Java2, Micro Edition (J2ME) is a technology defined by many specifications. These specifications help J2ME address the diverse needs of this wide spectrum of consumer products. This guide describes the architecture of J2ME and demonstrates the various specifications for programming Java applications. Through the use of a tutorial application and various programming examples, the common elements of most applications, namely user interface, event handling, data storage, networking, and input/output are examined. Also covered are design considerations when building software for resource-constrained devices as well as J2ME competition and associated technologies in these devices.