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

public class FirstWindow extends JFrame {
  public static final int WIDTH = 300;
  public static final int HEIGHT = 200;
  
  public FirstWindow() {
    super();
    setSize(WIDTH, HEIGHT);
    setTitle("First Window Program!");
    setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE);
    JButton endButton = new JButton("Click to end program.");
    ActionListener buttonEar = new ActionListener() {
      public void actionPerformed(ActionEvent e) {
        System.exit(0);
      }
    };
    endButton.addActionListener(buttonEar);
    add(endButton);
  }
  
  public static void main(String[] args) {
    FirstWindow w = new FirstWindow();
    w.setVisible(true);
  }
}