J2ME in a Nutshell

Chapter 2. The Connected Limited Device Configuration

The Connected Limited Device Configuration (CLDC) is the basic building block on which the J2ME profiles for small devices, such as cell phones, pagers, and low-end PDAs, are built. These devices are characterized by their limited memory resources and processing power, which make it impossible for them to host a fully featured Java platform. CLDC specifies a minimal set of Java packages and classes and a reduced functionality Java virtual machine that can be implemented within the resource constraints imposed by such small devices.

The first part of this chapter describes the features that a Java virtual machine capable of supporting CLDC must provide, and it explains how such a VM differs from the standard one required by J2SE. As part of this discussion, we’ll make use of Sun’s reference implementation of the CLDC specification and the Kilobyte Virtual Machine, or KVM, around which it is based. The second part of the chapter covers the Java packages and classes that a CLDC implementation must provide, which are a small subset of the core packages found in J2SE. The chapter concludes with a discussion of the debugging facilities provided by the KVM and a couple of advanced features -- using native code and preloading Java classes -- that will be of interest to readers who want to work with the KVM at the source code level.

The CLDC Java Virtual Machine

The hardware and software limitations imposed by the devices at which CLDC ...