Set pressed icon for JCheckBox in Java

import javax.swing.Icon;
import javax.swing.ImageIcon;
import javax.swing.JCheckBox;
import javax.swing.JFrame;
public class Main{
  public static void main(String[] argv){
    JFrame frame = new JFrame("JCheckBox Test");
//from w ww. j av  a  2  s . co  m
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    JCheckBox ac = new JCheckBox("A/C");

    Icon i = new ImageIcon("a.gif");
    ac.setPressedIcon(i);
    
    frame.add(ac);
    frame.pack();
    frame.setVisible(true);
  }
}