See also
- Java compiler – for a general presentation of Java compilers, and a list of other existing alternative compilers.
- Java Platform
- OpenJDK
| Written in | Java [1] |
|---|---|
| Operating system | Cross-platform |
| Type | Compiler |
| License | GNU General Public License |
| Website | www |
javac (pronounced "java-see") is the primary Java compiler included in the Java Development Kit (JDK) from Oracle Corporation. Martin Odersky implemented the GJ compiler, and his implementation became the basis for javac. [2]
The compiler accepts source code conforming to the Java language specification (JLS) and produces Java bytecode conforming to the Java Virtual Machine Specification (JVMS).
javac is itself written in Java. The compiler can also be invoked programmatically. [3]
On 13 November 2006, Sun's HotSpot Java virtual machine (JVM) and Java Development Kit (JDK) were made available [4] under the GPL license. [5]
Since version 0.95, GNU Classpath, a free implementation of the Java Class Library, supports compiling and running javac using the Classpath runtime — GNU Interpreter for Java (GIJ) — and compiler — GNU Compiler for Java (GCJ) — and also allows one to compile the GNU Classpath class library, tools and examples with javac itself. [6]
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 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 that are typically not available in traditional compiled languages.
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 what is required in a JVM implementation. Having a specification ensures interoperability of Java programs across different implementations so that program authors using the Java Development Kit (JDK) need not worry about idiosyncrasies of the underlying hardware platform.
The GNU Compiler for Java (GCJ) is a discontinued free compiler for the Java programming language. It was part of the GNU Compiler Collection.
A GPL linking exception modifies the GNU General Public License (GPL) in a way that enables software projects which provide library code to be "linked to" the programs that use them, without applying the full terms of the GPL to the using program. Linking is the technical process of connecting code in a library to the using code, to produce a single executable file. It is performed either at compile time or run-time in order to produce functional machine-readable code. The Free Software Foundation states that, without applying the linking exception, a program linked to GPL library code may only be distributed under a GPL-compatible license. This has not been explicitly tested in court, but linking violations have resulted in settlement. The license of the GNU Classpath project explicitly includes a statement to that effect.
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 part of the GNU Project. It was originally developed in parallel with libgcj due to license incompatibilities, but later the two projects merged.
Kaffe is a discontinued "clean room design" version of a Java Virtual Machine. It comes with a subset of the Java Platform, Standard Edition, Java API, and tools needed to provide a Java runtime environment. Like most other Free Java virtual machines, Kaffe uses GNU Classpath as its class library.
Free Java implementations are software projects that implement Oracle's Java technologies and are distributed under free software licences, making them free software. Sun released most of its Java source code as free software in May 2007, so it can now almost be considered a free Java implementation. Java implementations include compilers, runtimes, class libraries, etc. Advocates of free and open source software refer to free or open source Java virtual machine software as free runtimes or free Java runtimes.
A Java compiler is a compiler for the Java programming language.
HotSpot, released as Java HotSpot Performance Engine, is a Java virtual machine for desktop and server computers, developed by Sun Microsystems and now maintained and distributed by Oracle Corporation. It features improved performance via methods such as just-in-time compilation and adaptive optimization. It is the de facto Java Virtual Machine, serving as the reference implementation of the Java programming language.
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. The Harmony project achieved 99% completeness for J2SE 5.0, and 97% for Java SE 6. The Android operating system has historically been a major user of Harmony, although since Android Nougat it increasingly relies on OpenJDK libraries.
JamVM is an open-source Java Virtual Machine (JVM) developed to be extremely small compared with other virtual machines (VMs) while conforming to the Java virtual machine specification version 2.
Jikes Research Virtual Machine is a mature virtual machine that runs programs written for the Java platform. Unlike most other Java virtual machines (JVMs), it is written in the programming language Java, in a style of implementation termed meta-circular. It is free and open source software released under an Eclipse Public License.
Java is a set of computer software and specifications that provides a software platform for developing application software and deploying it in a cross-platform computing environment. Java is used in a wide variety of computing platforms from embedded devices and mobile phones to enterprise servers and supercomputers. Java applets, 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 pages.
OpenJDK is a free and open-source implementation of the Java Platform, Standard Edition. It is the result of an effort Sun Microsystems began in 2006. The implementation is licensed under the GPL-2.0-only with a linking exception. Were it not for the GPL linking exception, components that linked to the Java Class Library would be subject to the terms of the GPL license. OpenJDK is the official reference implementation of Java SE since version 7.
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 of the platform-native libraries. Instead, the Java Platform provides a comprehensive set of standard class libraries, containing the functions common to modern operating systems.
IcedTea is a build and integration project for OpenJDK launched by Red Hat in June 2007. IcedTea also includes some addon libraries: IcedTea-Web is a free software implementation of Java Web Start and the Java web browser applet plugin. IcedTea-Sound is a collection of plugins for the Java sound subsystem, including the PulseAudio provider which used to be included with IcedTea. The Free Software Foundation recommends that all Java programmers use IcedTea as their development environment.
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 Application Programming Interface (API). It is derivative of the community driven OpenJDK which Oracle stewards. It provides software for working with Java applications. Examples of included software are the Java virtual machine, a compiler, performance monitoring tools, a debugger, and other utilities that Oracle considers useful for Java programmers.
Java bytecode is the instruction set of the Java virtual machine (JVM), crucial for executing programs written in the Java language and other JVM-compatible languages. Each bytecode operation in the JVM is represented by a single byte, hence the name "bytecode", making it a compact form of instruction. This intermediate form enables Java programs to be platform-independent, as they are compiled not to native machine code but to a universally executable format across different JVM implementations.
GraalVM is a Java Development Kit (JDK), written in Java. The open-source distribution of GraalVM is based on OpenJDK, and the enterprise distribution is based on Oracle JDK. As well as just-in-time (JIT) compilation, GraalVM can compile a Java application ahead-of-time so that it starts instantly, provides peak performance with no warmup, and uses fewer resources. It provides additional programming languages and execution modes. The first production-ready release, GraalVM 19.0, was distributed in May 2019. The most recent release is GraalVM for JDK 21, made available in September 2023.
[...]an application can access javac programmatically.