The GNU Compiler for Java (GCJ) is a discontinued free

compiler In computing, a compiler is a computer program that Translator (computing), translates computer code written in one programming language (the ''source'' language) into another language (the ''target'' language). The name "compiler" is primaril ...

for the

Java programming language Java is a high-level, general-purpose, memory-safe, object-oriented programming language. It is intended to let programmers ''write once, run anywhere'' ( WORA), meaning that compiled Java code can run on all platforms that support Jav ...

. It was part of the

GNU Compiler Collection The GNU Compiler Collection (GCC) is a collection of compilers from the GNU Project that support various programming languages, Computer architecture, hardware architectures, and operating systems. The Free Software Foundation (FSF) distributes ...

. GCJ compiles Java

source code In computing, source code, or simply code or source, is a plain text computer program written in a programming language. A programmer writes the human readable source code to control the behavior of a computer. Since a computer, at base, only ...

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 descr ...

(JVM)

bytecode 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 (normal ...

or to

machine code In computer programming, machine code is computer code consisting of machine language instructions, which are used to control a computer's central processing unit (CPU). For conventional binary computers, machine code is the binaryOn nonb ...

for a number of

CPU architecture In computer science and computer engineering, computer architecture is a description of the structure of a computer system made from component parts. It can sometimes be a high-level description that ignores details of the implementation. At a mo ...

s. It could also compile class files and whole JARs that contain bytecode into machine code.

History

The GCJ runtime-libraries original source is 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 ...

project, but there is a code difference between the libgcj libraries. GCJ 4.3 uses the

Eclipse An eclipse is an astronomical event which 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 ...

Compiler for Java as a front-end. In 2007, a lot of work was done to implement support for Java's two graphical

API An application programming interface (API) is a connection between computers or between computer programs. It is a type of software interface, offering a service to other pieces of software. A document or standard that describes how to build ...

s in

: AWT and Swing. Software support for AWT is still in development. "Once AWT support is working then Swing support can be considered. There is at least one free-software partial implementations of Swing that may be usable.". The GNU CLASSPATH was never completed to even Java 1.2 status and now appears to have been abandoned completely. As of 2015, there were no new developments announced from GCJ and the product was in

maintenance mode The meaning of maintenance mode depends on the context. In the world of software development, it refers to a point in a computer program's life when it has reached all of its goals and is generally considered to be "complete" and bug-free. The ...

, with open-source Java toolchain development mostly happening within

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, four years before the company was acquired by Oracle Corp ...

. GCJ was removed from the GCC trunk on September 30, 2016. Announcement of its removal was made with the release of the GCC 7.1, which does not contain it. GCJ remains part of GCC 6.

Performance

The compilation function in GCJ should have a faster start-up time than the equivalent bytecode launched in a JVM when compiling Java code into machine code.

Compiled Native Interface (CNI)

The Compiled Native Interface (CNI), previously named "Cygnus Native Interface", is a

software framework In computer programming, a software framework is a software abstraction that provides generic functionality which developers can extend with custom code to create applications. It establishes a standard foundation for building and deploying soft ...

for the GCJ that allows Java code to

call Call or Calls may refer to: Arts, entertainment, and media Games * Call (poker), a bet matching an opponent's * Call, in the game of contract bridge, a bid, pass, double, or redouble in the bidding stage Music and dance * Call (band), from L ...

, and be called by, native applications (programs specific to a hardware and operating-system platform) and libraries written in C++. CNI closely resembles the JNI (Java Native Interface) framework which comes as a standard with various

Comparison of language use

The authors of CNI claim for various advantages over JNI: CNI depends on Java classes appearing as C++ classes. For example,The example comes from: https://gcc.gnu.org/onlinedocs/gcj/Objects-and-Classes.html#Objects-and-Classes given a Java class, public class Int one can use the class thus: #include #include Int *mult(Int *p, int k)

References

External links

* * * * {{DEFAULTSORT:Gnu Compiler For Java Free and open source compilers

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