Objectives In this chapter, we discuss the key characteristics of Java and examine
the architecture and execution model of Java. We compare the architecture
and execution model of Java to the approaches taken by other programming
languages. We also discuss the use of Java in web pages. Two very simple
programs, an app and an applet, will be used to illustrate the basic structure
of Java programs and the use of the Java development tools and environment.
Contents 2.1 The Architecture of Java
2.2 Simple Programs
2.2.1 A Simple App
2.2.2 A Simple Applet
Description As the internet is reaching almost everywhere on Earth, the
next logical step would be an inter-planetary internet. NASA is planning
to have the first internet host outside our planet Earth on-line early
21st century. Just imagine how exciting it would be to receive a greeting
message from a close neighbor of our planet Earth: Venus. This app displays
a greeting message: Hello from Venus! The message is in plain text and
is sent to the standard output.
This applet displays the greeting message from Venus graphically. It consists
of a text message and an image of the planet Venus. This program illustrates
the structure of Java applets, and various graphics capabilities such as
text display and font usage (size, style, and color).
