Zeller's Congruence

/*
 * EventsUsingInnerClass.java
 *
 * Copyright 2013 Ajay Bhatia <ajay@dumb-box>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
 * MA 02110-1301, USA.
 *
 *
 */

import javax.swing.JFrame;
import javax.swing.JButton;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import javax.swing.JOptionPane;

class FrameWithEvents extends JFrame {
    private JButton button;
  
    FrameWithEvents() {
        button = new JButton("Click Me!");
        add(button);
      
        EventHandler eventHandler = new EventHandler();
        button.addActionListener(eventHandler);
    }
  
    private class EventHandler implements ActionListener {
        public void actionPerformed(ActionEvent ae) {
            JOptionPane.showMessageDialog(null, "You actually clicked a button!");  
        }
    }

}

public class EventsUsingInnerClass {
  
    public static void main (String args[]) {
        FrameWithEvents frame = new FrameWithEvents();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setLocationRelativeTo(null);
        frame.pack();
        frame.setVisible(true);
    }
}