Swing Event Java Tutorial

An adapter class is a term for a class that implements a listener interface with methods that
have no content
(Ivor Horton's Beginning Java 2, JDK 5 Edition by Ivor Horton Wrox Press 2005)

import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import javax.swing.JFrame;
public class Sketcher {
  JFrame window = new JFrame("Sketcher");
  public Sketcher() {
    window.setBounds(30, 30, 300, 300);
    window.addWindowListener(new WindowHandler());
    window.setVisible(true);
  }
  class WindowHandler extends WindowAdapter {
    public void windowClosing(WindowEvent e) {
      System.out.println("closing");
      window.dispose(); // Release the window resources
      System.exit(0); // End the application
    }
  }
  public static void main(String[] args) {
    new Sketcher();
  }
}