Java JButton handle click event

import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.Icon;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JOptionPane;

public class Main extends JFrame {
  private final JButton okButton; // button with just text
  private final JButton fancyJButton; // button with icons

  // Main adds JButtons to JFrame
  public Main() {
    super("Testing Buttons");
    setLayout(new FlowLayout());

    okButton = new JButton("OK"); 
    add(okButton); // add okButton to JFrame

    Icon bug1 = new ImageIcon(getClass().getResource("1.gif"));
    Icon bug2 = new ImageIcon(getClass().getResource("2.gif"));
    fancyJButton = new JButton("Button", bug1); 
    fancyJButton.setRolloverIcon(bug2); // set rollover image
    add(fancyJButton); // add fancyJButton to JFrame

    // create new ButtonHandler for button event handling
    ButtonHandler handler = new ButtonHandler();
    fancyJButton.addActionListener(handler);
    okButton.addActionListener(handler);
  }/*from   w  ww . j a  v a 2  s .c om*/

  // inner class for button event handling
  private class ButtonHandler implements ActionListener {
    // handle button event
    @Override
    public void actionPerformed(ActionEvent event) {
      JOptionPane.showMessageDialog(Main.this, String.format("You pressed: %s", event.getActionCommand()));
    }
  }

  public static void main(String[] args) {
    Main Main = new Main();
    Main.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    Main.setSize(275, 110);
    Main.setVisible(true);
  }
}