Java SE (Java Platform, Standard Edition)

I am adding a JPanel to a JLayeredPane, but JPanel's paintComponent(); is never invoked:

public class Kj02669 extends JLayeredPane { // change to extend JPanel, then its ok.
  Kj02669() {
    setPreferredSize(new Dimension(350, 400));
    add(new Piece());
    // add(new Piece(), 1); // <-- also fails
  }

      class Piece extends JPanel {
        public Piece() {
          setPreferredSize(new Dimension(200, 200));
        }
        @Override
        public void paintComponent(Graphics g) { // <-- never invoked
          super.paintComponent(g);
          System.out.println("why doesn't this print?");
        }
      }
}

If I have Kj02669 extend JPanel, (not JLayeredPane), then it works. Each JPanel added has their paintComponent(); method automatically invoked. What methods am I forgetting to invoke on JLayeredPane to have an added JPanel's paintComponent() method automatically invoked?

I see a way to get the behaviour I want by overriding paintComponent() in JLayeredPane and from there directly invoke the paint() methods of each added JPanel. But I should not need to do this?
thanks.