import javax.swing.*;
import java.awt.event.*;

class ButtonListener implements ActionListener {
    @Override
    public void actionPerformed(ActionEvent e) {
        JOptionPane.showMessageDialog(null, "You pushed the button!!");
    }
}

public class EventExample {
    public static void main(String[] args) {
        // create and set up the window.
        JFrame frame = new JFrame("Button Example!");

        // make the program close when the window closes
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        // add a button object
        JButton button = new JButton("Push Me!");
        button.addActionListener(new ButtonListener());
        frame.getContentPane().add(button);

        // display the window.
        frame.pack();
        frame.setVisible(true);
    }    
}