Clojure ( / ˈ k l oʊ ʒ ər / , like closure ) is a dynamic and functional dialect of the programming language Lisp on the Java platform.
85-399: Like most other Lisps, Clojure's syntax is built on S-expressions that are first parsed into data structures by a Lisp reader before being compiled . Clojure's reader supports literal syntax for maps , sets, and vectors along with lists, and these are compiled to the mentioned structures directly. Clojure treats code as data and has a Lisp macro system. Clojure is a Lisp-1 and
170-411: A BEGIN statement, and Perl function prototypes may alter the syntactic interpretation, and possibly even the syntactic validity of the remaining code. Colloquially this is referred to as "only Perl can parse Perl" (because code must be executed during parsing, and can modify the grammar), or more strongly "even Perl cannot parse Perl" (because it is undecidable). Similarly, Lisp macros introduced by
255-439: A concrete syntax tree; the parser writer must then manually write code describing how this is converted to an abstract syntax tree. Contextual analysis is also generally implemented manually. Despite the existence of these automatic tools, parsing is often implemented manually, for various reasons – perhaps the phrase structure is not context-free, or an alternative implementation improves performance or error-reporting, or allows
340-572: A regular language , specified in the lexical grammar , which is a Type-3 grammar, generally given as regular expressions . Phrases are in a context-free language (CFL), generally a deterministic context-free language (DCFL), specified in a phrase structure grammar , which is a Type-2 grammar, generally given as production rules in Backus–Naur form (BNF). Phrase grammars are often specified in much more constrained grammars than full context-free grammars , in order to make them easier to parse; while
425-470: A symbol table which stores names and types for each scope. Tools have been written that automatically generate a lexer from a lexical specification written in regular expressions and a parser from the phrase grammar written in BNF: this allows one to use declarative programming , rather than need to have procedural or functional programming. A notable example is the lex - yacc pair. These automatically produce
510-405: A Lisp dialect, Clojure supports functions as first-class objects , a read–eval–print loop (REPL), and a macro system. Clojure's Lisp macro system is very similar to that of Common Lisp with the exception that Clojure's version of the backquote (termed "syntax quote") qualifies symbols with their namespace . This helps prevent unintended name capture, as binding to namespace-qualified names
595-402: A Type-2 grammar, i.e., they are context-free grammars , though the overall syntax is context-sensitive (due to variable declarations and nested scopes), hence Type-1. However, there are exceptions, and for some languages the phrase grammar is Type-0 (Turing-complete). In some languages like Perl and Lisp the specification (or implementation) of the language allows constructs that execute during
680-400: A combination of symbols is handled by semantics (either formal or hard-coded in a reference implementation ). Valid syntax must be established before semantics can make meaning out of it. Not all syntactically correct programs are semantically correct. Many syntactically correct programs are nonetheless ill-formed, per the language's rules; and may (depending on the language specification and
765-399: A designer might start by writing down examples of both legal and illegal strings , before trying to figure out the general rules from these examples. Syntax therefore refers to the form of the code, and is contrasted with semantics – the meaning . In processing computer languages, semantic processing generally comes after syntactic processing; however, in some cases, semantic processing
850-583: A half years working on Clojure before releasing it publicly in October 2007, much of that time working exclusively on Clojure with no outside funding. At the end of this time, Hickey sent an email announcing the language to some friends in the Common Lisp community. Clojure's name, according to Hickey, is a word play on the programming concept " closure " incorporating the letters C, L, and J for C# , Lisp , and Java respectively—three languages which had
935-717: A lawsuit against Google shortly after that for using Java inside the Android SDK (see the Android section). On April 2, 2010, James Gosling resigned from Oracle . In January 2016, Oracle announced that Java run-time environments based on JDK 9 will discontinue the browser plugin. Java software runs on everything from laptops to data centers , game consoles to scientific supercomputers . Oracle (and others) highly recommend uninstalling outdated and unsupported versions of Java, due to unresolved security issues in older versions. There were five primary goals in creating
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#17327722569411020-424: A lexer turns the linear sequence of characters into a linear sequence of tokens; this is known as " lexical analysis " or "lexing". Second, the parser turns the linear sequence of tokens into a hierarchical syntax tree; this is known as " parsing " narrowly speaking. This ensures that the line of tokens conform to the formal grammars of the programming language. The parsing stage itself can be divided into two parts:
1105-460: A look at the list of "Hello, World!" program examples: 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 anywhere ( WORA ), meaning that compiled Java code can run on all platforms that support Java without
1190-558: A major influence on Clojure's design. Rich Hickey developed Clojure because he wanted a modern Lisp for functional programming , symbiotic with the established Java platform, and designed for concurrency . He has also stressed the importance of simplicity in programming language design and software architecture, advocating for loose coupling , polymorphism via protocols and type classes instead of inheritance , stateless functions that are namespaced instead of methods or replacing syntax with data . Clojure's approach to state
1275-482: A number of other standard servlet classes available, for example for WebSocket communication. The Java servlet API has to some extent been superseded (but still used under the hood) by two standard Java technologies for web services: Typical implementations of these APIs on Application Servers or Servlet Containers use a standard servlet for handling all interactions with the HTTP requests and responses that delegate to
1360-440: A small portion of code to which Sun did not hold the copyright. Sun's vice-president Rich Green said that Sun's ideal role with regard to Java was as an evangelist . Following Oracle Corporation 's acquisition of Sun Microsystems in 2009–10, Oracle has described itself as the steward of Java technology with a relentless commitment to fostering a community of participation and transparency. This did not prevent Oracle from filing
1445-679: A very popular programming language since then. Java was the third most popular programming language in 2022 according to GitHub . Although still widely popular, there has been a gradual decline in use of Java in recent years with other languages using JVM gaining popularity. Java was originally developed by James Gosling at Sun Microsystems . It was released in May 1995 as a core component of Sun's Java platform . The original and reference implementation Java compilers , virtual machines, and class libraries were originally released by Sun under proprietary licenses . As of May 2007, in compliance with
1530-677: Is actually two compilers in one; and with GraalVM (included in e.g. Java 11, but removed as of Java 16) allowing tiered compilation . Java itself is platform-independent and is adapted to the particular platform it is to run on by a Java virtual machine (JVM), which translates the Java bytecode into the platform's machine language. Programs written in Java have a reputation for being slower and requiring more memory than those written in C++ . However, Java programs' execution speed improved significantly with
1615-441: Is characterized by the concept of identities, which are represented as a series of immutable states over time. Since states are immutable values, any number of workers can operate on them in parallel, and concurrency becomes a question of managing changes from one state to another. For this purpose, Clojure provides several mutable reference types , each having well-defined semantics for the transition between states. Clojure runs on
1700-482: Is entirely dynamic , recent efforts have also sought the implementation of a dependent type system . The language was created by Rich Hickey in the mid-2000s, originally for the Java platform; the language has since been ported to other platforms, such as the Common Language Runtime (.NET). Hickey continues to lead development of the language as its benevolent dictator for life . Rich Hickey
1785-435: Is forbidden. It is possible to force a capturing macro expansion, but it must be done explicitly. Clojure does not allow user-defined reader macros, but the reader supports a more constrained form of syntactic extension. Clojure supports multimethods and for interface -like abstractions has a protocol based polymorphism and data type system using records , providing high-performance and dynamic polymorphism designed to avoid
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#17327722569411870-409: Is implicitly allocated on the stack or explicitly allocated and deallocated from the heap . In the latter case, the responsibility of managing memory resides with the programmer. If the program does not deallocate an object, a memory leak occurs. If the program attempts to access or deallocate memory that has already been deallocated, the result is undefined and difficult to predict, and the program
1955-626: Is insufficient free memory on the heap to allocate a new object; this can cause a program to stall momentarily. Explicit memory management is not possible in Java. Java does not support C/C++ style pointer arithmetic , where object addresses can be arithmetically manipulated (e.g. by adding or subtracting an offset). This allows the garbage collector to relocate referenced objects and ensures type safety and security. As in C++ and some other object-oriented languages, variables of Java's primitive data types are either stored directly in fields (for objects) or on
2040-399: Is likely to become unstable or crash. This can be partially remedied by the use of smart pointers , but these add overhead and complexity. Garbage collection does not prevent logical memory leaks, i.e. those where the memory is still referenced but never used. Garbage collection may happen at any time. Ideally, it will occur when a program is idle. It is guaranteed to be triggered if there
2125-482: Is more likely that the compiler will use a parsing rule that allows all expressions of the form "LiteralOrIdentifier + LiteralOrIdentifier" and then the error will be detected during contextual analysis (when type checking occurs). In some cases this validation is not done by the compiler, and these errors are only detected at runtime. In a dynamically typed language, where type can only be determined at runtime, many type errors can only be detected at runtime. For example,
2210-478: Is necessary for complete syntactic analysis, and these are done together or concurrently . In a compiler , the syntactic analysis comprises the frontend , while the semantic analysis comprises the backend (and middle end, if this phase is distinguished). Computer language syntax is generally distinguished into three levels: Distinguishing in this way yields modularity, allowing each level to be described and processed separately and often independently. First,
2295-420: Is no longer needed, typically when objects that are no longer needed are stored in containers that are still in use. If methods for a non-existent object are called, a null pointer exception is thrown. One of the ideas behind Java's automatic memory management model is that programmers can be spared the burden of having to perform manual memory management. In some languages, memory for the creation of objects
2380-516: Is not intended to be code-compatible with other dialects of Lisp, since it uses its own set of data structures incompatible with other Lisps. Clojure advocates immutability and immutable data structures and encourages programmers to be explicit about managing identity and its states. This focus on programming with immutable values and explicit progression-of-time constructs is intended to facilitate developing more robust, especially concurrent , programs that are simple and fast. While its type system
2465-538: Is supported for interfaces . Java uses comments similar to those of C++. There are three different styles of comments: a single line style marked with two slashes ( // ), a multiple line style opened with /* and closed with */ , and the Javadoc commenting style opened with /** and closed with */ . The Javadoc style of commenting allows the user to run the Javadoc executable to create documentation for
2550-466: Is the creator of the Clojure language. Before Clojure, he developed dotLisp , a similar project based on the .NET platform, and three earlier attempts to provide interoperability between Lisp and Java : a Java foreign language interface for Common Lisp ( jfli ), A Foreign Object Interface for Lisp (FOIL), and a Lisp-friendly interface to Java Servlets (Lisplets). Hickey spent about two and
2635-451: Is the latest version (Java 22, and 20 are no longer maintained). Java 8, 11, 17, and 21 are previous LTS versions still officially supported. James Gosling , Mike Sheridan, and Patrick Naughton initiated the Java language project in June 1991. Java was originally designed for interactive television, but it was too advanced for the digital cable television industry at the time. The language
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2720-407: Is usually defined using a combination of regular expressions (for lexical structure) and Backus–Naur form (a metalanguage for grammatical structure) to inductively specify syntactic categories ( nonterminal ) and terminal symbols. Syntactic categories are defined by rules called productions , which specify the values that belong to a particular syntactic category. Terminal symbols are
2805-559: Is usually the case when compiling strongly-typed languages), though it is common to classify these kinds of error as semantic errors instead. As an example, the Python code contains a type error because it adds a string literal to an integer literal. Type errors of this kind can be detected at compile-time: They can be detected during parsing (phrase analysis) if the compiler uses separate rules that allow "integerLiteral + integerLiteral" but not "stringLiteral + integerLiteral", though it
2890-431: Is written inside classes, and every data item is an object, with the exception of the primitive data types, (i.e. integers, floating-point numbers, boolean values , and characters), which are not objects for performance reasons. Java reuses some popular aspects of C++ (such as the printf method). Unlike C++, Java does not support operator overloading or multiple inheritance for classes, though multiple inheritance
2975-421: The defmacro syntax also execute during parsing, meaning that a Lisp compiler must have an entire Lisp run-time system present. In contrast, C macros are merely string replacements, and do not require code execution. The syntax of a language describes the form of a valid program, but does not provide any information about the meaning of the program or the results of executing that program. The meaning given to
3060-616: The recur keyword. For parallel and concurrent programming Clojure provides software transactional memory , a reactive agent system , and channel -based concurrent programming. Clojure 1.7 introduced reader conditionals by allowing the embedding of Clojure, ClojureScript and ClojureCLR code in the same namespace. Transducers were added as a method for composing transformations. Transducers enable higher-order functions such as map and fold to generalize over any source of input data. While traditionally these functions operate on sequences , transducers allow them to work on channels and let
3145-593: The ConcurrentMaps and other multi-core collections, and it was improved further with Java 1.6. Some platforms offer direct hardware support for Java; there are micro controllers that can run Java bytecode in hardware instead of a software Java virtual machine, and some ARM -based processors could have hardware support for executing Java bytecode through their Jazelle option, though support has mostly been dropped in current implementations of ARM. Java uses an automatic garbage collector to manage memory in
3230-420: The Java platform and as a result, integrates with Java and fully supports calling Java code from Clojure, and Clojure code can be called from Java, too. The community uses tools such as Clojure command-line interface (CLI) or Leiningen for project automation, providing support for Maven integration. These tools handle project package management and dependencies and are configured using Clojure syntax. As
3315-508: The LR parser can parse any DCFL in linear time, the simple LALR parser and even simpler LL parser are more efficient, but can only parse grammars whose production rules are constrained. In principle, contextual structure can be described by a context-sensitive grammar , and automatically analyzed by means such as attribute grammars , though, in general, this step is done manually, via name resolution rules and type checking , and implemented via
3400-464: The expression problem . Clojure has support for lazy sequences and encourages the principle of immutability and persistent data structures . As a functional language , emphasis is placed on recursion and higher-order functions instead of side-effect-based looping. Automatic tail call optimization is not supported as the JVM does not support it natively; it is possible to do so explicitly by using
3485-418: The object lifecycle . The programmer determines when objects are created, and the Java runtime is responsible for recovering the memory once objects are no longer in use. Once no references to an object remain, the unreachable memory becomes eligible to be freed automatically by the garbage collector. Something similar to a memory leak may still occur if a programmer's code holds a reference to an object that
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3570-514: The parse tree , or "concrete syntax tree", which is determined by the grammar, but is generally far too detailed for practical use, and the abstract syntax tree (AST), which simplifies this into a usable form. The AST and contextual analysis steps can be considered a form of semantic analysis, as they are adding meaning and interpretation to the syntax, or alternatively as informal, manual implementations of syntactical rules that would be difficult or awkward to describe or implement formally. Thirdly,
3655-516: The stack (for methods) rather than on the heap, as is commonly true for non-primitive data types (but see escape analysis ). This was a conscious decision by Java's designers for performance reasons. Java contains multiple types of garbage collectors. Since Java 9, HotSpot uses the Garbage First Garbage Collector (G1GC) as the default. However, there are also several other garbage collectors that can be used to manage
3740-413: The 2023 edition of Stack Overflow Developer Survey, Clojure was the fourth most admired in the category of programming and scripting languages, with 68.51% of the respondents who have worked with it last year saying they would like to continue using it. In the desired category, however it was marked as such by only 2.2% of the surveyed, whereas the highest scoring JavaScript was desired by 40.15% of
3825-813: The Clojure JIRA project page. Anyone can ask questions or submit issues and ideas at ask.clojure.org. If it's determined that a new issue warrants a JIRA ticket, a core team member will triage it and add it. JIRA issues are processed by a team of screeners and finally approved by Rich Hickey. With continued interest in functional programming, Clojure's adoption by software developers using the Java platform has continued to increase. The language has also been recommended by software developers such as Brian Goetz, Eric Evans, James Gosling , Paul Graham , and Robert C. Martin . ThoughtWorks , while assessing functional programming languages for their Technology Radar, described Clojure as "a simple, elegant implementation of Lisp on
3910-600: The JVM" in 2010 and promoted its status to "ADOPT" in 2012. In the "JVM Ecosystem Report 2018" (which was claimed to be "the largest survey ever of Java developers"), that was prepared in collaboration by Snyk and Java Magazine, ranked Clojure as the 2nd most used programming language on the JVM for "main applications". Clojure is used in industry by firms such as Apple , Atlassian , Funding Circle , Netflix , Nubank , Puppet , and Walmart as well as government agencies such as NASA . It has also been used for creative computing, including visual art, music, games, and poetry. In
3995-834: The Java language, as part of J2SE 5.0. Prior to the introduction of generics, each variable declaration had to be of a specific type. For container classes, for example, this is a problem because there is no easy way to create a container that accepts only specific types of objects. Either the container operates on all subtypes of a class or interface, usually Object , or a different container class has to be created for each contained class. Generics allow compile-time type checking without having to create many container classes, each containing almost identical code. In addition to enabling more efficient code, certain runtime exceptions are prevented from occurring, by issuing compile-time errors. If Java prevented all runtime type errors ( ClassCastException s) from occurring, it would be type safe . In 2016,
4080-950: The Java language: As of November 2024 , Java 8, 11, 17, and 21 are supported as long-term support (LTS) versions, with Java 25, releasing in September 2025, as the next scheduled LTS version. Oracle released the last zero-cost public update for the legacy version Java 8 LTS in January 2019 for commercial use, although it will otherwise still support Java 8 with public updates for personal use indefinitely. Other vendors such as Adoptium continue to offer free builds of OpenJDK's long-term support (LTS) versions. These builds may include additional security patches and bug fixes. Major release versions of Java, along with their release dates: Sun has defined and supports four editions of Java targeting different application environments and segmented many of its APIs so that they belong to one of
4165-440: The Java platform must run similarly on any combination of hardware and operating system with adequate run time support. This is achieved by compiling the Java language code to an intermediate representation called Java bytecode , instead of directly to architecture-specific machine code . Java bytecode instructions are analogous to machine code, but they are intended to be executed by a virtual machine (VM) written specifically for
4250-523: The Python code is syntactically valid at the phrase level, but the correctness of the types of a and b can only be determined at runtime, as variables do not have types in Python, only values do. Whereas there is disagreement about whether a type error detected by the compiler should be called a syntax error (rather than a static semantic error), type errors which can only be detected at program execution time are always regarded as semantic rather than syntax errors. The syntax of textual programming languages
4335-635: The ability to run Java applets within web pages, and Java quickly became popular. The Java 1.0 compiler was re-written in Java by Arthur van Hoff to comply strictly with the Java 1.0 language specification. With the advent of Java 2 (released initially as J2SE 1.2 in December 1998 – 1999), new versions had multiple configurations built for different types of platforms. J2EE included technologies and APIs for enterprise applications typically run in server environments, while J2ME featured APIs optimized for mobile applications. The desktop version
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#17327722569414420-423: The concrete characters or strings of characters (for example keywords such as define , if , let , or void ) from which syntactically valid programs are constructed. Syntax can be divided into context-free syntax and context-sensitive syntax. Context-free syntax are rules directed by the metalanguage of the programming language. These would not be constrained by the context surrounding or referring that part of
4505-479: The contextual analysis resolves names and checks types. This modularity is sometimes possible, but in many real-world languages an earlier step depends on a later step – for example, the lexer hack in C is because tokenization depends on context. Even in these cases, syntactical analysis is often seen as approximating this ideal model. The levels generally correspond to levels in the Chomsky hierarchy . Words are in
4590-420: The developers participating in the survey. Syntax (programming languages) In computer science , the syntax of a computer language is the rules that define the combinations of symbols that are considered to be correctly structured statements or expressions in that language. This applies both to programming languages , where the document represents source code , and to markup languages , where
4675-410: The document represents data. The syntax of a language defines its surface form. Text-based computer languages are based on sequences of characters , while visual programming languages are based on the spatial layout and connections between symbols (which may be textual or graphical). Documents that are syntactically invalid are said to have a syntax error . When designing the syntax of a language,
4760-510: The first error – all it knows is that, after producing the token LEFT_PAREN, '(' the remainder of the program is invalid, since no word rule begins with '_'. The second error is detected at the parsing stage: The parser has identified the "list" production rule due to the '(' token (as the only match), and thus can give an error message; in general it may be ambiguous . Type errors and undeclared variable errors are sometimes considered to be syntax errors when they are detected at compile-time (which
4845-423: The following: Here the decimal digits, upper- and lower-case characters, and parentheses are terminal symbols. The following are examples of well-formed token sequences in this grammar: ' 12345 ', ' () ', ' (A B C232 (1)) ' The grammar needed to specify a programming language can be classified by its position in the Chomsky hierarchy . The phrase grammar of most programming languages can be specified using
4930-586: The generated servlet creates the response. Swing is a graphical user interface library for the Java SE platform. It is possible to specify a different look and feel through the pluggable look and feel system of Swing. Clones of Windows , GTK+ , and Motif are supplied by Sun. Apple also provides an Aqua look and feel for macOS . Where prior implementations of these looks and feels may have been considered lacking, Swing in Java SE 6 addresses this problem by using more native GUI widget drawing routines of
5015-404: The grammar to be changed more easily. Parsers are often written in functional languages, such as Haskell , or in scripting languages, such as Python or Perl , or in C or C++ . As an example, (add 1 1) is a syntactically valid Lisp program (assuming the 'add' function exists, else name resolution fails), adding 1 and 1. However, the following are invalid: The lexer is unable to identify
5100-596: The heap, such as the Z Garbage Collector (ZGC) introduced in Java 11, and Shenandoah GC, introduced in Java 12 but unavailable in Oracle-produced OpenJDK builds. Shenandoah is instead available in third-party builds of OpenJDK, such as Eclipse Temurin . For most applications in Java, G1GC is sufficient. In prior versions of Java, such as Java 8, the Parallel Garbage Collector was used as the default garbage collector. Having solved
5185-658: The host hardware. End-users commonly use a Java Runtime Environment (JRE) installed on their device for standalone Java applications or a web browser for Java applets . Standard libraries provide a generic way to access host-specific features such as graphics, threading , and networking . The use of universal bytecode makes porting simple. However, the overhead of interpreting bytecode into machine instructions made interpreted programs almost always run more slowly than native executables . Just-in-time (JIT) compilers that compile byte-codes to machine code during runtime were introduced from an early stage. Java's Hotspot compiler
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#17327722569415270-556: The implementation of floating-point arithmetic, and a history of security vulnerabilities in the primary Java VM implementation HotSpot . Developers have criticized the complexity and verbosity of the Java Persistence API (JPA), a standard part of Java EE. This has led to increased adoption of higher-level abstractions like Spring Data JPA, which aims to simplify database operations and reduce boilerplate code. The growing popularity of such frameworks suggests limitations in
5355-537: The introduction of just-in-time compilation in 1997/1998 for Java 1.1 , the addition of language features supporting better code analysis (such as inner classes, the StringBuilder class, optional assertions, etc.), and optimizations in the Java virtual machine, such as HotSpot becoming Sun's default JVM in 2000. With Java 1.5, the performance was improved with the addition of the java.util.concurrent package, including lock-free implementations of
5440-455: The memory management problem does not relieve the programmer of the burden of handling properly other kinds of resources, like network or database connections, file handles, etc., especially in the presence of exceptions. The syntax of Java is largely influenced by C++ and C . Unlike C++, which combines the syntax for structured, generic, and object-oriented programming, Java was built almost exclusively as an object-oriented language. All code
5525-522: The need to recompile. Java applications are typically compiled to bytecode that can run on any Java virtual machine (JVM) regardless of the underlying computer architecture . The syntax of Java is similar to C and C++ , but has fewer low-level facilities than either of them. The Java runtime provides dynamic capabilities (such as reflection and runtime code modification) that are typically not available in traditional compiled languages. Java gained popularity shortly after its release, and has been
5610-494: The others avoids relying on either convention or context to convey elements not included in the base set. The primary platform of Clojure is Java , but other target implementations exist. The most notable of these is ClojureScript, which compiles to ECMAScript 3, and ClojureCLR, a full port on the .NET platform, interoperable with its ecosystem. Other implementations of Clojure on different platforms include: Tooling for Clojure development has seen significant improvement over
5695-450: The parsing phase. Furthermore, these languages have constructs that allow the programmer to alter the behavior of the parser. This combination effectively blurs the distinction between parsing and execution, and makes syntax analysis an undecidable problem in these languages, meaning that the parsing phase may not finish. For example, in Perl it is possible to execute code during parsing using
5780-496: The platforms. The platforms are: The classes in the Java APIs are organized into separate groups called packages . Each package contains a set of related interfaces , classes, subpackages and exceptions . Sun also provided an edition called Personal Java that has been superseded by later, standards-based Java ME configuration-profile pairings. One design goal of Java is portability , which means that programs written for
5865-451: The program and can be read by some integrated development environments (IDEs) such as Eclipse to allow developers to access documentation within the IDE. The following is a simple example of a "Hello, World!" program that writes a message to the standard output : Java applets are programs embedded in other applications, mainly in web pages displayed in web browsers. The Java applet API
5950-527: The selling of licenses for specialized products such as the Java Enterprise System. On November 13, 2006, Sun released much of its Java virtual machine (JVM) as free and open-source software (FOSS), under the terms of the GPL-2.0-only license. On May 8, 2007, Sun finished the process, making all of its JVM's core code available under free software /open-source distribution terms, aside from
6035-650: The sentence may be false: The following C language fragment is syntactically correct, but performs an operation that is not semantically defined (because p is a null pointer , the operations p -> real and p -> im have no meaning): As a simpler example, is syntactically valid, but not semantically defined, as it uses an uninitialized variable . Even though compilers for some programming languages (e.g., Java and C#) would detect uninitialized variable errors of this kind, they should be regarded as semantic errors rather than syntax errors. To quickly compare syntax of various programming languages, take
6120-403: The soundness of the implementation) result in an error on translation or execution. In some cases, such programs may exhibit undefined behavior . Even when a program is well-defined within a language, it may still have a meaning that is not intended by the person who wrote it. Using natural language as an example, it may not be possible to assign a meaning to a grammatically correct sentence or
6205-555: The specifications of the Java Community Process , Sun had relicensed most of its Java technologies under the GPL-2.0-only license. Oracle offers its own HotSpot Java Virtual Machine, however the official reference implementation is the OpenJDK JVM which is free open-source software and used by most developers and is the default JVM for almost all Linux distributions. As of September 2024 , Java 23
6290-468: The standard JPA implementation's ease-of-use for modern Java development. The Java Class Library is the standard library , developed to support application development in Java. It is controlled by Oracle in cooperation with others through the Java Community Process program. Companies or individuals participating in this process can influence the design and development of the APIs. This process has been
6375-515: The syntax, whereas context-sensitive syntax would. A language can have different equivalent grammars, such as equivalent regular expressions (at the lexical levels), or different phrase rules which generate the same language. Using a broader category of grammars, such as LR grammars, can allow shorter or simpler grammars compared with more restricted categories, such as LL grammar, which may require longer grammars with more rules. Different but equivalent phrase grammars yield different parse trees, though
6460-409: The type system of Java was proven unsound in that it is possible to use generics to construct classes and methods that allow assignment of an instance one class to a variable of another unrelated class. Such code is accepted by the compiler, but fails at run time with a class cast exception. Criticisms directed at Java include the implementation of generics, speed, the handling of unsigned numbers,
6545-401: The underlying language (set of valid documents) is the same. Below is a simple grammar, defined using the notation of regular expressions and Extended Backus–Naur form . It describes the syntax of S-expressions , a data syntax of the programming language Lisp , which defines productions for the syntactic categories expression , atom , number , symbol , and list : This grammar specifies
6630-571: The underlying platforms. 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 is intended to replace Swing as the standard GUI library for Java SE , but since JDK 11 JavaFX has not been in the core JDK and instead in a separate module. JavaFX has support for desktop computers and web browsers on Microsoft Windows , Linux , and macOS . JavaFX does not have support for native OS look and feels. In 2004, generics were added to
6715-429: The use of tags , which consist of the character # followed by a symbol. When encountering a tag, the reader passes the value of the next element to the corresponding handler, which returns a data value. For example, this could be a tagged element: #myapp/Person {:first "Fred" :last "Mertz"} , whose interpretation will depend on the appropriate handler of the reader. This definition of extension elements in terms of
6800-494: The user define their own models for transduction. Extensible Data Notation , or edn , is a subset of the Clojure language intended as a data transfer format. It can be used to serialize and deserialize Clojure data structures, and Clojure itself uses a superset of edn to represent programs. edn is used in a similar way to JSON or XML , but has a relatively large list of built-in elements, shown here with examples: In addition to those elements, it supports extensibility through
6885-417: The web service methods for the actual business logic. JavaServer Pages ( JSP ) are server-side Java EE components that generate responses, typically HTML pages, to HTTP requests from clients . JSPs embed Java code in an HTML page by using the special delimiters <% and %> . A JSP is compiled to a Java servlet , a Java application in its own right, the first time it is accessed. After that,
6970-492: The years. The following is a list of some popular IDEs and text editors with plug-ins that add support for programming in Clojure: In addition to the tools provided by the community, the official Clojure command-line interface (CLI) tools have also become available on Linux , macOS , and Windows since Clojure 1.9. The development process is restricted to the Clojure core team, though issues are publicly visible at
7055-440: Was deprecated with the release of Java 9 in 2017. Java servlet technology provides Web developers with a simple, consistent mechanism for extending the functionality of a Web server and for accessing existing business systems. Servlets are server-side Java EE components that generate responses to requests from clients . Most of the time, this means generating HTML pages in response to HTTP requests, although there are
7140-665: Was initially called Oak after an oak tree that stood outside Gosling's office. Later the project went by the name Green and was finally renamed Java , from Java coffee , a type of coffee from Indonesia . Gosling designed Java with a C / C++ -style syntax that system and application programmers would find familiar. Sun Microsystems released the first public implementation as Java 1.0 in 1996. It promised write once, run anywhere (WORA) functionality, providing no-cost run-times on popular platforms . Fairly secure and featuring configurable security, it allowed network- and file-access restrictions. Major web browsers soon incorporated
7225-689: Was renamed J2SE. In 2006, for marketing purposes, Sun renamed new J2 versions as Java EE , Java ME , and Java SE , respectively. In 1997, Sun Microsystems approached the ISO/IEC JTC 1 standards body and later the Ecma International to formalize Java, but it soon withdrew from the process. Java remains a de facto standard , controlled through the Java Community Process . At one time, Sun made most of its Java implementations available without charge, despite their proprietary software status. Sun generated revenue from Java through
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