Java JFrame handle window focus event

import java.awt.event.WindowEvent;
import java.awt.event.WindowFocusListener;

import javax.swing.JFrame;

class My implements WindowFocusListener {

   public void windowGainedFocus(WindowEvent e) {
     System.out.println("WindowFocusListener method called: windowGainedFocus.");
   }//  w w w  .ja  v a 2s. co m

   public void windowLostFocus(WindowEvent e) {
      System.out.println("WindowFocusListener method called: windowLostFocus.");
   }
}

public class Main {

   public static void main(String[] args) {
      JFrame window = new JFrame("java2s.com");
      window.setBounds(30, 30, 300, 300);
      window.addWindowFocusListener(new My());
      window.setVisible(true);

   }
}