Interfaces, GUIs, and Applets

CS 161 - Java

What Does an Applet Look Like?

Source: examples/SimpleApplet.java



/** A very simple expamle of a Java GUI applet

 **/

 

// AWT components and Event classes used:

 

import java.applet.Applet;

import java.awt.Button;

import java.awt.Frame;

 

import java.awt.event.ActionListener;   // interface

import java.awt.event.ActionEvent;      // events that interface relates to

 

public class SimpleApplet extends Applet implements ActionListener {

 

  // we don't need a frame; the applet itself is a kind of

  // (extends a) GUI component container called a Panel.

  private Button doSomethingButton = null;

 

  /** Constructor: make a frame to hold the GUI components and the

   ** GUI components themselves.

   **/

  public void init() {

    doSomethingButton = new Button("Do Something");

 

    // This object that is being constructed agrees to listen for

    // events the button will generate.

    doSomethingButton.addActionListener(this);

 

    // add the button to the applet

    add(doSomethingButton);

  }

 

  /** run the application

   **/

  public void start() {

    // the browser will make the components visible

  }

 

  public void stop() {

  }

 

  public void destroy() {

  }

 

  public void actionPerformed(ActionEvent e) {

    // Where do you think thhis output will appear?

    System.out.println("You pressed the button");

  }

}

jwd