Java Reference
In-Depth Information
Chapter 1. Java 2 Micro Edition Overview
IN THIS CHAPTER
This chapter gives a general overview of the Java 2 Micro Edition (J2ME). Starting from the
Green Project, the origin of this fascinating new technology, this chapter gives a short summary of
the evolutionary process leading to the actual configurations and profiles specified in the Java
Community Process (JCP). Then, it discusses the Software Development Kits available from Sun,
including a short programming example. It also describes the additional building steps necessary
for the Connected Limited Device Configuration (CLDC), Mobile Information Device Profile
(MIDP), and the PDA profile (PDAP). Finally, it gives a brief description of some third-party
products relevant for J2ME application development.
Note
If you are already familiar with the history of Java and the Java 2 Micro Edition
technology, you can skip this section and go directly to the description of the J2ME
configurations and profiles.
Historical Evolution
Looking back, several projects have dealt with Java-related programming languages used on
consumer devices. These projects were mostly feasibility studies and they were never standardized;
but, many of the ideas were incorporated into the J2ME standards. It makes sense to look at the
origins of these components to gain a better understanding of why things are as they are in J2ME.
The Green Project
The Green Project began in December 1990. Some people at Sun decided to try to figure out what
the next step would be in the evolution of computing and how they could be part of it. They came
to the conclusion that the next evolutionary step would be the merger of digitally controlled
consumer devices and computers—the kinds of devices we know as Personal Digital Assistants
(PDAs) today.
The Sun engineers developed a new SPARC-based, wireless handheld PDA called Star7 or *7.
This newly created device was equipped with a 5-inch, 16-bit color LCD with touch-screen input
capabilities. In addition, it was capable of communicating with other *7 devices over a built-in
900MHz wireless network. This small device required the development of an OS that would fit in
only one megabyte of RAM.
The original plan was to develop the Star7 operating system using C++. However, one of the
members of the Green Project, James Gosling, became fed up with C++ and decided to develop a
new programming language. The result of his work was a programming language called Oak,
