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Java is a set of
computer software Software is a set of computer programs and associated documentation and data. This is in contrast to hardware, from which the system is built and which actually performs the work. At the lowest programming level, executable code consist ...
and specifications developed by
James Gosling James Gosling (born May 19, 1955) is a Canadian computer scientist, best known as the founder and lead designer behind the Java programming language. Gosling was elected a member of the National Academy of Engineering in 2004 for the conception ...
at
Sun Microsystems Sun Microsystems, Inc. (Sun for short) was an American technology company that sold computers, computer components, software, and information technology services and created the Java programming language, the Solaris operating system, ZFS, t ...
, which was later acquired by the
Oracle Corporation Oracle Corporation is an American multinational computer technology corporation headquartered in Austin, Texas. In 2020, Oracle was the third-largest software company in the world by revenue and market capitalization. The company sells da ...
, that provides a system for developing
application software Application may refer to: Mathematics and computing * Application software, computer software designed to help the user to perform specific tasks ** Application layer, an abstraction layer that specifies protocols and interface methods used in a ...
and deploying it in a
cross-platform In computing, cross-platform software (also called multi-platform software, platform-agnostic software, or platform-independent software) is computer software that is designed to work in several computing platforms. Some cross-platform software ...
computing environment. Java is used in a wide variety of
computing platform A computing platform or digital platform is an environment in which a piece of software is executed. It may be the hardware or the operating system (OS), even a web browser and associated application programming interfaces, or other underlying so ...
s from embedded devices and
mobile phone A mobile phone, cellular phone, cell phone, cellphone, handphone, hand phone or pocket phone, sometimes shortened to simply mobile, cell, or just phone, is a portable telephone that can make and receive calls over a radio frequency link whi ...
s to enterprise servers and
supercomputer A supercomputer is a computer with a high level of performance as compared to a general-purpose computer. The performance of a supercomputer is commonly measured in floating-point operations per second ( FLOPS) instead of million instructio ...
s.
Java applet Java applets were small applications written in the Java programming language, or another programming language that compiles to Java bytecode, and delivered to users in the form of Java bytecode. The user launched the Java applet from a ...
s, which are less common than standalone Java applications, were commonly run in secure, sandboxed environments to provide many features of native applications through being embedded in
HTML The HyperText Markup Language or HTML is the standard markup language for documents designed to be displayed in a web browser. It can be assisted by technologies such as Cascading Style Sheets (CSS) and scripting languages such as JavaS ...
pages. Writing in the
Java programming language Java is a high-level, class-based, object-oriented programming language that is designed to have as few implementation dependencies as possible. It is a general-purpose programming language intended to let programmers ''write once, run anywh ...
is the primary way to produce code that will be deployed as
byte code Bytecode (also called portable code or p-code) is a form of instruction set designed for efficient execution by a software interpreter. Unlike human-readable source code, bytecodes are compact numeric codes, constants, and references (norma ...
in 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 describe ...
(JVM); byte code
compiler In computing, a compiler is a computer program that translates computer code written in one programming language (the ''source'' language) into another language (the ''target'' language). The name "compiler" is primarily used for programs tha ...
s are also available for other languages, including
Ada Ada may refer to: Places Africa * Ada Foah, a town in Ghana * Ada (Ghana parliament constituency) * Ada, Osun, a town in Nigeria Asia * Ada, Urmia, a village in West Azerbaijan Province, Iran * Ada, Karaman, a village in Karaman Province, T ...
,
JavaScript JavaScript (), often abbreviated as JS, is a programming language that is one of the core technologies of the World Wide Web, alongside HTML and CSS. As of 2022, 98% of websites use JavaScript on the client side for webpage behavior, of ...
, Python, and
Ruby A ruby is a pinkish red to blood-red colored gemstone, a variety of the mineral corundum ( aluminium oxide). Ruby is one of the most popular traditional jewelry gems and is very durable. Other varieties of gem-quality corundum are called ...
. In addition, several languages have been designed to run natively on the JVM, including
Clojure Clojure (, like ''closure'') is a dynamic and functional dialect of the Lisp programming language on the Java platform. Like other Lisp dialects, Clojure treats code as data and has a Lisp macro system. The current development process is comm ...
, Groovy, and Scala. Java syntax borrows heavily from C and
C++ C++ (pronounced "C plus plus") is a high-level general-purpose programming language created by Danish computer scientist Bjarne Stroustrup as an extension of the C programming language, or "C with Classes". The language has expanded significan ...
, but object-oriented features are modeled after
Smalltalk Smalltalk is an object-oriented, dynamically typed reflective programming language. It was designed and created in part for educational use, specifically for constructionist learning, at the Learning Research Group (LRG) of Xerox PARC by Alan ...
and
Objective-C Objective-C is a general-purpose, object-oriented programming language that adds Smalltalk-style messaging to the C programming language. Originally developed by Brad Cox and Tom Love in the early 1980s, it was selected by NeXT for its NeXT ...
. Java eschews certain low-level constructs such as pointers and has a very simple memory model where objects are allocated on the heap (while some implementations e.g. all currently supported by Oracle, may use
escape analysis In compiler optimization, escape analysis is a method for determining the dynamic scope of pointers where in the program a pointer can be accessed. It is related to pointer analysis and shape analysis. When a variable (or an object) is allocat ...
optimization to allocate on the
stack Stack may refer to: Places * Stack Island, an island game reserve in Bass Strait, south-eastern Australia, in Tasmania’s Hunter Island Group * Blue Stack Mountains, in Co. Donegal, Ireland People * Stack (surname) (including a list of people ...
instead) and all variables of object types are
references Reference is a relationship between objects in which one object designates, or acts as a means by which to connect to or link to, another object. The first object in this relation is said to ''refer to'' the second object. It is called a ''name'' ...
. Memory management is handled through integrated automatic
garbage collection Waste collection is a part of the process of waste management. It is the transfer of solid waste from the point of use and disposal to the point of treatment or landfill. Waste collection also includes the curbside collection of recyclabl ...
performed by the JVM. On November 13, 2006, Sun Microsystems made the bulk of its implementation of Java available under the
GNU General Public License The GNU General Public License (GNU GPL or simply GPL) is a series of widely used free software licenses that guarantee end users the four freedoms to run, study, share, and modify the software. The license was the first copyleft for general ...
(GPL). The latest version is Java 19, released in September 2022, while Java 17, the latest
long-term support Long-term support (LTS) is a product lifecycle management policy in which a stable release of computer software is maintained for a longer period of time than the standard edition. The term is typically reserved for open-source software, where i ...
(LTS), was released in September 2021. As an open source platform, Java has many distributors, including Amazon, IBM, Azul Systems, and AdoptOpenJDK. Distributions include Amazon Corretto, Zulu, AdoptOpenJDK, and Liberica. Regarding Oracle, it distributes Java 8, and also makes available e.g. Java 11, both also currently supported LTS versions. Oracle (and others) "highly recommend that you uninstall older versions of Java" than Java 8, because of serious risks due to unresolved security issues. Since Java 9 (as well as versions 10-16, and 18-19) are no longer supported, Oracle advises its users to "immediately transition" to a supported version. Oracle released the last free-for-commercial-use public update for the
legacy In law, a legacy is something held and transferred to someone as their inheritance, as by will and testament. Personal effects, family property, marriage property or collective property gained by will of real property. Legacy or legacies may refer ...
Java 8 LTS in January 2019, and will continue to support Java 8 with public updates for personal use indefinitely. Oracle extended support for Java 6 ended in December 2018.


Platform

The Java platform is a suite of programs that facilitate developing and running programs written in the
Java Java (; id, Jawa, ; jv, ꦗꦮ; su, ) is one of the Greater Sunda Islands in Indonesia. It is bordered by the Indian Ocean to the south and the Java Sea to the north. With a population of 151.6 million people, Java is the world's mo ...
programming language. A Java platform includes an execution engine (called a
virtual machine In computing, a virtual machine (VM) is the virtualization/ emulation of a computer system. Virtual machines are based on computer architectures and provide functionality of a physical computer. Their implementations may involve specialized h ...
), a compiler and a set of
libraries A library is a collection of Document, materials, books or media that are accessible for use and not just for display purposes. A library provides physical (hard copies) or electronic media, digital access (soft copies) materials, and may be a ...
; there may also be additional servers and alternative libraries that depend on the requirements. Java platforms have been implemented for a wide variety of hardware and operating systems with a view to enable Java programs to run identically on all of them. Different platforms target different classes of device and
application domain An application domain is a mechanism (similar to a process in an operating system) used within the Common Language Infrastructure (CLI) to isolate executed software applications from one another so that they do not affect each other. Each applic ...
s: * Java Card: A technology that allows small Java-based applications (
applet In computing, an applet is any small application that performs one specific task that runs within the scope of a dedicated widget engine or a larger program, often as a plug-in. The term is frequently used to refer to a Java applet, a program ...
s) to be run securely on
smart card A smart card, chip card, or integrated circuit card (ICC or IC card) is a physical electronic authentication device, used to control access to a resource. It is typically a plastic credit card-sized card with an embedded integrated circuit (IC) c ...
s and similar small-memory devices. *
Java ME Java Platform, Micro Edition or Java ME is a computing platform for development and deployment of portable code for embedded and mobile devices (micro-controllers, sensors, gateways, mobile phones, personal digital assistants, TV set-top ...
(Micro Edition): Specifies several different sets of libraries (known as profiles) for devices with limited storage, display, and power capacities. It is often used to develop applications for mobile devices, PDAs, TV set-top boxes, and printers. *
Java SE Java Platform, Standard Edition (Java SE) is a computing platform for development and deployment of portable code for desktop and server environments. Java SE was formerly known as Java 2 Platform, Standard Edition (J2SE). The platform uses Ja ...
(Standard Edition): For general-purpose use on desktop PCs, servers and similar devices. * Jakarta EE (Enterprise Edition): Java SE plus various APIs which are useful for multi-tier client–server
enterprise application Enterprise software, also known as enterprise application software (EAS), is computer software used to satisfy the needs of an organization rather than individual users. Such organizations include businesses, schools, interest-based user groups ...
s. The Java platform consists of several programs, each of which provides a portion of its overall capabilities. For example, the Java compiler, which converts Java source code into Java bytecode (an intermediate language for the JVM), is provided as part of the
Java Development Kit The Java Development Kit (JDK) is a distribution of Java Technology by Oracle Corporation. It implements the Java Language Specification (JLS) and the Java Virtual Machine Specification (JVMS) and provides the Standard Edition (SE) of the Java ...
(JDK). The
Java Runtime Environment Java is a set of computer software and specifications developed by James Gosling at Sun Microsystems, which was later acquired by the Oracle Corporation, that provides a system for developing application software and deploying it in a cros ...
(JRE), complementing the JVM with a just-in-time (JIT) compiler, converts intermediate bytecode into native machine code on the fly. The Java platform also includes an extensive set of libraries. The essential components in the platform are the Java language compiler, the libraries, and the runtime environment in which Java intermediate bytecode executes according to the rules laid out in the virtual machine specification.


Java virtual machine

The heart of the Java platform is the "virtual machine" that executes
Java bytecode In computing, Java bytecode is the bytecode-structured instruction set of the Java virtual machine (JVM), a virtual machine that enables a computer to run programs written in the Java programming language and several other programming langua ...
programs. This bytecode is the same no matter what hardware or operating system the program is running under. However, new versions, such as for Java 10 (and earlier), have made small changes, meaning the bytecode is in general only
forward compatible Forward compatibility or upward compatibility is a design characteristic that allows a system to accept input intended for a later version of itself. The concept can be applied to entire systems, electrical interfaces, telecommunication signals, ...
. There is a JIT (Just In Time) compiler within the ''Java Virtual Machine'', or JVM. 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 compiler In computing, just-in-time (JIT) compilation (also dynamic translation or run-time compilations) is a way of executing computer code that involves compilation during execution of a program (at run time) rather than before execution. This may c ...
instead of an interpreter. Although Java programs are
cross-platform In computing, cross-platform software (also called multi-platform software, platform-agnostic software, or platform-independent software) is computer software that is designed to work in several computing platforms. Some cross-platform software ...
or platform independent, the code of the Java Virtual Machines (JVM) that execute these programs is not. Every supported operating platform has its own JVM.


Class libraries

In most modern
operating system An operating system (OS) is system software that manages computer hardware, software resources, and provides common daemon (computing), services for computer programs. Time-sharing operating systems scheduler (computing), schedule tasks for ef ...
s (OSs), a large body of reusable code is provided to simplify the programmer's job. This code is typically provided as a set of 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 pre-existing OS libraries. Instead, the Java platform provides a comprehensive set of its own standard class libraries containing many of the same reusable functions commonly found in modern operating systems. Most of the system library is also written in Java. For instance, the
Swing Swing or swinging may refer to: Apparatus * Swing (seat), a hanging seat that swings back and forth * Pendulum, an object that swings * Russian swing, a swing-like circus apparatus * Sex swing, a type of harness for sexual intercourse * Swing ri ...
library paints the user interface and handles the events itself, eliminating many subtle differences between how different platforms handle components. The Java class libraries serve three purposes within the Java platform. First, like other standard code libraries, the Java libraries provide the programmer a well-known set of functions to perform common tasks, such as maintaining lists of items or performing complex string parsing. Second, 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 intertwined with the distinctive implementations of each platform. The java.net and java.io libraries implement an abstraction layer in native OS code, then provide a standard interface for the Java applications to perform those tasks. Finally, when some underlying platform does not support all of the features a Java application expects, the class libraries work to gracefully handle the absent components, either by emulation to provide a substitute, or at least by providing a consistent way to check for the presence of a specific feature.


Languages

The word "Java", alone, usually refers to Java programming language that 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 was listed as a core part of the Java platform before Java 7. The language and runtime were therefore commonly considered a single unit. However, an effort was made with the Java 7 specification to more clearly treat the Java language and the Java Virtual Machine as separate entities, so that they are no longer considered a single unit. Third parties have produced many
compiler In computing, a compiler is a computer program that translates computer code written in one programming language (the ''source'' language) into another language (the ''target'' language). The name "compiler" is primarily used for programs tha ...
s or
interpreters Interpreting is a translational activity in which one produces a first and final target-language output on the basis of a one-time exposure to an expression in a source language. The most common two modes of interpreting are simultaneous interp ...
that target the JVM. Some of these are for existing languages, while others are for extensions to the Java language. These include: *
BeanShell BeanShell is a small, free, embeddable Java source interpreter with object scripting language features, written in Java. It runs in the Java Runtime Environment (JRE), dynamically executes standard Java syntax and extends it with common scripting c ...
– a lightweight scripting language for Java (see also
JShell JShell is a Java read-eval-print loop which was first introduced in the JDK 9. It is tracked by JEP 222 ''jshell: The Java Shell (Read-Eval-Print Loop)''. One reason why JShell was proposed for Java 9 is the lack of a standard interactive environ ...
) *
Ceylon Sri Lanka (, ; si, ශ්‍රී ලංකා, Śrī Laṅkā, translit-std=ISO (); ta, இலங்கை, Ilaṅkai, translit-std=ISO ()), formerly known as Ceylon and officially the Democratic Socialist Republic of Sri Lanka, is an ...
– an object-oriented, strongly statically typed programming language with an emphasis on immutability *
Clojure Clojure (, like ''closure'') is a dynamic and functional dialect of the Lisp programming language on the Java platform. Like other Lisp dialects, Clojure treats code as data and has a Lisp macro system. The current development process is comm ...
– a modern,
dynamic Dynamics (from Greek δυναμικός ''dynamikos'' "powerful", from δύναμις ''dynamis'' "power") or dynamic may refer to: Physics and engineering * Dynamics (mechanics) ** Aerodynamics, the study of the motion of air ** Analytical dyn ...
, and
functional Functional may refer to: * Movements in architecture: ** Functionalism (architecture) ** Form follows function * Functional group, combination of atoms within molecules * Medical conditions without currently visible organic basis: ** Functional sy ...
dialect The term dialect (from Latin , , from the Ancient Greek word , 'discourse', from , 'through' and , 'I speak') can refer to either of two distinctly different types of linguistic phenomena: One usage refers to a variety of a language that is ...
of the
Lisp programming language Lisp (historically LISP) is a family of programming languages with a long history and a distinctive, fully parenthesized prefix notation. Originally specified in 1960, Lisp is the second-oldest high-level programming language still in common u ...
on the Java platform *
Gosu Gosu (고수) is a Korean term used to refer to a highly skilled person. In computer gaming the term is usually used to refer to a person who dominated games like ''StarCraft'', ''Counter-Strike'', Tekken, ''Warcraft III'', ''Diablo II'', ''Dot ...
– a general-purpose Java Virtual Machine-based programming language released under the Apache License 2.0 * Groovy – a fully Java interoperable, Java-syntax-compatible, static and dynamic language with features from Python, Ruby, Perl, and Smalltalk * JRuby – a
Ruby A ruby is a pinkish red to blood-red colored gemstone, a variety of the mineral corundum ( aluminium oxide). Ruby is one of the most popular traditional jewelry gems and is very durable. Other varieties of gem-quality corundum are called ...
interpreter *
Jython Jython is an implementation of the Python programming language designed to run on the Java platform. The implementation was formerly known as JPython until 1999. Overview Jython programs can import and use any Java class. Except for some stand ...
– a Python interpreter * Kotlin – an industrial programming language for
JVM 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 describes ...
with full
Java Java (; id, Jawa, ; jv, ꦗꦮ; su, ) is one of the Greater Sunda Islands in Indonesia. It is bordered by the Indian Ocean to the south and the Java Sea to the north. With a population of 151.6 million people, Java is the world's mo ...
interoperability * Rhino – a
JavaScript JavaScript (), often abbreviated as JS, is a programming language that is one of the core technologies of the World Wide Web, alongside HTML and CSS. As of 2022, 98% of websites use JavaScript on the client side for webpage behavior, of ...
interpreter * Scala – a multi-paradigm programming language with non-Java compatible syntax designed as a "better Java"


Similar platforms

The success of Java and its
write once, run anywhere Write once, run anywhere (WORA), or sometimes Write once, run everywhere (WORE), was a 1995 slogan created by Sun Microsystems to illustrate the cross-platform benefits of the Java language. Ideally, this meant that a Java program could be develo ...
concept has led to other similar efforts, notably the
.NET Framework The .NET Framework (pronounced as "''dot net"'') is a proprietary software framework developed by Microsoft that runs primarily on Microsoft Windows. It was the predominant implementation of the Common Language Infrastructure (CLI) until bein ...
, appearing since 2002, which incorporates many of the successful aspects of Java. .NET was built from the ground-up to support multiple programming languages, while the Java platform was initially built to support only the Java language, although many other languages have been made for JVM since. Like Java, .NET languages compile to byte code and are executed by the Common Language Runtime (CLR), which is similar in purpose to the JVM. Like the JVM, the CLR provides memory management through automatic garbage collection, and allows .NET byte code to run on multiple operating systems. .NET included a Java-like language first named J++, then called Visual J# that was incompatible with the Java specification. It was discontinued 2007, and support for it ended in 2015.


Java Development Kit

The ''Java Development Kit'' (''JDK'') is a
Sun The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...
product aimed at Java developers. Since the introduction of Java, it has been by far the most widely used Java
software development kit A software development kit (SDK) is a collection of software development tools in one installable package. They facilitate the creation of applications by having a compiler, debugger and sometimes a software framework. They are normally specific ...
(SDK). It contains a Java compiler, a full copy of the
Java Runtime Environment Java is a set of computer software and specifications developed by James Gosling at Sun Microsystems, which was later acquired by the Oracle Corporation, that provides a system for developing application software and deploying it in a cros ...
(JRE), and many other important development tools.


Java Runtime Environment

The Java Runtime Environment (JRE) released by Oracle is a freely available software distribution containing a stand-alone JVM (HotSpot), the Java
standard library In computer programming, a standard library is the library made available across implementations of a programming language. These libraries are conventionally described in programming language specifications; however, contents of a language's a ...
(
Java Class Library The Java Class Library (JCL) is a set of dynamically loadable libraries that Java Virtual Machine (JVM) languages can call at run time. Because the Java Platform is not dependent on a specific operating system, applications cannot rely on any ...
), a configuration tool, and—until its discontinuation in JDK 9—a browser plug-in. It is the most common Java environment installed on
personal computer A personal computer (PC) is a multi-purpose microcomputer whose size, capabilities, and price make it feasible for individual use. Personal computers are intended to be operated directly by an end user, rather than by a computer expert or te ...
s in the laptop and desktop form factor.
Mobile phone A mobile phone, cellular phone, cell phone, cellphone, handphone, hand phone or pocket phone, sometimes shortened to simply mobile, cell, or just phone, is a portable telephone that can make and receive calls over a radio frequency link whi ...
s including
feature phone A feature phone (also spelled featurephone) is a type or class of mobile phone that retains the form factor of earlier generations of mobile telephones, typically with press-button based inputs and a small non-touch display. They tend to use an ...
s and early
smartphone A smartphone is a portable computer device that combines mobile telephone and computing functions into one unit. They are distinguished from feature phones by their stronger hardware capabilities and extensive mobile operating systems, whi ...
s that ship with a JVM are most likely to include a JVM meant to run applications targeting Micro Edition of the Java platform. Meanwhile, most modern smartphones,
tablet computer A tablet computer, commonly shortened to tablet, is a mobile device, typically with a mobile operating system and touchscreen display processing circuitry, and a rechargeable battery in a single, thin and flat package. Tablets, being com ...
s, and other
handheld PC A handheld personal computer (PC) is a miniature computer typically built around a clamshell form factor and is significantly smaller than any standard laptop computer, but based on the same principles. It is sometimes referred to as a ''palmto ...
s that run Java apps are most likely to do so through support of the
Android operating system Android is a mobile operating system based on a modified version of the Linux kernel and other open-source software, designed primarily for touchscreen mobile devices such as smartphones and tablets. Android is developed by a consortium of d ...
, which includes an open source virtual machine incompatible with the JVM specification. (Instead,
Google Google LLC () is an American Multinational corporation, multinational technology company focusing on Search Engine, search engine technology, online advertising, cloud computing, software, computer software, quantum computing, e-commerce, ar ...
's Android development tools take Java programs as input and output Dalvik bytecode, which is the native input format for the virtual machine on Android devices.) The last Critical Path Update version of JRE with an Oracle BCL Agreement was 8u201 and, the last Patch Set Update version with the same license was 8u202. The last Oracle JRE implementation, regardless of its licensing scheme, was 9.0.4.Since Java Platform SE 9, the whole platform also was grouped into
modules Broadly speaking, modularity is the degree to which a system's components may be separated and recombined, often with the benefit of flexibility and variety in use. The concept of modularity is used primarily to reduce complexity by breaking a s ...
. The modularization of Java SE implementations allows developers to bundle their applications together with all the modules used by them, instead of solely relying on the presence of a suitable Java SE implementation in the user device.


Performance

The JVM specification gives a lot of leeway to implementors regarding the implementation details. Since Java 1.3, JRE from Oracle contains a JVM called HotSpot. It has been designed to be a high-performance JVM. To speed-up code execution, HotSpot relies on just-in-time compilation. To speed-up object allocation and garbage collection, HotSpot uses generational heap.


Generational heap

The ''Java virtual machine heap'' is the area of memory used by the JVM for
dynamic memory allocation Memory management is a form of resource management applied to computer memory. The essential requirement of memory management is to provide ways to dynamically allocate portions of memory to programs at their request, and free it for reuse when ...
. In HotSpot the heap is divided into ''generations'': * The ''young generation'' stores short-lived
objects Object may refer to: General meanings * Object (philosophy), a thing, being, or concept ** Object (abstract), an object which does not exist at any particular time or place ** Physical object, an identifiable collection of matter * Goal, an ai ...
that are created and immediately garbage collected. * Objects that persist longer are moved to the ''old generation'' (also called the ''tenured generation''). This memory is subdivided into (two) Survivors spaces where the objects that survived the first and next garbage collections are stored. The ''permanent generation'' (or ''permgen'') was used for class definitions and associated metadata prior to Java 8. Permanent generation was not part of the heap. The ''permanent generation'' was removed from Java 8. Originally there was no permanent generation, and objects and classes were stored together in the same area. But as class unloading occurs much more rarely than objects are collected, moving class structures to a specific area allowed significant performance improvements.


Security

Oracle's JRE is installed on a large number of computers. End users with an out-of-date version of JRE therefore are vulnerable to many known attacks. This led to the widely shared belief that Java is inherently insecure. Since Java 1.7, Oracle's JRE for Windows includes automatic update functionality. Before the discontinuation of the Java browser plug-in, any web page might have potentially run a Java applet, which provided an easily accessible
attack surface The attack surface of a software environment is the sum of the different points (for " attack vectors") where an unauthorized user (the "attacker") can try to enter data to or extract data from an environment. Keeping the attack surface as small a ...
to malicious web sites. In 2013 Kaspersky Labs reported that the Java plug-in was the method of choice for computer criminals. Java exploits are included in many exploit packs that hackers deploy onto hacked web sites. Java applets were removed in Java 11, released on September 25, 2018.


History

The Java platform and language began as an internal project at
Sun Microsystems Sun Microsystems, Inc. (Sun for short) was an American technology company that sold computers, computer components, software, and information technology services and created the Java programming language, the Solaris operating system, ZFS, t ...
in December 1990, providing an alternative to the C++/ C programming languages. Engineer
Patrick Naughton Patrick Naughton is an American software developer and convicted sex offender. He is one of the creators of the Java programming language. Career Early career In 1983, Naughton co-wrote a MacPaint clone, ''Painter's Apprentice'', with ...
had become increasingly frustrated with the state of Sun's C++ and C
application programming interface An application programming interface (API) is a way for two or more computer programs to communicate with each other. It is a type of software interface, offering a service to other pieces of software. A document or standard that describes how ...
s (APIs) and tools, as well as with the way the
NeWS News is information about current events. This may be provided through many different media: word of mouth, printing, postal systems, broadcasting, electronic communication, or through the testimony of observers and witnesses to event ...
project was handled by the organization. Naughton informed
Scott McNealy Scott McNealy (born November 13, 1954) is an American businessman. He is most famous for co-founding the computer technology company Sun Microsystems in 1982 along with Vinod Khosla, Bill Joy, and Andy Bechtolsheim. In 2004, while still at Sun, ...
about his plan of leaving Sun and moving to
NeXT Next may refer to: Arts and entertainment Film * ''Next'' (1990 film), an animated short about William Shakespeare * ''Next'' (2007 film), a sci-fi film starring Nicolas Cage * '' Next: A Primer on Urban Painting'', a 2005 documentary film Lit ...
; McNealy asked him to pretend he was God and send him an e-mail explaining how to fix the company. Naughton envisioned the creation of a small team that could work autonomously without the bureaucracy that was stalling other Sun projects. McNealy forwarded the message to other important people at Sun, and the ''Stealth Project'' started. The Stealth Project was soon renamed to the ''Green Project'', with
James Gosling James Gosling (born May 19, 1955) is a Canadian computer scientist, best known as the founder and lead designer behind the Java programming language. Gosling was elected a member of the National Academy of Engineering in 2004 for the conception ...
and Mike Sheridan joining Naughton. Together with other engineers, they began work in a small office on
Sand Hill Road Sand Hill Road, often shortened to just "Sand Hill" or "SHR", is an arterial road in western Silicon Valley, California, running through Palo Alto, Menlo Park, and Woodside, notable for its concentration of venture capital companies. The road ...
in
Menlo Park, California Menlo Park is a city at the eastern edge of San Mateo County within the San Francisco Bay Area of California in the United States. It is bordered by San Francisco Bay on the north and east; East Palo Alto, Palo Alto, and Stanford to the south ...
. They aimed to develop new technology for programming next-generation smart appliances, which Sun expected to offer major new opportunities. The team originally considered using C++, but rejected it for several reasons. Because they were developing an
embedded system An embedded system is a computer system—a combination of a computer processor, computer memory, and input/output peripheral devices—that has a dedicated function within a larger mechanical or electronic system. It is ''embedded ...
with limited resources, they decided that C++ needed too much memory and that its complexity led to developer errors. The language's lack of
garbage collection Waste collection is a part of the process of waste management. It is the transfer of solid waste from the point of use and disposal to the point of treatment or landfill. Waste collection also includes the curbside collection of recyclabl ...
meant that programmers had to manually manage system memory, a challenging and error-prone task. The team also worried about the C++ language's lack of portable facilities for security,
distributed programming A distributed system is a system whose components are located on different networked computers, which communicate and coordinate their actions by passing messages to one another from any system. Distributed computing is a field of computer sc ...
, and threading. Finally, they wanted a platform that would port easily to all types of devices.
Bill Joy William Nelson Joy (born November 8, 1954) is an American computer engineer and venture capitalist. He co-founded Sun Microsystems in 1982 along with Scott McNealy, Vinod Khosla, and Andy Bechtolsheim, and served as Chief Scientist and CTO at ...
had envisioned a new language combining
Mesa A mesa is an isolated, flat-topped elevation, ridge or hill, which is bounded from all sides by steep escarpments and stands distinctly above a surrounding plain. Mesas characteristically consist of flat-lying soft sedimentary rocks capped by a ...
and C. In a paper called ''Further'', he proposed to Sun that its engineers should produce an
object-oriented Object-oriented programming (OOP) is a programming paradigm based on the concept of "objects", which can contain data and code. The data is in the form of fields (often known as attributes or ''properties''), and the code is in the form of ...
environment based on C++. Initially, Gosling attempted to modify and extend C++ (a proposed development that he referred to as "C++ ++ --") but soon abandoned that in favor of creating a new language, which he called '' Oak'', after the tree that stood just outside his office. By the summer of 1992, the team could demonstrate portions of the new platform, including the Green OS, the Oak language, the libraries, and the hardware. Their first demonstration, on September 3, 1992, focused on building a
personal digital assistant A personal digital assistant (PDA), also known as a handheld PC, is a variety mobile device which functions as a personal information manager. PDAs have been mostly displaced by the widespread adoption of highly capable smartphones, in part ...
(PDA) device named '' Star7'' that had a graphical interface and a smart agent called "Duke" to assist the user. In November of that year, the Green Project was spun off to become ''Firstperson'', a wholly owned subsidiary of Sun Microsystems, and the team relocated to
Palo Alto, California Palo Alto (; Spanish for "tall stick") is a charter city in the northwestern corner of Santa Clara County, California, United States, in the San Francisco Bay Area, named after a coastal redwood tree known as El Palo Alto. The city was es ...
. The Firstperson team had an interest in building highly interactive devices, and when
Time Warner Warner Media, LLC ( traded as WarnerMedia) was an American multinational mass media and entertainment conglomerate. It was headquartered at the 30 Hudson Yards complex in New York City, United States. It was originally established in 1972 by ...
issued a request for proposal (RFP) for a
set-top box A set-top box (STB), also colloquially known as a cable box and historically television decoder, is an information appliance device that generally contains a TV-tuner input and displays output to a television set and an external source of s ...
, Firstperson changed their target and responded with a proposal for a set-top box platform. However, the
cable Cable may refer to: Mechanical * Nautical cable, an assembly of three or more ropes woven against the weave of the ropes, rendering it virtually waterproof * Wire rope, a type of rope that consists of several strands of metal wire laid into a hel ...
industry felt that their platform gave too much control to the user, so Firstperson lost their bid to SGI. An additional deal with
The 3DO Company The 3DO Company (formerly THDO on the NASDAQ stock exchange), also known as 3DO, was an American video game company. It was founded in 1991 by Electronic Arts founder Trip Hawkins, in a partnership with seven other companies. After 3DO's flagsh ...
for a set-top box also failed to materialize. Unable to generate interest within the television industry, the company was rolled back into Sun.


Java meets the Web

In June and July 1994 after three days of brainstorming with John Gage (the Director of Science for Sun), Gosling, Joy, Naughton, Wayne Rosing, and
Eric Schmidt Eric Emerson Schmidt (born April 27, 1955) is an American businessman and software engineer known for being the CEO of Google from 2001 to 2011, executive chairman of Google from 2011 to 2015, executive chairman of Alphabet Inc. from 2015 to 2 ...
the team re-targeted the platform for the
World Wide Web The World Wide Web (WWW), commonly known as the Web, is an information system enabling documents and other web resources to be accessed over the Internet. Documents and downloadable media are made available to the network through web ...
. They felt that with the advent of graphical
web browser A web browser is application software for accessing websites. When a user requests a web page from a particular website, the browser retrieves its files from a web server and then displays the page on the user's screen. Browsers are used o ...
s like
Mosaic A mosaic is a pattern or image made of small regular or irregular pieces of colored stone, glass or ceramic, held in place by plaster/mortar, and covering a surface. Mosaics are often used as floor and wall decoration, and were particularly pop ...
the Internet could evolve into the same highly interactive medium that they had envisioned for cable TV. As a prototype, Naughton wrote a small browser, WebRunner (named after the movie ''
Blade Runner ''Blade Runner'' is a 1982 science fiction film directed by Ridley Scott, and written by Hampton Fancher and David Peoples. Starring Harrison Ford, Rutger Hauer, Sean Young, and Edward James Olmos, it is an adaptation of Philip K. Dick's ...
''), renamed HotJava in 1995. Sun renamed the Oak language to ''Java'' after a
trademark A trademark (also written trade mark or trade-mark) is a type of intellectual property consisting of a recognizable sign, design, or expression that identifies products or services from a particular source and distinguishes them from ot ...
search revealed that
Oak Technology Oak Technology was an American supplier of semiconductor chips for sound cards, graphics cards and optical storage devices such as CD-ROM, CD-RW and DVD. It achieved success with optical storage chips and its stock price increased substantially ...
used the name ''Oak''. Sun priced Java licenses below cost to gain market share. Although Java 1.0a became available for download in 1994, the first public release of Java, Java 1.0a2 with the HotJava browser, came on May 23, 1995, announced by Gage at the SunWorld conference. Accompanying Gage's announcement,
Marc Andreessen Marc Lowell Andreessen ( ; born July 9, 1971) is an American entrepreneur, investor, and software engineer. He is the co-author of Mosaic, the first widely used web browser; co-founder of Netscape; and co-founder and general partner of Silico ...
, Executive Vice President of
Netscape Communications Corporation Netscape Communications Corporation (originally Mosaic Communications Corporation) was an American independent computer services company with headquarters in Mountain View, California and then Dulles, Virginia. Its Netscape web browser was onc ...
, unexpectedly announced that Netscape browsers would include Java support. On January 9, 1996, Sun Microsystems formed the JavaSoft group to develop the technology. While the so-called Java applets for web browsers no longer are the most popular use of Java (with it e.g. more used server-side) or the most popular way to run code client-side (JavaScript took over as more popular), it still is possible to run Java (or other JVM-languages such as Kotlin) in web browsers, even after JVM-support has been dropped from them, using e.g.
TeaVM 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 describes ...
.


Version history

The Java language has undergone several changes since the release of JDK (
Java Development Kit The Java Development Kit (JDK) is a distribution of Java Technology by Oracle Corporation. It implements the Java Language Specification (JLS) and the Java Virtual Machine Specification (JVMS) and provides the Standard Edition (SE) of the Java ...
) 1.0 on January 23, 1996, as well as numerous additions of classes and packages to the standard
library A library is a collection of materials, books or media that are accessible for use and not just for display purposes. A library provides physical (hard copies) or digital access (soft copies) materials, and may be a physical location or a vi ...
. Since J2SE 1.4 the
Java Community Process The Java Community Process (JCP), established in 1998, is a formalized mechanism that allows interested parties to develop standard technical specifications for Java technology. Anyone can become a JCP Member by filling a form available at thJCP w ...
(JCP) has governed the evolution of the Java Language. The JCP uses ''Java Specification Requests'' (JSRs) to propose and specify additions and changes to the Java platform. The ''Java Language Specification'' (JLS) specifies the language; changes to the JLS are managed under JSR 901. Sun released ''JDK 1.1'' on February 19, 1997. Major additions included an extensive retooling of the AWT event model, inner classes added to the language,
JavaBean In computing based on the Java Platform, JavaBeans is a technology developed by Sun Microsystems and released in 1996, as part of JDK 1.1. The 'beans' of JavaBeans are classes that encapsulate one or more objects into a single standardized objec ...
s and
JDBC Java Database Connectivity (JDBC) is an application programming interface (API) for the programming language Java, which defines how a client may access a database. It is a Java-based data access technology used for Java database connectivity. I ...
. ''J2SE 1.2'' (December 8, 1998) – Codename ''Playground''. This and subsequent releases through J2SE 5.0 were rebranded ''Java 2'' and the version name "J2SE" ( Java 2 Platform, Standard Edition) replaced JDK to distinguish the base platform from J2EE ( Java 2 Platform, Enterprise Edition) and J2ME ( Java 2 Platform, Micro Edition). Major additions included
reflection Reflection or reflexion may refer to: Science and technology * Reflection (physics), a common wave phenomenon ** Specular reflection, reflection from a smooth surface *** Mirror image, a reflection in a mirror or in water ** Signal reflection, in ...
, a
collections Collection or Collections may refer to: * Cash collection, the function of an accounts receivable department * Collection (church), money donated by the congregation during a church service * Collection agency, agency to collect cash * Collection ...
framework, Java IDL (an
interface description language interface description language or interface definition language (IDL), is a generic term for a language that lets a program or object written in one language communicate with another program written in an unknown language. IDLs describe an inter ...
implementation for
CORBA The Common Object Request Broker Architecture (CORBA) is a standard defined by the Object Management Group (OMG) designed to facilitate the communication of systems that are deployed on diverse platforms. CORBA enables collaboration between s ...
interoperability), and the integration of the
Swing Swing or swinging may refer to: Apparatus * Swing (seat), a hanging seat that swings back and forth * Pendulum, an object that swings * Russian swing, a swing-like circus apparatus * Sex swing, a type of harness for sexual intercourse * Swing ri ...
graphical API into the core classes. A
Java Plug-in Java applets were small applications written in the Java programming language, or another programming language that compiles to Java bytecode, and delivered to users in the form of Java bytecode. The user launched the Java applet from ...
was released, and Sun's JVM was equipped with a JIT compiler for the first time. ''J2SE 1.3'' (May 8, 2000) – Codename ''Kestrel''. Notable changes included the bundling of the HotSpot JVM (the HotSpot JVM was first released in April, 1999 for the J2SE 1.2 JVM), JavaSound, Java Naming and Directory Interface (JNDI) and Java Platform Debugger Architecture (JPDA). ''J2SE 1.4'' (February 6, 2002) – Codename ''Merlin''. This became the first release of the Java platform developed under the Java Community Process as JSR 59. Major changes included
regular expressions A regular expression (shortened as regex or regexp; sometimes referred to as rational expression) is a sequence of characters that specifies a search pattern in text. Usually such patterns are used by string-searching algorithms for "find" o ...
modeled after
Perl Perl is a family of two high-level, general-purpose, interpreted, dynamic programming languages. "Perl" refers to Perl 5, but from 2000 to 2019 it also referred to its redesigned "sister language", Perl 6, before the latter's name was offic ...
, exception chaining, an integrated
XML Extensible Markup Language (XML) is a markup language and file format for storing, transmitting, and reconstructing arbitrary data. It defines a set of rules for encoding documents in a format that is both human-readable and machine-readable. T ...
parser and
XSLT XSLT (Extensible Stylesheet Language Transformations) is a language originally designed for transforming XML documents into other XML documents, or other formats such as HTML for web pages, plain text or XSL Formatting Objects, which may subseq ...
processor (
JAXP In computing, the Java API for XML Processing, or JAXP ( ), one of the Java XML Application programming interfaces, provides the capability of validating and parsing XML documents. It has three basic parsing interfaces: * the Document Object M ...
), and
Java Web Start In computing, Java Web Start (also known as JavaWS, javaws or JAWS) is a deprecated framework developed by Sun Microsystems (now Oracle) that allows users to start application software for the Java Platform directly from the Internet using a web b ...
. ''J2SE 5.0'' (September 30, 2004) – Codename ''Tiger''. It was originally numbered 1.5, which is still used as the internal version number. Developed under JSR 176, Tiger added several significant new language features including the for-each loop,
generics Generic or generics may refer to: In business * Generic term, a common name used for a range or class of similar things not protected by trademark * Generic brand, a brand for a product that does not have an associated brand or trademark, other ...
,
autoboxing In computer science, boxing (a.k.a. wrapping) is the transformation of placing a primitive type within an object so that the value can be used as a reference. Unboxing is the reverse transformation of extracting the primitive value from its wr ...
and var-args. ''Java SE 6'' (December 11, 2006) – Codename ''Mustang''. It was bundled with a database manager and facilitates the use of scripting languages with the JVM (such as
JavaScript JavaScript (), often abbreviated as JS, is a programming language that is one of the core technologies of the World Wide Web, alongside HTML and CSS. As of 2022, 98% of websites use JavaScript on the client side for webpage behavior, of ...
using
Mozilla Mozilla (stylized as moz://a) is a free software community founded in 1998 by members of Netscape. The Mozilla community uses, develops, spreads and supports Mozilla products, thereby promoting exclusively free software and open standards, ...
's Rhino engine). As of this version, Sun replaced the name "J2SE" with ''Java SE'' and dropped the ".0" from the version number. Other major changes include support for pluggable
annotations An annotation is extra information associated with a particular point in a document or other piece of information. It can be a note that includes a comment or explanation. Annotations are sometimes presented in the margin of book pages. For anno ...
( JSR 269), many
GUI The GUI ( "UI" by itself is still usually pronounced . or ), graphical user interface, is a form of user interface that allows users to interact with electronic devices through graphical icons and audio indicator such as primary notation, inste ...
improvements, including native UI enhancements to support the look and feel of
Windows Vista Windows Vista is a major release of the Windows NT operating system developed by Microsoft. It was the direct successor to Windows XP, which was released five years before, at the time being the longest time span between successive releases of ...
, and improvements to the Java Platform Debugger Architecture (JPDA) & JVM Tool Interface for better monitoring and troubleshooting. ''Java SE 7'' (July 28, 2011) – Codename ''Dolphin''. This version developed under JSR 336. It added many small language changes including strings in switch, try-with-resources and
type inference Type inference refers to the automatic detection of the type of an expression in a formal language. These include programming languages and mathematical type systems, but also natural languages in some branches of computer science and linguistic ...
for generic instance creation. The JVM was extended with support for dynamic languages, while the class library was extended among others with a join/fork framework, an improved new file I/O library and support for new network protocols such as
SCTP The Stream Control Transmission Protocol (SCTP) is a computer networking communications protocol in the transport layer of the Internet protocol suite. Originally intended for Signaling System 7 (SS7) message transport in telecommunication, the p ...
. Java 7 Update 76 was released in January 2015, with expiration date April 14, 2015. In June 2016, after the last public update of Java 7, " remotely exploitable" security bugs in Java 6, 7, and 8 were announced. ''Java SE 8'' (March 18, 2014) Codename ''Kenai''. Notable changes include language-level support for lambda expressions ( closures) and default methods, the Project Nashorn JavaScript runtime, a new Date and Time API inspired by Joda Time, and the removal of PermGen. This version is not officially supported on the Windows XP platform. However, due to the end of Java 7's lifecycle it is the recommended version for XP users. Previously, only an unofficial manual installation method had been described for Windows XP SP3. It refers to JDK8, the developing platform for Java that also includes a fully functioning
Java Runtime Environment Java is a set of computer software and specifications developed by James Gosling at Sun Microsystems, which was later acquired by the Oracle Corporation, that provides a system for developing application software and deploying it in a cros ...
. Java 8 is supported on Windows Server 2008 R2 SP1, Windows Vista SP2 and Windows 7 SP1, Ubuntu 12.04 LTS and higher (and some other OSes). ''Java SE 9'' and ''10'' had higher system requirements, i.e. Windows 7 or Server 2012 (and web browser minimum certified is upped to
Internet Explorer 11 Internet Explorer 11 (IE11) is the eleventh, final, and now deprecated version of the Internet Explorer web browser. It was initially included in the release of Windows 8.1, Windows RT 8.1 and Windows Server 2012 R2 on October 17, 2013, and was ...
or other web browsers), and Oracle dropped
32-bit In computer architecture, 32-bit computing refers to computer systems with a processor, memory, and other major system components that operate on data in 32- bit units. Compared to smaller bit widths, 32-bit computers can perform large calculati ...
compatibility for all platforms, i.e. only Oracle's "
64-bit In computer architecture, 64-bit integers, memory addresses, or other data units are those that are 64 bits wide. Also, 64-bit CPUs and ALUs are those that are based on processor registers, address buses, or data buses of that size. A ...
Java virtual machines (JVMs) are certified". ''Java SE 11'' was released September 2018, the first LTS release since the rapid release model was adopted starting with version 9. For the first time, OpenJDK 11 represents the complete source code for the Java platform under the GNU General Public License, and while Oracle still dual-licenses it with an optional proprietary license, there are no code differences nor modules unique to the proprietary-licensed version. Java 11 features include two new garbage collector implementations, Flight Recorder to debug deep issues, a new HTTP client including
WebSocket WebSocket is a computer communications protocol, providing full-duplex communication channels over a single TCP connection. The WebSocket protocol was standardized by the IETF as in 2011. The current API specification allowing web applications ...
support. ''Java SE 12'' was released March 2019. ''Java SE 13'' was released September 2019. ''Java SE 14'' was released March 2020. ''Java SE 15'' was released September 2020. ''Java SE 16'' was released March 2021. ''Java SE 17'' was released September 2021. ''Java SE 18'' was released March 2022. ''Java SE 19'' was released September 2022. In addition to language changes, significant changes have been made to the Java class library over the years, which has grown from a few hundred classes in JDK 1.0 to over three thousand in J2SE 5.0. Entire new APIs, such as
Swing Swing or swinging may refer to: Apparatus * Swing (seat), a hanging seat that swings back and forth * Pendulum, an object that swings * Russian swing, a swing-like circus apparatus * Sex swing, a type of harness for sexual intercourse * Swing ri ...
and Java 2D, have evolved, and many of the original JDK 1.0 classes and methods have been
deprecated In several fields, especially computing, deprecation is the discouragement of use of some terminology, feature, design, or practice, typically because it has been superseded or is no longer considered efficient or safe, without completely removing ...
.


Usage


Desktop use

According to Oracle in 2010, the Java Runtime Environment was found on over 850 million PCs.
Microsoft Microsoft Corporation is an American multinational technology corporation producing computer software, consumer electronics, personal computers, and related services headquartered at the Microsoft Redmond campus located in Redmond, Washi ...
has not bundled a
Java Runtime Environment Java is a set of computer software and specifications developed by James Gosling at Sun Microsystems, which was later acquired by the Oracle Corporation, that provides a system for developing application software and deploying it in a cros ...
(JRE) with its
operating system An operating system (OS) is system software that manages computer hardware, software resources, and provides common daemon (computing), services for computer programs. Time-sharing operating systems scheduler (computing), schedule tasks for ef ...
s since Sun Microsystems sued Microsoft for adding Windows-specific classes to the bundled Java runtime environment, and for making the new classes available through
Visual J++ Visual J++ is Microsoft's discontinued implementation of Java. Syntax, keywords, and grammatical conventions were the same as Java's. It was introduced in 1996 and discontinued in January 2004, replaced to a certain extent by J# and C#. The i ...
. Apple no longer includes a Java runtime with
OS X macOS (; previously OS X and originally Mac OS X) is a Unix operating system developed and marketed by Apple Inc. since 2001. It is the primary operating system for Apple's Mac computers. Within the market of desktop and la ...
as of version 10.7, but the system prompts the user to download and install it the first time an application requiring the JRE is launched. Many
Linux distribution A Linux distribution (often abbreviated as distro) is an operating system made from a software collection that includes the Linux kernel and, often, a package management system. Linux users usually obtain their operating system by downloading one ...
s include the
OpenJDK OpenJDK (Open Java Development Kit) is a free and open-source implementation of the Java Platform, Standard Edition (Java SE). It is the result of an effort Sun Microsystems began in 2006. The implementation is licensed under the GPL-2.0-only w ...
runtime as the default virtual machine, negating the need to download the proprietary Oracle JRE. Some Java applications are in fairly widespread desktop use, including the
NetBeans NetBeans is an integrated development environment (IDE) for Java. NetBeans allows applications to be developed from a set of modular software components called ''modules''. NetBeans runs on Windows, macOS, Linux and Solaris. In addition to Java ...
and
Eclipse An eclipse is an astronomical event that occurs when an astronomical object or spacecraft is temporarily obscured, by passing into the shadow of another body or by having another body pass between it and the viewer. This alignment of three c ...
integrated development environment An integrated development environment (IDE) is a software application that provides comprehensive facilities to computer programmers for software development. An IDE normally consists of at least a source code editor, build automation tools ...
s, and file sharing clients such as
LimeWire LimeWire was a free peer-to-peer file sharing client for Windows, MacOS, Linux and Solaris. Created by Mark Gorton in 2000, it was most prominently a tool used for the download and distribution of pirated materials, particularly pirated mus ...
and
Vuze Vuze (previously Azureus) is a BitTorrent client used to transfer files via the BitTorrent protocol. Vuze is written in Java, and uses the Azureus Engine. In addition to downloading data linked to .torrent files, Azureus allows users to view, p ...
. Java is also used in the
MATLAB MATLAB (an abbreviation of "MATrix LABoratory") is a proprietary multi-paradigm programming language and numeric computing environment developed by MathWorks. MATLAB allows matrix manipulations, plotting of functions and data, implementat ...
mathematics programming environment, both for rendering the
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 f ...
and as part of the core system. Java provides cross platform user interface for some high end collaborative applications such as
Lotus Notes HCL Notes (formerly IBM Notes and Lotus Notes; see Branding below) and HCL Domino (formerly IBM Domino and Lotus Domino) are the client and server Server may refer to: Computing *Server (computing), a computer program or a device that provide ...
. Oracle plans to first deprecate the separately installable Java browser plugin from the Java Runtime Environment in JDK 9 then remove it completely from a future release, forcing web developers to use an alternative technology.


Mascot

Duke is Java's
mascot A mascot is any human, animal, or object thought to bring luck, or anything used to represent a group with a common public identity, such as a school, professional sports team, society, military unit, or brand name. Mascots are also used as ...
. When Sun announced that
Java SE Java Platform, Standard Edition (Java SE) is a computing platform for development and deployment of portable code for desktop and server environments. Java SE was formerly known as Java 2 Platform, Standard Edition (J2SE). The platform uses Ja ...
and
Java ME Java Platform, Micro Edition or Java ME is a computing platform for development and deployment of portable code for embedded and mobile devices (micro-controllers, sensors, gateways, mobile phones, personal digital assistants, TV set-top ...
would be released under a
free software license A free-software license is a notice that grants the recipient of a piece of software extensive rights to modify and redistribute that software. These actions are usually prohibited by copyright law, but the rights-holder (usually the author) ...
(the
GNU General Public License The GNU General Public License (GNU GPL or simply GPL) is a series of widely used free software licenses that guarantee end users the four freedoms to run, study, share, and modify the software. The license was the first copyleft for general ...
), they released the Duke graphics under the free
BSD license BSD licenses are a family of permissive free software licenses, imposing minimal restrictions on the use and distribution of covered software. This is in contrast to copyleft licenses, which have share-alike requirements. The original BSD lice ...
at the same time. A new Duke personality is created every year. For example, in July 2011 "Future Tech Duke" included a bigger nose, a jetpack, and blue wings.


Licensing

The source code for Sun's implementations of Java (i.e. the de facto reference implementation) has been available for some time, but until recently, the license terms severely restricted what could be done with it without signing (and generally paying for) a contract with Sun. As such these terms did not satisfy the requirements of either the
Open Source Initiative The Open Source Initiative (OSI) is the steward of the Open Source Definition, the set of rules that define open source software. It is a California public-benefit nonprofit corporation, with 501(c)(3) tax-exempt status. The organization wa ...
or the
Free Software Foundation The Free Software Foundation (FSF) is a 501(c)(3) non-profit organization founded by Richard Stallman on October 4, 1985, to support the free software movement, with the organization's preference for software being distributed under copyleft ( ...
to be considered open source or free software, and Sun Java was therefore a proprietary platform. While several third-party projects (e.g.
GNU Classpath GNU Classpath is a free software implementation of the standard class library for the Java programming language. Most classes from J2SE 1.4 and 5.0 are implemented. Classpath can thus be used to run Java-based applications. GNU Classpath is a p ...
and
Apache Harmony Apache Harmony is a retired open source, free Java implementation, developed by the Apache Software Foundation. It was announced in early May 2005 and on October 25, 2006, the Board of Directors voted to make Apache Harmony a top-level project ...
) created
free software Free software or libre software is computer software distributed under terms that allow users to run the software for any purpose as well as to study, change, and distribute it and any adapted versions. Free software is a matter of liberty, n ...
partial Java implementations, the large size of the Sun libraries combined with the use of clean room methods meant that their implementations of the Java libraries (the compiler and VM are comparatively small and well defined) were incomplete and not fully compatible. These implementations also tended to be far less optimized than Sun's.


Free software

Sun The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...
announced in
JavaOne __NOTOC__ JavaOne is an annual conference first organized in 1996 by Sun Microsystems to discuss Java technologies, primarily among Java developers. It was held in San Francisco, California, typically running from a Monday to Thursday in summer ...
2006 that Java would become free and
open source software Open-source software (OSS) is computer software that is released under a license in which the copyright holder grants users the rights to use, study, change, and distribute the software and its source code to anyone and for any purpose. Open ...
, and on October 25, 2006, at the Oracle OpenWorld conference, Jonathan I. Schwartz said that the company was set to announce the release of the core
Java Platform Java is a set of computer software and specifications developed by James Gosling at Sun Microsystems, which was later acquired by the Oracle Corporation, that provides a system for developing application software and deploying it in a cro ...
as free and open source software within 30 to 60 days. Sun released the Java HotSpot virtual machine and compiler as free software under the
GNU General Public License The GNU General Public License (GNU GPL or simply GPL) is a series of widely used free software licenses that guarantee end users the four freedoms to run, study, share, and modify the software. The license was the first copyleft for general ...
on November 13, 2006, with a promise that the rest of the JDK (that includes the JRE) would be placed under the GPL by March 2007 ("except for a few components that Sun does not have the right to publish in distributable source form under the GPL"). According to
Richard Stallman Richard Matthew Stallman (; born March 16, 1953), also known by his initials, rms, is an American free software movement activist and programmer. He campaigns for software to be distributed in such a manner that its users have the freedom to ...
, this would mean an end to the "Java trap".
Mark Shuttleworth Mark Richard Shuttleworth (born 18 September 1973) is a South African and British entrepreneur who is the founder and CEO of Canonical, the company behind the development of the Linux-based Ubuntu operating system. In 2002, Shuttleworth became ...
called the initial press announcement, "A real milestone for the
free software Free software or libre software is computer software distributed under terms that allow users to run the software for any purpose as well as to study, change, and distribute it and any adapted versions. Free software is a matter of liberty, n ...
community". Sun released the
source code In computing, source code, or simply code, is any collection of code, with or without comments, written using a human-readable programming language, usually as plain text. The source code of a program is specially designed to facilitate the ...
of the
Class library In computer science, a library is a collection of non-volatile resources used by computer programs, often for software development. These may include configuration data, documentation, help data, message templates, pre-written code and subro ...
under GPL on May 8, 2007, except some limited parts that were licensed by Sun from third parties who did not want their code to be released under a free software and open-source license. Some of the encumbered parts turned out to be fairly key parts of the platform such as font rendering and 2D rasterising, but these were released as open-source later by Sun (see OpenJDK Class library). Sun's goal was to replace the parts that remain proprietary and closed-source with alternative implementations and make the class library completely free and open source. In the meantime, a third-party project called IcedTea created a completely free and highly usable JDK by replacing encumbered code with either stubs or code from
GNU Classpath GNU Classpath is a free software implementation of the standard class library for the Java programming language. Most classes from J2SE 1.4 and 5.0 are implemented. Classpath can thus be used to run Java-based applications. GNU Classpath is a p ...
. However OpenJDK has since become buildable without the encumbered parts (from OpenJDK 6 b10) and has become the default runtime environment for most Linux distributions. In June 2008, it was announced that IcedTea6 (as the packaged version of OpenJDK on Fedora 9) has passed the
Technology Compatibility Kit A Technology Compatibility Kit (TCK) is a suite of tests that at least nominally checks a particular alleged implementation of a Java Specification Request (JSR) for compliance. It is one of the three required pieces for a ratified JSR in the Java ...
tests and can claim to be a fully compatible Java 6 implementation. Because OpenJDK is under the GPL, it is possible to redistribute a custom version of the JRE directly with software applications, rather than requiring the enduser (or their sysadmin) to download and install the correct version of the proprietary Oracle JRE onto each of their systems themselves.


Criticism

In most cases, Java support is unnecessary in Web browsers, and security experts recommend that it not be run in a browser unless absolutely necessary. It was suggested that, if Java is required by a few Web sites, users should have a separate browser installation specifically for those sites.


Generics

When
generics Generic or generics may refer to: In business * Generic term, a common name used for a range or class of similar things not protected by trademark * Generic brand, a brand for a product that does not have an associated brand or trademark, other ...
were added to Java 5.0, there was already a large framework of classes (many of which were already
deprecated In several fields, especially computing, deprecation is the discouragement of use of some terminology, feature, design, or practice, typically because it has been superseded or is no longer considered efficient or safe, without completely removing ...
), so generics were chosen to be implemented using
erasure Erasure () is an English synth-pop duo formed in London in 1985, consisting of lead vocalist and songwriter Andy Bell with songwriter, producer and keyboardist Vince Clarke, previously known as co-founder of the band Depeche Mode and a membe ...
to allow for ''migration compatibility'' and re-use of these existing classes. This limited the features that could be provided by this addition as compared to some other languages. The addition of type wildcards made Java unsound.


Unsigned integer types

Java lacks native
unsigned integer In computer science, an integer is a datum of integral data type, a data type that represents some range of mathematical integers. Integral data types may be of different sizes and may or may not be allowed to contain negative values. Integers are ...
types. Unsigned data are often generated from programs written in C and the lack of these types prevents direct data interchange between C and Java. Unsigned large numbers are also used in many numeric processing fields, including cryptography, which can make Java less convenient to use for these tasks. Although it is possible to partially circumvent this problem with conversion code and using larger data types, it makes using Java cumbersome for handling the unsigned data. While a 32-bit signed integer may be used to hold a 16-bit unsigned value with relative ease, a 32-bit unsigned value would require a 64-bit signed integer. Additionally, a 64-bit unsigned value cannot be stored using any integer type in Java because no type larger than 64 bits exists in the Java language. If abstracted using functions, function calls become necessary for many operations which are native to some other languages. Alternatively, it is possible to use Java's signed integers to emulate unsigned integers of the same size, but this requires detailed knowledge of complex bitwise operations.


Floating point arithmetic

While Java's floating point arithmetic is largely based on
IEEE 754 The IEEE Standard for Floating-Point Arithmetic (IEEE 754) is a technical standard for floating-point arithmetic established in 1985 by the Institute of Electrical and Electronics Engineers (IEEE). The standard addressed many problems found ...
(''Standard for Binary Floating-Point Arithmetic''), certain features are not supported even when using the
strictfp strictfp is an obsolete and unused reserved word in the Java programming language. Previously, this keyword was used as a modifier that restricted floating-point calculations to IEEE 754 semantics in order to ensure portability. The strictfp keywor ...
modifier, such as Exception Flags and Directed Roundings capabilities mandated by IEEE Standard 754. Additionally, the extended precision floating-point types permitted in 754 and present in many processors are not permitted in Java.


Performance

In the early days of Java (before the HotSpot VM was implemented in Java 1.3 in 2000) there were some criticisms of performance. Benchmarks typically reported Java as being about 50% slower than C (a language which compiles to native code).Which programming languages are fastest? , Computer Language Benchmarks Game
Java's performance has improved substantially since the early versions. Performance of JIT compilers relative to native compilers has in some optimized tests been shown to be quite similar.FreeTTS – A Performance Case Study
, Willie Walker, Paul Lamere, Philip Kwok
Java bytecode In computing, Java bytecode is the bytecode-structured instruction set of the Java virtual machine (JVM), a virtual machine that enables a computer to run programs written in the Java programming language and several other programming langua ...
can either be interpreted at run time by a virtual machine, or it can be compiled at load time or runtime into native code which runs directly on the computer's hardware. Interpretation is slower than native execution, and compilation at load time or runtime has an initial performance penalty for the compilation. Modern performant JVM implementations all use the compilation approach, so after the initial startup time the performance is equivalent to native code.


Security

The Java platform provides a security architecture which is designed to allow the user to run untrusted bytecode in a "sandboxed" manner to protect against malicious or poorly written software. This "sandboxing" feature is intended to protect the user by restricting access to certain platform features and APIs which could be exploited by
malware Malware (a portmanteau for ''malicious software'') is any software intentionally designed to cause disruption to a computer, server, client, or computer network, leak private information, gain unauthorized access to information or systems, depr ...
, such as accessing the local filesystem, running arbitrary commands, or accessing communication networks. In recent years, researchers have discovered numerous security flaws in some widely used Java implementations, including Oracle's, which allow untrusted code to bypass the sandboxing mechanism, exposing users to malicious attacks. These flaws affect only Java applications which execute arbitrary untrusted bytecode, such as web browser plug-ins that run Java applets downloaded from public websites. Applications where the user trusts, and has full control over, all code that is being executed are unaffected. On August 31, 2012, Java 6 and 7 (both supported back then) on Microsoft Windows,
OS X macOS (; previously OS X and originally Mac OS X) is a Unix operating system developed and marketed by Apple Inc. since 2001. It is the primary operating system for Apple's Mac computers. Within the market of desktop and la ...
, and Linux were found to have a serious security flaw that allowed a remote exploit to take place by simply loading a malicious web page. was later found to be flawed as well. On January 10, 2013, three computer specialists spoke out against Java, telling
Reuters Reuters ( ) is a news agency owned by Thomson Reuters Corporation. It employs around 2,500 journalists and 600 photojournalists in about 200 locations worldwide. Reuters is one of the largest news agencies in the world. The agency was est ...
that it was not secure and that people should disable Java. Jaime Blasco, Labs Manager with AlienVault Labs, stated that "Java is a mess. It's not secure. You have to disable it." This vulnerability affects and it is unclear if it affects , so it is suggested that consumers disable it. Security alerts from Oracle announce schedules of critical security-related patches to Java. On January 14, 2013, security experts said that the update still failed to protect PCs from attack. This exploit hole prompted a response from the
United States Department of Homeland Security The United States Department of Homeland Security (DHS) is the U.S. federal executive department responsible for public security, roughly comparable to the interior or home ministries of other countries. Its stated missions involve anti-ter ...
encouraging users to disable or uninstall Java. Apple blacklisted Java in limited order for all computers running its
OS X macOS (; previously OS X and originally Mac OS X) is a Unix operating system developed and marketed by Apple Inc. since 2001. It is the primary operating system for Apple's Mac computers. Within the market of desktop and la ...
operating system through a virus protection program. In 2014 and responding to then-recent Java security and vulnerability issues, security blogger
Brian Krebs Brian Krebs (born 1972) is an American journalist and investigative reporter. He is best known for his coverage of profit-seeking cybercriminals.Perlroth, Nicole.Reporting From the Web's Underbelly. ''The New York Times''. Retrieved February 28, ...
has called for users to remove at least the Java browser plugin and also the entire software. "I look forward to a world without the Java plugin (and to not having to remind readers about quarterly patch updates) but it will probably be years before various versions of this plugin are mostly removed from end-user systems worldwide." "Once promising, it has outlived its usefulness in the browser, and has become a nightmare that delights cyber-criminals at the expense of computer users." "I think everyone should uninstall Java from all their PCs and Macs, and then think carefully about whether they need to add it back. If you are a typical home user, you can probably do without it. If you are a business user, you may not have a choice."


Adware

The Oracle-distributed Java runtime environment has a history of bundling sponsored software to be installed by default during installation and during the updates which roll out every month or so. This includes the "
Ask.com toolbar Ask.com (originally known as Ask Jeeves) is a question answering–focused e-business founded in 1996 by Garrett Gruener and David Warthen in Berkeley, California, Berkeley, California. The original software was implemented by Gary Chevsky, from ...
" that will redirect browser searches to ads and "McAfee Security Scan Plus". These offers can be blocked through a setting in the Java Control Panel, although this is not obvious. This setting is located under the "Advanced" tab in the Java Control Panel, under the "Miscellaneous" heading, where the option is labelled as an option to suppress "sponsor offers".


Update system

Java has yet to release an automatic updater that does not require user intervention and administrative rights unlike Google Chrome and Flash player.


See also

*
List of Java APIs There are two types of Java programming language application programming interfaces (APIs): * The official core Java API, contained in the Android (Google), SE (OpenJDK and Oracle), MicroEJ. These packages (java.* packages) are the core Java la ...
*
Java logging frameworks A Java logging framework is a computer data logging package for the Java platform. This article covers general purpose logging frameworks. Logging refers to the recording of activity by an application and is a common issue for development teams. ...
* Java performance *
JavaFX JavaFX is a software platform for creating and delivering desktop applications, as well as rich web applications that can run across a wide variety of devices. JavaFX has support for desktop computers and web browsers on Microsoft Windows, Linu ...
*
Jazelle Jazelle DBX (direct bytecode execution) is an extension that allows some ARM processors to execute Java bytecode in hardware as a third execution state alongside the existing ARM and Thumb modes. Jazelle functionality was specified in the ARMv5TEJ ...
* Java ConcurrentMap *
Comparison of the Java and .NET platforms Comparison of the Java and .NET platforms. Legal issues .NET The Mono project aims to avoid infringing on any patents or copyrights and, to the extent that they are successful, the project can be safely distributed and used under the GPL. On N ...
*
List of JVM languages This list of JVM Languages comprises notable computer programming languages that are used to produce computer software that runs on the Java virtual machine (JVM). Some of these languages are interpreted by a Java program, and some are compi ...
* List of computing mascots


References


External links

*
sun.com – Official developer site
* Presentation by
James Gosling James Gosling (born May 19, 1955) is a Canadian computer scientist, best known as the founder and lead designer behind the Java programming language. Gosling was elected a member of the National Academy of Engineering in 2004 for the conception ...
about the origins of Java, from the JVM Languages Summit 2008
Java forums organization

Java Introduction
May 14, 2014, Java77 Blog {{Oracle FOSS Computing platforms Cross-platform software