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#REDIRECT [[Java (software platform)]]
[[Image:Java_Logo.svg|130px|right|Java Sun Logo]]
{{Java platforms}}
The Java Platform is the world's most broadly deployed open source software technology, in use by hundreds of millions of users across the world to create, display, operate and interact with services on the internet. The Java platform runs on devices as small as the SIM card in your phone, up into nearly 1 billion Java enabled phones, it runs on myriad set top boxes, hundreds of millions of desktop PC's, and into a diversity of network devices, from servers and storage systems, to network devices.
Formally, the '''Java Platform''' is the name for a bundle of related programs, or [[platform (computing)|platform]], from [[Sun Microsystems]] which allow for developing and running programs written in the [[Java (programming language)|Java programming language]]. The platform is not specific to any one processor or operating system, but rather, an execution engine (called a [[virtual machine]]) and a set of standard libraries which provide common functionality are implemented for various hardware and operatings systems so that Java programs can run identically on all of them.
The '''Java Platform''' (formerly Java 2 Platform[http://java.sun.com/developer/technicalArticles/javaone2005/naming.html]), includes the Java Platform Standard Edition or [[Java SE]] (formerly J2SE), the Java Platform Enterprise Edition or [[Java EE]] (formerly J2EE), and the Java Platform Micro Edition or [[Java ME]] (formerly J2ME). As of Dec. 2006, the current version of the Java Platform is specified as either 1.6.0 or 6 (both refer to the same version). Version 6 is the product version, while 1.6.0 is the developer version. A good overview of the myriad of technologies that makes up the current Java Platform can be found on the [http://java.sun.com/javase/6/docs/ JDK Documentation Page].
== Java technologies ==
The Java platform consists of several programs, each of which provides a distinct portion of its overall capabilities. There is the Java compiler that converts Java source code into Java bytecode (an intermediate language for the [[Java Virtual Machine]] a.k.a. JVM) and provided as part of the [[Java Development Kit]] (JDK). There is a sophisticated [[Java Runtime Environment]] (JRE) that usually implements the JVM by means of a [[Just-in-time_compilation|just-in-time (JIT) compiler]] that converts intermediate bytecode into native machine code on the fly. There are extensive libraries (pre-compiled into Java bytecode) containing reusable code, as well as numerous ways for Java applications to be deployed, including being embedded in a web page as an applet. Taken together, this entire set of software technologies is referred to as the 'Java Platform'.
== Java Virtual Machine ==
{{main|Java Virtual Machine}}
The heart of the Java Platform is the concept of a common "virtual" processor that executes [[Java bytecode]] programs. This bytecode is the same no matter what hardware or operating system the program is running under. The Java Platform provides a [[Just-in-time_compilation|just-in-time (JIT) compiler]] within the ''Java Virtual Machine'', or JVM, which handles execution of Java. The JIT compiler translates the Java bytecode into native processor instructions at run-time and caches the native code in memory during execution.
The use of bytecode as an intermediate language permits Java programs to run on any platform that has a virtual machine available. The use of a JIT compiler means that Java applications, after a short delay during loading and once they have "warmed up" by being all or mostly JIT-compiled, tend to run about as fast as native programs.
Since JRE version 1.2, Sun's JVM implementation has included a [[just-in-time compilation|just-in-time compiler]] instead of an interpreter.
== Class libraries ==
In most modern operating systems, a large body of reusable code is provided to simplify the programmer's job. This code is typically provided as a set of [[Library (computer science)#Dynamic linking|dynamically loadable libraries]] that applications can call at runtime. Because the Java Platform is not dependent on any specific operating system, applications cannot rely on any of the existing libraries. Instead, the Java Platform provides a comprehensive set of standard class libraries, containing much of the same reusable functions commonly found in modern operating systems.
The Java class libraries serve three purposes within the Java Platform. Like other standard code libraries, they provide the programmer a well-known set of functions to perform common tasks, such as maintaining lists of items or performing complex string parsing. In addition, the class libraries provide an abstract interface to tasks that would normally depend heavily on the hardware and operating system. Tasks such as network access and file access are often heavily dependent on the native capabilities of the platform. The Java java.net and java.io libraries implement the required native code internally, then provide a standard interface for the Java applications to perform those tasks. Finally, some underlying platforms may not support all of the features a Java application expects. In these cases, the class libraries can either emulate those features using whatever is available, or provide a consistent way to check for the presence of a specific feature.
== Languages ==
:''See the category [[:Category:JVM programming languages|JVM programming languages]].''
The word Java, by itself, usually refers to the Java programming language which was designed for use with the Java Platform. Programming languages are typically outside of the scope of the phrase "platform", although the Java programming language is listed as a core part of the Java platform. The language and runtime are therefore commonly considered a single unit.
Nevertheless, third parties have produced a number of [[Compiler|compilers]] or [[Interpreter (computing)|interpreters]] which target the JVM. Some of these are for existing languages, while others are for extensions to the Java language itself. These include:
* [[AspectJ]], Java with aspect oriented-programming
* [[Generic Java]] (GJ), which was incorporated into official Java as of Java SE 5.0
* [[Groovy programming language|Groovy]]
* [[BeanShell]]
* [[Jython]], a [[Python (programming language)|Python]] interpreter that include jythonc, a Python-to-Java bytecode compiler
* [[NetREXX]]
* [[Nice programming language|Nice]]
* [[Pizza programming language|Pizza]]
* [[Scala programming language|Scala]]
* [[JRuby]], a [[Ruby (programming language)|Ruby]] interpreter
* [[Sleep programming language|Sleep]], an interpreter mixing [[Perl]] and [[Objective-C]] features
* [[Rhino (JavaScript engine)|Rhino]], a [[JavaScript]] interpreter
== Similar platforms ==
The success of Java and its [[write once, run anywhere]] concept has led to other similar efforts, notably the [[Microsoft .NET]] platform, appearing since 2002, which incorporates many of the successful aspects of Java. However, .NET's goal of making [[List_of_Microsoft_Windows_versions#Current_versions|36+ versions of Windows operating systems]] alike to a programmer did not include non-Windows operating systems or non-Intel-compatible processors. .NET's goals did, however, include a strong emphasis on cross-language library usability, and it has been somewhat more successful than Java in achieving that (though this is rapidly changing as of 2006).
.NET includes an implementation of Java called [[J Sharp programming language|Visual J#]] (formerly known as [[J plus plus|J++]]) that is '''not''' compatible with the Java specification, and the associated class library mostly dates to the old '''JDK 1.1''' version of the language; for these reasons, it is more a transitional language to switch from Java to the [[Microsoft .NET]] platform, than a first class [[Microsoft .NET]] language.
==See also==
*[[List of Java APIs]]
*[[Java (Sun)]]
*[[Java (programming language)]]
*[[http://www.ilog.com/products/jloox/] JLoox graphics suite] sample graphic PENDING
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{{Sun Microsystems}}
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