Java is a programming language A programming language is an artificial language designed to express computations that can be performed by a machine, particularly a computer. Programming languages can be used to create programs that control the behavior of a machine, to express algorithms precisely, or as a mode of human communication originally developed by James Gosling James A. Gosling, O.C., Ph.D. is a software developer, best known as the father of the Java programming language at Sun Microsystems Sun Microsystems, Inc. is a wholly owned subsidiary of Oracle Corporation, selling computers, computer components, computer software, and information technology services. Sun was founded on February 24, 1982. The company was headquartered in Santa Clara, California , on the former west campus of the Agnews Developmental Center (which is now a subsidiary of Oracle Corporation Oracle Corporation is a multinational computer technology corporation that specializes in developing and marketing enterprise software products — particularly database management systems. Headquartered in Redwood City, California, United States, Oracle employs more than 115,000 people worldwide as of 2009[update]. It has enlarged its share of) and released in 1995 as a core component of Sun Microsystems' Java platform Java refers to a number of proprietary computer software products and specifications from Sun Microsystems, a subsidiary of Oracle Corporation, that together provide a system for developing application software and deploying it in a cross-platform environment. Java is used in a wide variety of computing platforms from embedded devices and mobile. The language derives much of its syntax In computer science, the syntax of a programming language is the set of rules that define the combinations of symbols that are considered to be correctly structured programs in that language. The syntax of a language defines its surface form. Text-based programming languages are based on sequences of characters, while visual programming languages from C C is a general-purpose computer programming language developed in 1972 by Dennis Ritchie at the Bell Telephone Laboratories for use with the Unix operating system and C++ but has a simpler object model and fewer low-level In computer science, a low-level programming language is a language that provides little or no abstraction from a computer's instruction set architecture. The word "low" refers to the small or nonexistent amount of abstraction between the language and machine language; because of this, low-level languages are sometimes described as being facilities. Java applications are typically compiled A compiler is a computer program that transforms source code written in a programming language (the source language) into another computer language (the target language, often having a binary form known as object code). The most common reason for wanting to transform source code is to create an executable program to bytecode Java bytecode is the form of instructions that the Java virtual machine executes. Each bytecode opcode is one byte in length, although some require parameters, resulting in some multi-byte instructions. Not all of the possible 256 opcodes are used. In fact, Sun Microsystems, the original creators of the Java programming language, the Java virtual (class file In the Java programming language, source files are compiled into (virtual) machine-readable class files which have a .class extension. Since Java is a platform-independent language, source code is compiled into an output file known as bytecode, which it stores in a .class file. If a source file has more than one class, each class is compiled into) that can run on any Java Virtual Machine A Java Virtual Machine enables a set of computer software programs and data structures to use a virtual machine model for the execution of other computer programs and scripts. The model used by a JVM accepts a form of computer intermediate language commonly referred to as Java bytecode. This language conceptually represents the instruction set of (JVM) regardless of computer architecture In computer science and computer engineering, computer architecture or digital computer organization is the conceptual design and fundamental operational structure of a computer system. It is a blueprint and functional description of requirements and design implementations for the various parts of a computer, focusing largely on the way by which. Java is general-purpose, concurrent, class-based, and object-oriented, and is specifically designed to have as few implementation dependencies as possible. It is intended to let application developers "write once, run anywhere". Java is considered by many as one of the most influential programming languages of the 20th century, and is widely used from application software to web applications.[9][10]
The original and reference implementation In the software development process, a reference implementation is the standard from which all other implementations, with their attendant customizations, are measured, and to which all improvements are added. An improving reference implementation in turn reflects its unchanging specification, or else an attempt at an implementation may prove that Java compilers A compiler is a computer program that transforms source code written in a programming language (the source language) into another computer language (the target language, often having a binary form known as object code). The most common reason for wanting to transform source code is to create an executable program, virtual machines, and class libraries In computer science, a library is a collection of subroutines or classes used to develop software were developed by Sun from 1995. As of May 2007, in compliance with the specifications of the Java Community Process The Java Community Process or JCP, established in 1998, is a formalized process that allows interested parties to get involved in the definition of future versions and features of the Java platform, Sun relicensed most of their Java technologies under the GNU General Public License The GNU General Public License is the most widely used free software license, originally written by Richard Stallman for the GNU project. Others have also developed alternative implementations of these Sun technologies, such as the GNU Compiler for Java The GNU Compiler for Java is a free software compiler for the Java programming language and a part of the GNU Compiler Collection and GNU Classpath GNU Classpath is a project aiming to create a free software implementation of the standard class library for the Java programming language. Despite the massive size of the library to be created, the majority of the task is already done, including Swing, CORBA, and other major parts. The Classpath developers have implemented almost all of the.
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History
See also: Java (software platform)#History Java refers to a number of proprietary computer software products and specifications from Sun Microsystems, a subsidiary of Oracle Corporation, that together provide a system for developing application software and deploying it in a cross-platform environment. Java is used in a wide variety of computing platforms from embedded devices and mobile and Java version history The Java language has undergone several changes since JDK 1.0 as well as numerous additions of classes and packages to the standard library. Since J2SE 1.4, the evolution of the Java language has been governed by the Java Community Process , which uses Java Specification Requests (JSRs) to propose and specify additions and changes to the JavaJames Gosling James A. Gosling, O.C., Ph.D. is a software developer, best known as the father of the Java programming language initiated the Java language project in June 1991 for use in one of his many set-top box A set-top box or set-top unit (STU) is a device that connects to a television and an external source of signal, turning the signal into content which is then displayed on the television screen or other display device projects.[11] Java was originally designed for interactive television, but it was too advanced.[12] The language, initially called Oak after an oak tree An Oak is a tree or shrub in the genus Quercus , of which about 600 species exist on earth. "Oak" may also appear in the names of species in related genera, notably Lithocarpus. The genus is native to the northern hemisphere, and includes deciduous and evergreen species extending from cold latitudes to tropical Asia and the Americas that stood outside Gosling's office, also went by the name Green and ended up later renamed as Java, from a list of random words.[13] Gosling aimed to implement a virtual machine A virtual machine is a software implementation of a machine (i.e. a computer) that executes programs like a physical machine and a language that had a familiar C C is a general-purpose computer programming language developed in 1972 by Dennis Ritchie at the Bell Telephone Laboratories for use with the Unix operating system/C++ style of notation.[14]
Sun Microsystems released the first public implementation as Java 1.0 in 1995. It promised "Write Once, Run Anywhere" (WORA), providing no-cost run-times on popular platforms In computing, a platform describes some sort of hardware architecture and software framework , that allows software to run. Typical platforms include a computer's architecture, operating system, programming languages and related user interface (runtime libraries or graphical user interface). Fairly secure and featuring configurable security, it allowed network- and file-access restrictions. Major web browsers soon incorporated the ability to run Java applets In computing, an applet is any small application that performs one specific task; sometimes running within the context of a larger program, perhaps as a plugin. However, the term typically also refers to programs written in the Java programming language which are included in an HTML page. The word Applet was first used in 1993 by the application within web pages, and Java quickly became popular. With the advent of Java 2 (released initially as J2SE 1.2 in December 1998), new versions had multiple configurations built for different types of platforms. For example, J2EE targeted enterprise applications and the greatly stripped-down version J2ME for mobile applications (Mobile Java). J2SE designated the Standard Edition. In 2006, for marketing purposes, Sun renamed new J2 versions as Java EE Java Platform, Enterprise Edition or Java EE is a widely used platform for server programming in the Java programming language. The Java platform differs from the Java Standard Edition Platform (Java SE) in that it adds libraries which provide functionality to deploy fault-tolerant, distributed, multi-tier Java software, based largely on modular, Java ME Java Platform, Micro Edition, or Java ME, is a Java platform designed for mobile devices and embedded systems. Target devices range from industrial controls to mobile phones and set-top boxes. Java ME was formerly known as Java 2 Platform, Micro Edition (J2ME), and Java SE, respectively.
In 1997, Sun Microsystems approached the ISO/IEC JTC1 ISO/IEC JTC 1 is Joint Technical Committee 1 of the International Organization for Standardization and the International Electrotechnical Commission (IEC). It deals with all matters of information technology standards body and later the Ecma International Ecma International is an international, private (membership-based) non-profit standards organization for information and communication systems. It acquired its name in 1994, when the European Computer Manufacturers Association (ECMA) changed its name to reflect the organization's international reach. As a consequence, the name is no longer to formalize Java, but it soon withdrew from the process.[15] Java remains a de facto De facto is a Latin expression that means "by [the] fact". In law, it is meant to mean "in practice but not necessarily ordained by law" or "in practice or actuality, but without being officially established". It is commonly used in contrast to de jure when referring to matters of law, governance, or technique (such standard, controlled through the Java Community Process The Java Community Process or JCP, established in 1998, is a formalized process that allows interested parties to get involved in the definition of future versions and features of the Java platform.[16] At one time, Sun made most of its Java implementations available without charge, despite their proprietary software The term proprietary software is often used to mean computer software which is neither free nor open source . Terminology for forms of software licensing is not fully standardized and can be controversial. A literal meaning of "proprietary" in relation to software is that it has a copyright owner who can exercise control over what users status. Sun generated revenue from Java through the selling of licenses for specialized products such as the Java Enterprise System. Sun distinguishes between its Software Development Kit (SDK) A software development kit is typically a set of development tools that allows for the creation of applications for a certain software package, software framework, hardware platform, computer system, video game console, operating system, or similar platform and Runtime Environment (JRE) HotSpot is the primary Java Virtual Machine for desktops and servers produced by Oracle Corporation. It features techniques such as just-in-time compilation and adaptive optimization designed to improve performance (a subset of the SDK); the primary distinction involves the JRE's lack of the compiler, utility programs, and header files.
On November 13, 2006, Sun released much of Java as open source software Open-source software is computer software that is available in source code form for which the source code and certain other rights normally reserved for copyright holders are provided under a software license that permits users to study, change, and improve the software. Open source licenses often meet the requirements of the Open Source under the terms of the GNU General Public License The GNU General Public License is the most widely used free software license, originally written by Richard Stallman for the GNU project (GPL). On May 8, 2007, Sun finished the process, making all of Java's core code available under free software Free software, software libre or libre software is software that can be used, studied, and modified without restriction, and which can be copied and redistributed in modified or unmodified form either without restriction, or with minimal restrictions only to ensure that further recipients can also do these things and that manufacturers of consumer-/open-source distribution terms, aside from a small portion of code to which Sun did not hold the copyright.[17]
Sun's vice-president Rich Green has said that Sun's ideal role with regards to Java is as an "evangelist."[18]
Principles
There were five primary goals in the creation of the Java language:[19]
- It should be "simple, object oriented, and familiar".
- It should be "robust and secure".
- It should be "architecture neutral and portable".
- It should execute with "high performance".
- It should be "interpreted, threaded, and dynamic".
Practices
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