How to set a transparent background of JPanel?

Question

Can JPanels background be set to transparent?

My frame is has two JPanels:

• Image Panel and

Answer 1

 public void paintComponent (Graphics g)
    { 
((Graphics2D) g).setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER,0.0f)); // draw transparent background
     super.paintComponent(g);
    ((Graphics2D) g).setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER,1.0f)); // turn on opacity
    g.setColor(Color.RED);
    g.fillRect(20, 20, 500, 300);
     } 

I have tried to do it this way, but it is very flickery