UIManager in Java Swing not working consistently? / JOptionPane Message Background

Question

I'm trying to set the background color in my custom JOptionPane and no matter what, I cannot get the message part of the option pane to change color.

Attempt #1 was to set the pane background and opaque.

Attempt #2 was to also loop through the pane's components, and set the opaque and/or background attributes if they were JPanel or JLabel.

This did not work for the message part. From what I can see, the JPanel does not even exist as one of the components.

Attempt #3 was to use UIManager, however this is not working consistently.

What I mean is, if you were to run the program 5 times, sometimes no background colors are changed, sometimes they all are changed, and sometimes some of them are changed.

I am running inside an invokeLater thread.

UIManager.put("OptionPane.background",Color.white);
UIManager.put("JOptionPane.background",Color.white);
UIManager.put("Panel.background",Color.white);
UIManager.put("JPanel.background",Color.white);

Any ideas?

Answer 1

You can use following workaround:

    JLabel messageLabel = new JLabel("Background is cyan!") {
        /**
         * {@inheritDoc}
         */
        @Override
        public void addNotify() {
            super.addNotify();
            if (getRootPane() != null) {
                List<Component> children = findAllChildren(getRootPane());
                for (Component comp : children) {
                    if (!(comp instanceof JButton)) {
                        comp.setBackground(Color.CYAN);
                    }
                }
            }
        }

        private List<Component> findAllChildren(Component aComp) {
            List<Component> result = new ArrayList<Component>();
            result.add(aComp);
            if (aComp instanceof Container) {
                Component[] children = ((Container) aComp).getComponents();
                for (Component c : children) {
                    result.addAll(findAllChildren(c));
                }
            }
            return result;
        }
    };
    JOptionPane.showConfirmDialog(null, messageLabel, "Test title", JOptionPane.YES_NO_CANCEL_OPTION);