Creating Transparent JPanel using Java

//A program to make the panels transparent in order to view the background unhindered.

import javax.swing.*;
import java.awt.*;

class PanelTransparensy extends JFrame{
private JPanel pnl1,pnl2,pnl3;

public PanelTransparensy(String title){
super(title);
setLayout(new FlowLayout());
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setSize(800,250);

// Change the Background color and see the difference yourselves.
getContentPane().setBackground(Color.white);
setVisible(true);
components();
}
public void components(){

// Panel which is more opaque
pnl1 = new JPanel();
pnl1.setBackground(new Color(0,0,0,125));
pnl1.setPreferredSize(new Dimension(250,150));
pnl1.setBorder(BorderFactory.createTitledBorder("First Panel"));
add(pnl1);

// Panel which is translucent
pnl2 = new JPanel();
pnl2.setBackground(new Color(0,0,0,72));
pnl2.setPreferredSize(new Dimension(250,150));
pnl2.setBorder(BorderFactory.createTitledBorder("Second Panel"));
add(pnl2);

// Panel which is Transparent
pnl3 = new JPanel();
pnl3.setBackground(new Color(0,0,0,2));
pnl3.setPreferredSize(new Dimension(250,150));
pnl3.setBorder(BorderFactory.createTitledBorder("Third Panel"));
add(pnl3);
}

public static void main (String[] args) {
new PanelTransparensy("Transaprent");
}
}