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This article will explain in detail how to parse the two types of J2ME configuration. The content of the article is of high quality, so the editor will share it with you for reference. I hope you will have some understanding of the relevant knowledge after reading this article.

Let's focus on the issue of J2ME configuration. The J2ME configuration provided by Sun is suitable for different levels of market needs-CLDC is suitable for small devices, while CDC is suitable for large devices. The two configuration types of J2ME are CLDC and CDC.

J2ME configuration

What is the 1.J2ME configuration?

As  learned earlier, the configuration defines the basic runtime environment as a set of core classes and a specific JVM running on a particular type of device. You can also learn that the two configuration types of J2ME are CLDC and CDC.

The J2ME configuration provided by  Sun is tailored to different levels of market demand-CLDC is suitable for small devices, while CDC is suitable for large devices. The J2ME environment can be dynamically configured to provide the environment needed to run the application, regardless of whether the device is provided with all the Java technical libraries needed to run the application. The core platform receives application code and libraries. The server software running on the network performs the configuration work.

 in the next few pages, you will learn more about CLDC and CDC and the summary tables associated with them.

two。 Connection limit device J2ME configuration (CLDC)

 CLDC is created by JavaCommunityProcess. As defined by SunMicrosystems's Web site, its standard is: "lightweight, smallest coverage area of Java building blocks, suitable for small, resource-constrained devices."

The  J2MECLDC configuration is prepared for a virtual machine and a set of core libraries that will be used in an industry-defined profile. As mentioned in Chapter 2, a summary table defines applications for specific devices by providing domain-specific classes at the top of the basic J2ME configuration. The K virtual machine (KVM), the reference execution of the virtual machine's CLDC, and its KJava profile run on top of the CLDC.

 CLDC briefly describes a basic set of libraries and Java virtual machine characteristics required for each J2ME execution on a highly restricted device. CLDC is mainly aimed at devices with slow network connections, limited energy (often battery powered), stable memory greater than or equal to 128KB, and unstable memory greater than or equal to 32KB. Unstable memory is not persistent and is not write-protected, which means that if the device is turned off, all the contents of the memory will be lost. The content in stable memory is persistent and write-protected. CLDC devices use stable memory to store runtime libraries and KVM, or to store another virtual machine created for a particular device. Unstable memory is used to allocate runtime memory.

3.CLDC requirements

 CLDC defines the following requirements:

◆ 's full Java language support (except floating-point support, finalization, and error handling)

Full JVM support for ◆

Security of ◆ CLDC

Limited internationalization support of ◆

◆ inheritance classes-all classes that are not targeted at CLDC must be subclasses of the J2SE1.3 class

The classes for CLDC are in a package called javax.microedition and its subpackages

 in addition to javax.microedition software package, CLDCAPI is also composed of a subset of J2SE java.io,java.lang and java.util software packages. We will learn the details in the CLDCAPI chapter and then use CLDCAPI to develop our drawing application.

4. Connecting device J2ME configuration (CDC)

The  connected device structure (CDC) is defined as a simplified version of Java2 Standard Edition (J2SE) with CLDC classes added. Therefore, CDC is based on CLDC, and applications developed for CLDC devices can also run on CDC devices.

 CDC is also developed by JavaCommunityProcess, which provides a standardized, portable, fully functional Java2 virtual mechanism building block for users' electronic and embedded devices, such as smart phones, two-way pagers, PDA, household appliances, sales network terminals and car navigation systems. These devices run 32-bit microprocessors and more memory than 2MB, which are necessary to store C virtual machines and libraries. The K virtual machine supports CLDC, while the C virtual machine (CVM) supports CDC.

On how to parse the two types of J2ME configuration is shared here, I hope the above content can be of some help to you, can learn more knowledge. If you think the article is good, you can share it for more people to see.

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