Transparent JPanel

Question

Hello!
I have a JFrame with a background painted on it and everything works fine so far, but when I create a JPanel in the JFrame the JPanels grey colour is laying on top of the background. So my question is how to make the JPanel transparent. I read about overriding the paintComponent method, but it didn't work, I'm probably doing something wrong.
This is what I did:
class Transparency extends JPanel {
     public Transparency() {}
     @Override
     public void paintComponent(Graphics g) {
          super.paintComponent(g);
contentPanel = new JPanel();
          contentPanel.setPreferredSize(new Dimension(mainFrame.getWidth(), 200));
          contentPanel.setLayout(new BoxLayout(contentPanel, BoxLayout.Y_AXIS));
          contentPanel.add(new Transparency());
          mainPanel.add(contentPanel);I would really appreciate some help!

Answer 1

Newly created JPanel's have their opacity set to true. This means "I guarantee that I will paint all the pixels within my bounds." For many components this amounts to simply filling in the entire bounds of the component with the background color as the first thing they paint. So by setting the opacity to false the JPanel in question will no longer be a gray blob and will allow any components beneath it to show through.
JPanel#setOpacity(false); The panel in question doesn't even need to be a custom subclass (read: delete that Transparency JPanel subclass).