Java compiler: Difference between revisions

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{{Short description|Program compiler for Java programming language}}

A '''Java compiler''' is a [[compiler]] for the [[Java (programming language)|Java programming language]].

A '''Java compiler''' is a [[compiler]] for the programming language [[Java (programming language)|Java]]. The most common form of output from a Java compiler is [[Java class file]]s containing platform-neutral [[Java bytecode]]<ref>{{Cite web|title=The Java Virtual Machine Specification, Java SE 8 Edition, Section 1.2|url=https://docs.oracle.com/javase/specs/jvms/se8/html/jvms-1.html#jvms-1.2|access-date=2021-09-24|language=en}}</ref>, but there are also compilers that output optimized [[Machine code|native machine code]] for a particular hardware/[[operating system]] combination, most notably the now discontinued [[GNU Compiler for Java]].<ref>{{Cite web|title=GCJ - past, present, and future|url=https://lwn.net/Articles/130796/|access-date=2021-09-24|language=en}}</ref>

Some Java compilers output optimized [[machine code]] for a particular hardware/[[operating system]] combination, called a ''[[Computing platform|___domain specific]]'' ''[[computer system]]''. An example would be the now discontinued [[GNU Compiler for Java]].<ref>{{Cite web|title=GCJ - past, present, and future|url=https://lwn.net/Articles/130796/|access-date=2021-09-24|language=en|archive-date=2019-08-02|archive-url=https://web.archive.org/web/20190802072307/https://lwn.net/Articles/130796/|url-status=live}}</ref>

Most Java-to-bytecode compilers do virtually no [[Optimization (computer science)|optimization]], leaving this until [[Run time (program lifecycle phase)|run time]] to be done by the [[Java virtual machine]] (JVM).{{Citation needed|date=September 2021}}

The most common form of output from a Java compiler is [[Java class file]]s containing [[cross-platform]] [[intermediate representation]] (IR), called [[Java bytecode]].<ref>{{Cite web|title=The Java Virtual Machine Specification, Java SE 8 Edition, Section 1.2|url=https://docs.oracle.com/javase/specs/jvms/se8/html/jvms-1.html#jvms-1.2|access-date=2021-09-24|language=en|archive-date=2021-09-24|archive-url=https://web.archive.org/web/20210924135604/https://docs.oracle.com/javase/specs/jvms/se8/html/jvms-1.html#jvms-1.2|url-status=live}}</ref>

The JVM loads the class files and either [[interpreter (computing)|interprets]] the [[bytecode]] or [[just-in-time compilation|just-in-time]] compiles it to [[machine code]] and then possibly optimizes it using [[dynamic compilation]].

The [[Java virtual machine]] (JVM) loads the class files and either [[interpreter (computing)|interprets]] the [[bytecode]] or [[just-in-time compilation|just-in-time]] compiles it to [[machine code]] and then possibly optimizes it using [[dynamic compilation]].

A standard on how to interact with Java compilers programmatically was specified in [[Java Specification Request|JSR]] 199.<ref>{{Cite web|url=https://jcp.org/en/jsr/detail?id=199|title=JSR 199: JavaTM Compiler API|access-date=2021-09-24}}</ref>

A standard on how to interact with Java compilers programmatically was specified in [[Java Specification Request|JSR]] 199.<ref>{{Cite web|url=https://jcp.org/en/jsr/detail?id=199|title=JSR 199: JavaTM Compiler API|access-date=2021-09-24|archive-date=2021-09-24|archive-url=https://web.archive.org/web/20210924135603/https://jcp.org/en/jsr/detail?id=199|url-status=live}}</ref>

== See also ==