Applets

1
Applets

• Yong Choi
• School of Business
• CSU, Bakersfield

2
Whats an Applet?

• Applets- Programs that are called from within
  another application
• You run applets on
• the Internet, an intranet, and an extranet
• a local computer from within another program
  called Applet Viewer
• To view an applet, it should be called from
  within another document written in HTML
• Visit Java API to see the applet package

3
Execution of an Applet

• Applets are popular because users can execute
  them using a Web browser
• Web browser A program that allows you to display
  HTML documents on your computer screen
• Internet Explorer
• Netscape Navigator

4
Understanding Simple Applets

• To write an applet you must also
• Include import statements to ensure that
  necessary classes are available
• Learn to use some Windows components and applet
  methods
• Learn to use the keyword extends

5
Writing an HTML Document to Host an Applet

• Code to run an applet from within an HTML
  document (use the clip library of TextPad)
• Need only two tags ltappletgt lt/appletgt but
  usually, programmers need to place three
  attributes within the ltAppletgt tag
• For example
• ltAPPLET CODE MyApplet.class WIDTH 300
  HEIGHT 200gt
• lt/APPLETgt

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Attributes of an Applet

• Applet tag attributes
• CODE is followed by the name of the compiled
  applet you are calling
• WIDTH is followed by the width of the applet on
  the screen
• HEIGHT is followed by the height of the applet
  on the screen
• The WIDTH and HEIGHT attributes are measured in
  pixels
• Pixels Picture elements, or tiny dots that make
  up the image on your video monitor

7
Refer to the Java API for detail information
8
Using Labels with Simple AWT Applets

• The java.awt package contains commonly used
  Windows components such as
• Labels
• Menus
• Buttons
• Label Built-in class that holds text that you
  can display within an applet

9
Understanding Component and Container

• Component- A class that defines any object that
  you want to display
• Such as GUI component - Frames, panels, buttons,
  labels, and text fields
• Container- A class that is used to define a
  component that can contain other components
• Your browser is a container that contains
  buttons, labels, text fields..

10
Understanding AWT

• Most AWT applets contain 2 import statements
• import java.applet.
• import java.awt.
• java.applet- Contains a class named Applet
• Every applet you create is based on Applet
• java.awt- The Abstract Windows Toolkit, or AWT
• Used to be a package for GUI in Java 1.1

11
Understanding Simple Applets

• Most Swing applets contain 2 import statements
• import javax.swing.
• import java.awt.
• javax.swing- A package that contains classes that
  define GUI components (refer to as Swing
  components)

12
Complete Applet and GUI

• Part 5 Applets and Graphics
• Part 8 Graphical User Interface Programming