Java Platform: Difference between revisions

Revision as of 11:44, 18 June 2005

Revision as of 21:02, 10 July 2005

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The '''Java [[platform (computing)|Platform]]''' is the name for a computing environment from [[Sun Microsystems]] which can run applications developed using athe standard [[java programming language]] and set of development tools. In this case, the platform is not a specific hardware or operating system, but rather an execution engine called a [[virtual machine]], and a set of standard libraries which provide common functionality.

The platform is properly called the '''Java 2 Platform''', and includes both a Standard Edition or [[J2SE]], an [[Enterprise]] Edition or [[J2EE]], and a Micro Edition or [[J2ME]]. The current version of the Java 2 platform is alternatively specified as version 1.5 or version 5 (both refer to the same version). A good overview of the myriad of technologies that makes up the Java 2 Platform can be found on the [http://java.sun.com/j2se/1.5.0/docs/index.html JDK Documentation Page].

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=== Class libraries ===

In most modern operating systems, a large body of reusable code is provided to simplify the programmers 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 dependantdependent on any specific operating system, applications cannot rely of 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 dependantdependent 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 ==

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". However, Sun does not encourage the use of any other languages with the platform, and lists the Java programming language as a core part of the Java 2 platform. The language and runtime are therefore commonly considered a single unit.

Nevertheless, third parties have produced a number of compilers which target the JVM. Some of these are for existing languages, while others are for extensions to the Java language itself. These include: