Java Platform, Micro Edition or Java ME is a

computing platform A computing platform, digital platform, or software platform is the infrastructure on which software is executed. While the individual components of a computing platform may be obfuscated under layers of abstraction, the ''summation of the requi ...

for development and deployment of portable code for embedded and

mobile device A mobile device or handheld device is a computer small enough to hold and operate in hand. Mobile devices are typically battery-powered and possess a flat-panel display and one or more built-in input devices, such as a touchscreen or keypad. ...

s (micro-controllers, sensors, gateways, mobile phones, personal digital assistants, TV set-top boxes, printers). Java ME was formerly known as Java 2 Platform, Micro Edition or J2ME. The platform uses the

object-oriented Object-oriented programming (OOP) is a programming paradigm based on the concept of '' objects''. Objects can contain data (called fields, attributes or properties) and have actions they can perform (called procedures or methods and impleme ...

Java Java is one of the Greater Sunda Islands in Indonesia. It is bordered by the Indian Ocean to the south and the Java Sea (a part of Pacific Ocean) to the north. With a population of 156.9 million people (including Madura) in mid 2024, proje ...

programming language, and is part of the Java software-platform family. It was designed by

Sun Microsystems Sun Microsystems, Inc., often known as Sun for short, was an American technology company that existed from 1982 to 2010 which developed and sold computers, computer components, software, and information technology services. Sun contributed sig ...

(now

Oracle Corporation Oracle Corporation is an American Multinational corporation, multinational computer technology company headquartered in Austin, Texas. Co-founded in 1977 in Santa Clara, California, by Larry Ellison, who remains executive chairman, Oracle was ...

) and replaced a similar technology, PersonalJava. In 2013, with more than 3 billion Java ME enabled mobile phones in the market, the platform was in continued decline as smartphones have overtaken feature phones.

History

The platform used to be popular in feature phones, such as Nokia's Series 40 models. It was also supported on the Bada operating system and on

Symbian Symbian is a discontinued mobile operating system (OS) and computing platform designed for smartphones. It was originally developed as a proprietary software OS for personal digital assistants in 1998 by the Symbian Ltd. consortium. Symbian OS ...

OS along with native software. Users of

Windows CE Windows CE, later known as Windows Embedded CE and Windows Embedded Compact, is a discontinued operating system developed by Microsoft for mobile and embedded devices. It was part of the Windows Embedded family and served as the software foun ...

Windows Mobile Windows Mobile is a discontinued mobile operating system developed by Microsoft for smartphones and personal digital assistants (PDA). Designed to be the portable equivalent of the Windows desktop OS in the emerging Mobile device, mobile/port ...

Maemo Maemo is a Linux-based software platform originally developed by Nokia, now developed by the Free software movement, community, for smartphones and Internet tablets. The platform comprises both the Maemo operating system and Software development ...

MeeGo MeeGo is a discontinued Linux distribution hosted by the Linux Foundation, using source code from the operating systems Moblin (produced by Intel) and Maemo (produced by Nokia). MeeGo was primarily targeted at mobile devices and information app ...

and Android could download Java ME for their respective environments ("proof-of-concept" for Android). Originally developed under the

Java Community Process The Java Community Process (JCP), established in 1998, is a formal mechanism that enables interested parties to develop standard technical specifications for Java technology. Becoming a member of the JCP requires solid knowledge of the Java program ...

as JSR 68, the different flavors of Java ME have evolved in separate JSRs. Java ME devices implement a ''profile''. The most common of these are the Mobile Information Device Profile aimed at mobile devices such as cell phones, and the Personal Profile aimed at consumer products and embedded devices like

set-top box A set-top box (STB), also known as a cable converter box, cable box, receiver, or simply box, and historically television decoder or a converter, is an information appliance device that generally contains a Tuner (radio)#Television, TV tuner inpu ...

es and PDAs. Profiles are subsets of ''configurations'', of which there are currently two: the

Connected Limited Device Configuration The Connected Limited Device Configuration (CLDC) is a specification of a framework for Java ME applications describing the basic set of libraries and virtual-machine features that must be present in an implementation. The CLDC is combined with on ...

(CLDC) and the Connected Device Configuration (CDC). In 2008, Java ME platforms were restricted to JRE 1.3 features and use that version of the class file format (internally known as version 47.0).

Implementations

Oracle provides a

reference implementation In the software development process, a reference implementation (or, less frequently, sample implementation or model implementation) is a program that implements all requirements from a corresponding specification. The reference implementation ...

of the specification, and some configurations and profiles for MIDP and CDC. Starting with the JavaME 3.0 SDK, a

NetBeans NetBeans is an integrated development environment (IDE) for Java (programming language), Java. NetBeans allows applications to be developed from a set of modular software components called ''modules''. NetBeans runs on Microsoft Windows, Windows, ...

-based IDE supported them in a single IDE. In contrast to the numerous binary implementations of the Java Platform built by Sun for servers and workstations, Sun tended not to provide binaries for the platforms of Java ME targets, and instead relied on third parties to provide their own. The exception was an MIDP 1.0 JRE (JVM) for Palm OS. Sun provides no J2ME JRE for the Microsoft Windows Mobile (Pocket PC) based devices, despite an open-letter campaign to Sun to release a rumored internal implementation of PersonalJava known by the code name "Captain America". Third party implementations are widely used by Windows Mobile vendors. At some point, Sun released a now-abandoned reference implementation under the name

phoneME A phoneme () is any set of similar Phone (phonetics), speech sounds that are perceptually regarded by the speakers of a language as a single basic sound—a smallest possible Phonetics, phonetic unit—that helps distinguish one word fr ...

. Operating systems targeting Java ME have been implemented by DoCoMo in the form of DoJa, and by SavaJe as SavaJe OS. The latter company was purchased by Sun in April 2007 and now forms the basis of Sun's JavaFX Mobile. The open-source Mika VM aims to implement JavaME CDC/FP, but is not certified as such (certified implementations are required to charge royalties, which is impractical for an open-source project). Consequently, devices which use this implementation are not allowed to claim JavaME CDC compatibility. The Linux-based Android operating system uses a proprietary version of Java that is similar in intent, but very different in many ways from Java ME.Mobile application development: Android compared to J2ME
Feb 2013

Emulators

(WTK, for short) — is a proprietary Java ME emulator, originally provided by Sun Microsystems, and later by Oracle. * MicroEmulator (MicroEMU, for short) — is an open-source Java ME emulator. There are other emulators, including emulators provided as part of development kits by phone manufacturers, such as Nokia, Sony-Ericsson, Siemens Mobile, etc.

Connected Limited Device Configuration

The

(CLDC) contains a strict subset of the Java-class libraries, and is the minimum amount needed for a

Java virtual machine A Java virtual machine (JVM) is a virtual machine that enables a computer to run Java programs as well as programs written in other languages that are also compiled to Java bytecode. The JVM is detailed by a specification that formally descr ...

to operate. CLDC is basically used for classifying myriad devices into a fixed configuration. A configuration provides the most basic set of libraries and virtual-machine features that must be present in each implementation of a J2ME environment. When coupled with one or more profiles, the Connected Limited Device Configuration gives developers a solid Java platform for creating applications for consumer and embedded devices. The configuration is designed for devices with 160KB to 512KB total memory, which has a minimum of 160KB of ROM and 32KB of RAM available for the Java platform.

Mobile Information Device Profile

Designed for mobile phones, the Mobile Information Device Profile includes a GUI, and a data storage API, and MIDP 2.0 includes a basic 2D gaming

API An application programming interface (API) is a connection between computers or between computer programs. It is a type of software interface, offering a service to other pieces of software. A document or standard that describes how to build ...

. Applications written for this profile are called MIDlets. ''JSR 271: Mobile Information Device Profile 3'' (Final release on Dec 9, 2009) specified the 3rd generation Mobile Information Device Profile (MIDP3), expanding upon the functionality in all areas as well as improving interoperability across devices. A key design goal of MIDP3 is backward compatibility with MIDP2 content.

Information Module Profile

The Information Module Profile (IMP) is a profile for embedded, "headless" devices such as vending machines, industrial embedded applications, security systems, and similar devices with either simple or no display and with some limited network connectivity. Originally introduced by Siemens Mobile and

Nokia Nokia Corporation is a Finnish multinational corporation, multinational telecommunications industry, telecommunications, technology company, information technology, and consumer electronics corporation, originally established as a pulp mill in 1 ...

as JSR-195, IMP 1.0 is a strict subset of MIDP 1.0 except that it does not include

user interface In the industrial design field of human–computer interaction, a user interface (UI) is the space where interactions between humans and machines occur. The goal of this interaction is to allow effective operation and control of the machine fro ...

APIs — in other words, it does not include support for the Java package javax.microedition.lcdui. JSR-228, also known as IMP-NG, is IMP's next generation that is based on MIDP 2.0, leveraging MIDP 2.0's new security and networking types and APIs, and other APIs such as PushRegistry and platformRequest(), but again it does not include UI APIs, nor the game API.

Connected Device Configuration

The Connected Device Configuration is a subset of Java SE, containing almost all the libraries that are not GUI related. It is richer than CLDC.

Foundation Profile

The Foundation Profile is a Java ME Connected Device Configuration (CDC) profile. This profile is intended to be used by devices requiring a complete implementation of the Java virtual machine up to and including the entire Java Platform, Standard Edition API. Typical implementations will use some subset of that API set depending on the additional profiles supported. This specification was developed under the Java Community Process.

Personal Basis Profile

The Personal Basis Profile extends the Foundation Profile to include lightweight GUI support in the form of an AWT subset. This is the platform that BD-J is built upon.

JSRs (Java Specification Requests)

Foundation

Main extensions

Future

ESR

The ESR consortium is devoted to Standards for embedded Java. Especially cost effective Standards. Typical applications domains are industrial control, machine-to-machine, medical, e-metering, home automation, consumer, human-to-machine-interface, ...

References

;Notes
JSR 232: Mobile Operational Management
an advanced OSGi technology based platform for mobile computing
JSR 291: Dynamic Component Support for Java SE
symmetric programming model for Java SE to Java ME JSR 232

Bibliography

* * *

External links

Sun Developer Network, Java ME

Nokia's Developer Hub Java pages

Nokia S60 Java Runtime blogs

Sony Ericsson Developer World

Motorola Developer Network

J2ME Authoring Tool LMA Users Network

Samsung Mobile Developer's site

Sprint Application Developer's Website

Performance database of Java ME compatible devices

MicroEJ platforms for embedded systems

Book - Mobile Phone Programming using Java ME (J2ME)

Tutorial Master ng, J2ME
{{Mobile operating systems Computing platforms Platform, Micro Edition Platform, Micro Edition