Editing Coroutine (section)

===Java===
There are several implementations for coroutines in [[Java (programming language)|Java]].  Despite the constraints imposed by Java's abstractions, the JVM does not preclude the possibility.<ref name="jvmsummit">{{cite web|url=http://www.wiki.jvmlangsummit.com/images/2/2b/JVMLanguageSummit_Stadler_Continuations.pdf|author=Lukas Stadler|series=JVM Language Summit|title=JVM Continuations|year=2009|access-date=2011-10-03|archive-date=2012-04-23|archive-url=https://web.archive.org/web/20120423215434/http://wiki.jvmlangsummit.com/images/2/2b/JVMLanguageSummit_Stadler_Continuations.pdf|url-status=live}}</ref> There are four general methods used, but two break bytecode portability among standards-compliant JVMs.

* Modified JVMs. It is possible to build a patched JVM to support coroutines more natively. The [http://openjdk.java.net/projects/mlvm/ Da Vinci JVM] has had patches created.<ref name="javanet-forax">{{cite web|url=http://weblogs.java.net/blog/forax/archive/2009/11/19/holy-crap-jvm-has-coroutinecontinuationfiber-etc|author=Remi Forax|archive-url=https://web.archive.org/web/20150319052055/http://weblogs.java.net/blog/forax/archive/2009/11/19/holy-crap-jvm-has-coroutinecontinuationfiber-etc|archive-date=19 March 2015|title=Holy crap: JVM has coroutine/continuation/fiber etc.|date=19 November 2009}}</ref>
* Modified bytecode. Coroutine functionality is possible by rewriting regular Java bytecode, either on the fly or at compile time. Toolkits include [http://commons.apache.org/sandbox/commons-javaflow/ Javaflow], [http://code.google.com/p/coroutines/ Java Coroutines], and [https://github.com/offbynull/coroutines Coroutines].
* Platform-specific JNI mechanisms. These use JNI methods implemented in the OS or C libraries to provide the functionality to the JVM.{{citation needed|date=May 2014}}
* Thread abstractions. Coroutine libraries which are implemented using threads may be heavyweight, though performance will vary based on the JVM's thread implementation.