrect behaviour.

[Paul Clapham]

Alan Blass wrote:Hi! How do I check if a component exists in a container and replace it if it exists.

If you have a requirement to know whether a container actually contains a particular component, then you should write your application to keep track of that information. For example, when you add the component to the container, set some boolean flag to true. And when you remove it from the container, set that flag to false.

[Rob Camick]

I would guess the problem is the GroupLayout. You can't just use:

panel.addLayoutComponent(deleteBtn); 

You need to specify a bunch of constraints to control the horizontal and vertical positioning. That is why this layout is only used by IDE's that generate the code.

I would suggest you try using a differnt layout manager.

[Rob Spoor]

When called during runtime, remember to call revalidate() and repaint() on the JPanel. Components do not trigger any updates to be repainted when their hierarchical structure is modified.

[Alan Blass]

Thanks all for your suggestions.

[Darryl Burke]

Rob Prime wrote:When called during runtime, remember to call revalidate() and repaint() on the JPanel. Components do not trigger any updates to be repainted when their hierarchical structure is modified.

I was going to suggest that when I read the OP, but found that GroupLayout#replace takes care of it.