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

/**
   This program demonstrates how to install an action listener 
   using a function expression.
*/
public class ButtonViewer
{  
   private static final int FRAME_WIDTH = 100;
   private static final int FRAME_HEIGHT = 60;

   public static void main(String[] args)
   {  
      JFrame frame = new JFrame();
      JButton button = new JButton("Click me!");
      frame.add(button);
     
      button.addActionListener(
         (ActionEvent event) -> System.out.println("I was clicked."));
      frame.setSize(FRAME_WIDTH, FRAME_HEIGHT);
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.setVisible(true);
   }
}