What is Java technology?

The Java application development platform consists of two parts: a programming language, and an execution environment. It is primarily used to create downloadable applications.

The current version of Java is Java 2, and this is divided into 3 editions: Java 2 Enterprise Edition (found on high-end business machines), Java 2 Standard Edition (found on desktop computers), and Java 2 Micro Edition or J2ME, which works with smaller handheld devices such as mobile phones and PDAs. The reasoning behind all the different editions is to avoid the problems of developing and running apps using a one-size-fits-all configuration -- obviously a small mobile phone can’t crunch the same amount of information as a larger computer.

Looking closer at J2ME

The J2ME platform is not a single specification for a piece of software. Instead it is a collection of technologies and specifications designed for different parts of the small device market. First, there is a configuration, and on top of that there is a profile that defines the functionality of specific devices.

The core of the J2ME platform is formed by two different configurations, Connected Device Configuration (CDC) and Connected Limited Device Configuration (CLDC). A configuration defines central Java technology libraries and virtual machine capabilities. CLDC is targeted at portable devices such as mainstream mobile phones, whereas CDC is targeted at more advanced mobile devices, such as Nokia Communicators.

Creating apps with your phone in mind

On top of the configurations are the profiles that define the key functionality and application programming interfaces (APIs) in a specific device category. The Mobile Information Device Profile (MIDP), which is found on many Nokia models, is a profile for devices using CLDC. It allows developers to make use of parts of the Nokia user interface and hardware such as lights, sound, and vibration.

Want more? Read up on Java technology from the people who created it: Sun Microsystems