Introduction to MIDP on J2ME
Mobile Information Device Profile (MIDP) defines the Java application environment for mobile information devices (MIDs), such as mobile phones and personal digital assistants (PDAs). MIDP is part of the Java™ 2 Platform, Micro Edition (J2ME™). This guide offers advice for MIDP 2.0, which is specified in MIDP 2.0 Specification  from the Mobile Information Device Profile 2.0 (JSR-000118).
An application that runs in the MIDP environment is called a MIDlet. One or more MIDlets packaged together for distribution are called a MIDlet suite.
This book is for two groups of readers: those who are porting MIDP to a new device (MIDP implementors) and those who are creating MIDlet suites (application developers). Porting MIDP implementations to devices and designing MIDlets both have special challenges, which this book's guidelines address.
The guidelines are divided into three categories. The following paragraphs show the typographical conventions used for the guidelines, and explain the guidelines themselves.
Strongly Recommend: Guidelines that, if not followed, could result in an unusable application.
Recommend: Guidelines that lead to an improved Java application in areas such as ease-of-use and portability. Disregarding this advice will not lead to an unusable application.
Consider: Guidelines that could lead to an improved Java application, but that do not necessarily apply to all applications and situations. Your circumstances may lead you to disregard this advice.
The guidelines come from many sources, including usability studies, user-interface design principles, good coding practices, and experience implementing the MIDP specification and MIDlets.
This chapter introduces design considerations for MIDlets in the consumer market. Designing MIDlets differs significantly from designing desktop computer software. Some important differences include product domain, resource limitations, and the need to focus on ease of use.
1.1 Consumer Characteristics
Consumer-application users have different characteristics than users of desktop systems. Consumers are familiar with appliances that typically have simple, predictable UIs, such as phones, microwave ovens, and remote controls, and might feel uncomfortable dealing with anything they consider too “high-tech.” They expect consumer products to be predictable, easy to learn, and easy to use.
While electronic appliances are common today, widespread acceptance of new products is still hard fought. Eight of ten consumer products fail in the marketplace, often because consumers find them too difficult to use.
Application Developers and MIDP Implementors
Recommend: Make new devices and applications as familiar, responsive, easy to learn, and easy to use as possible.