TEMPLE OF KNOWLEDGE: J2ME in a Nutshell

Ebook Summary:

The first nine chapters of this book describe the J2ME platform, the command-line tools that

are provided with Sun's J2ME reference implementations, and some of the visual

development environments that you can use when writing J2ME applications:

Chapter 1:-This chapter introduces the J2ME platform and the concepts of configuration and

profile, and it compares J2ME to a number of other Java platforms for small devices.
Chapter 2:-This chapter covers the Connected Limited Device Configuration (CLDC), which is

the basic building block for the J2ME profiles for wireless devices and PDAs. It

begins by outlining the differences between CLDC and the core libraries of the J2SE

platform. Then it takes a close look at KVM, the small-footprint virtual machine that
is used in Sun's reference implementation of CLDC
Chapter 3:-This chapter introduces MIDlets, the wireless Java equivalent of applets. MIDlets are part of the Mobile Information Device Profile (MIDP), which is the subject of this

and the following three chapters. This chapter looks at the lifecycle of a MIDlet

and illustrates it with a simple example. It concludes with a discussion of the facilities

that a typical mobile device would provide to allow the user to download, install,

manage, and remove MIDlets.
Chapter 4:-The devices that MIDlets run on range from cell phones with a small two-color

display and room for only a few lines of text to PDAs with larger, multicolor screens.

In order to isolate MIDlets from the specifics of the devices on which they are

running, MIDP includes a high-level API that provides simple input and output

controls and the ability to combine these controls to create form-like screens. This

chapter takes a detailed look at the high-level API and provides sample MIDlets that
can be run on cell phones or PDAs
Chapter 5:-This chapter looks at an alternative user interface API that provides lower-level access to a mobile device's screen and input devices. This chapter looks at the details of this

API and shows how to avoid writing code that may not be portable between devices

with different user interface capabilities.
Chapter 6:-Networking is a key feature of a mobile device. The first part of this chapter looks at

the Generic Connection Framework (GCF), which provides the basis for access to

various networking APIs, including optional protocols (such as sockets and

datagrams) and HTTP, which all MIDP implementations are required to support. A

simple example that involves fetching information from a web site is used to illustrate

the use of HTTP on a mobile device and shows how to avoid problems that arise when

working in an environment with limited memory. The second part of this chapter

looks at the facilities available for storing information on a mobile device and

illustrates them by extending the HTTP example to include persistence of information

retrieved from the web site.
Chapter 7:-This chapter looks at the Connected Device Configuration (CDC) and its profiles,

which are designed for use on devices that have more than 2 MB of memory to devote

to the Java platform. It begins by looking at Sun's reference implementation of CDC

and the CVM, the virtual machine for CDC devices, then briefly covers the content of

the CDC-based profiles that are currently defined.
Chapter 8:-This chapter contains reference material for the command-line tools that are provided
with the CLDC and CDC reference implementations and the MIDP for the PalmOS product.
Chapter 9:-This chapter covers the J2ME wireless toolkit, a development environment provided

by Sun that allows you to create and test MIDlets using a cell-phone emulator that can

be customized to resemble a number of different cell phones and PalmOS-based

handhelds. It also looks at how to use the wireless toolkit in conjunction with Sun's

Forte for Java IDE to create a complete development environment, and it investigates

a number of alternative third-party products that provide similar functionality.

These first nine chapters provide a tutorial introduction to J2ME, with particular emphasis on

wireless devices, which are currently the most popular application of J2ME technology.
Chapter 10:- The core of this book, however, is the API quick reference, through Class, Method,
and Field Index, which is a succinct but detailed API reference formatted for optimum ease
of use. Please be sure to read "How To Use This Quick Reference," which appears at the
beginning of the reference section; it explains how to get the most out of this section.