import java.awt.*;
import java.awt.event.*;

/**
 * Greet the user.
 *
 * The class serves as the listener for its own frame,
 * providing a windowClosing method.  It also serves as
 * the listener for its buttons, providing an appropriate
 * actionPerformed method.
 *
 * @author Samuel A. Rebelsky
 * @version 1.0 of February 1999
 */
public class GreetGUI 
  extends WindowAdapter 
  implements ActionListener 
{
  // +--------+--------------------------------------------------
  // | Fields |
  // +--------+

  /** The frame used for interaction. */
  protected Frame gui;
  /** The field in which the user enters a name. */
  protected TextField userName;
  /** The button the user presses. */
  protected Button greet;
  /** The area used for output. */
  protected Label out;

  // +--------------+--------------------------------------------
  // | Constructors |
  // +--------------+

  /** Set up the frame for interaction. */
  protected GreetGUI() {
    // Create the frame (the window).
    gui = new Frame("Greetings");
    gui.setLayout(new FlowLayout());
    gui.addWindowListener(this);
    // Create the entry field.  Initialized to have a number of
    // spaces so that there is room for the user to enter a name.
    userName = new TextField("          ");
    // Create the button.
    greet = new Button("Hi!");
    greet.addActionListener(this);
    // Create the output field.  Right now, we'll use it for
    // instructions.
    out = new Label("Enter your name and press the button.");
    // Add the components to the interface.
    gui.add(userName);
    gui.add(greet);
    gui.add(out);
    gui.pack();
    // And we're ready to go.
    gui.show();
  } // GreetGUI()

  // +----------------+------------------------------------------
  // | Event Handlers |
  // +----------------+

  /** React to a click on the button. */
  public void actionPerformed(ActionEvent evt) {
    // Update the output
    out.setText("Hi there " + userName.getText() + 
                ", welcome to this program.");
  } // actionPerformed(ActionEvent)

  /** React to the closing of the window. */
  public void windowClosing(WindowEvent event) {
    gui.dispose();
    System.exit(0);
  } // windowClosing()

  // +------+----------------------------------------------------
  // | Main |
  // +------+

  /* Start the ball rolling by creating an object. */
  public static void main(String[] args) {
    new GreetGUI();
  } // main(String[])
} // class GreetGUI