Applets in the WWW:

  1. What is an applet:

    Applet is compiled Java program that is downloaded from a Web Server and runned on YOUR computer.

  2. Applet can potentially be a huge security problem (like viruses)...

  3. Why use Applet:

  4. How to put an Applet on a web page:

    Applet written in Java Version 1:
        <APPLET
           CODE="RectangleApplet.class"
           WIDTH="400" HEIGHT="300">  
       </APPLET>
    

    Applet written in Java Version 2:
        <EMBED
           TYPE="application/x-java-applet;version=1.2"
           archive="classes111.zip"
           CODE="RectangleApplet.class"
           WIDTH="400" HEIGHT="300">  
       </EMBED>
    

    The result:

    The CODE tag specifies the Java applet program that will be downloaded and run in browser

  5. The source of the applet program is:

    public class RectangleApplet extends Applet { public void paint(Graphics g) { // recover Graphics2D Graphics2D g2 = (Graphics2D)g; *************************** * Actual drawing command: * *************************** // Pick drawing color g2.setColor(Color.red); // construct a rectangle and draw it Rectangle cerealBox = new Rectangle(5, 10, 20, 30); g2.draw(cerealBox); // move rectangle 15 units sideways and 25 units down cerealBox.translate(15, 25); // draw moved rectangle g2.setColor(Color.blue); g2.fill(cerealBox); } }

    Where is main() ??? ...Details on what the applet is doing will be discussed later...