The Corresponding Java Class

• Many IDEs, such as Sun One, have an option to create an Applet.  You might want to do that.
• It will create for you a class that extends Applet.

You should make sure that packages:
• java.applet.Applet;
• java.awt.Graphics;
are imported.  If not, enter the import lines yourself.
• This class will also have a method called init(), which is similar to our public static void main(String[] args) method.  init() is the first method called by the browser.
• Food for thought: do we still want a public static void main(String[] args) method?
• You can get the parameter values by passing the name of the parameter (from the PARAM tag) to the method getParameter(String name).
• Note that this method does not have an implicit parameter.  Why not?
• To write text to the browser, make a method.
• public void paint(Graphics g)
• In that method, g.drawString, similar to the way you call System.out.println().
• But, with drawString, you must specify the height and width as ints.
• example: g.drawString("Celcius temperature is: " + celciusTemp, 50, 25);
• How does this work?  You're overriding the method called paint().  When the browser opens, or the browser is refreshed, Java calls the paint method on your object.
• If you do not have one, it simply does what paint does by default - paints a blank screen.
• If you do have one, it will perform whatever you put in the method.  In this case, we tell it to print a String.
• A few more words....
• There are much sexier interfaces that we can use.  We can add buttons, text input fields, scrollbars, and more.  Just about anything you would see in a GUI application.  But that's pretty advanced, so we'll save that discussion for Java II.
• You have been warned... since most browsers use an old version of java - usually 1.0.2 or 1.1, many of the features you are used to in 1.4.1 are not available.


 Example
 

Created by:  Brandan Jones February 15, 2002