GNU Compiler for Java

The GCJ runtime-libraries original source is from GNU Classpath project, but there is a code difference between the libgcj libraries. GCJ 4.3 uses the Eclipse Compiler for Java as a front-end.

{{cite web | title = gcj to use Eclipse compiler as a front end | url = https://gcc.gnu.org/java/ | date = 2007-01-08 | access-date = 2007-05-20 | url-status = dead | archive-url = https://web.archive.org/web/20070509055923/http://gcc.gnu.org/java/ | archive-date = 2007-05-09 }}

In 2007, a lot of work was done to implement support for Java's two graphical APIs in GNU Classpath: 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.".[https://gcc.gnu.org/java/faq.html#2_4 The GCJ FAQ] 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, with open-source Java toolchain development mostly happening within OpenJDK.[https://www.phoronix.com/scan.php?page=news_item&px=MTUwOTA GCC Looks To Turn Off Java, Replace With Go Or ADA] GCJ was removed from the GCC trunk on September 30, 2016.{{cite web|url=https://gcc.gnu.org/viewcvs/gcc?view=revision&revision=240661|title=[gcc] Revision 240661|date=September 30, 2016|author=Andrew Haley}}{{Cite web|url=https://tromey.com/blog/?p=911|title=The Deletion of gcj|last=Tromey|first=Tom|date=October 2, 2016|website=The Cliffs of Inanity|access-date=October 3, 2016}} Announcement of its removal was made with the release of the GCC 7.1, which does not contain it.{{cite web|url=https://gcc.gnu.org/gcc-7/changes.html|title=GCC 7 Release Series: Changes, New Features, and Fixes|access-date=May 9, 2017}} GCJ remains part of GCC 6.

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.{{Cite web |url=http://www.hpl.hp.com/personal/Hans_Boehm/misc_slides/gcj2.pdf |title=GCJ: The GNU Static Java Compiler |access-date=2009-08-02 |archive-url=https://web.archive.org/web/20110607102558/http://www.hpl.hp.com/personal/Hans_Boehm/misc_slides/gcj2.pdf |archive-date=2011-06-07 |url-status=dead }}

The Compiled Native Interface (CNI), previously named "Cygnus Native Interface", is a software framework for the GCJ that allows Java code to call, 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 Java virtual machines.

The authors of CNI claim for various advantages over JNI:[https://gcc.gnu.org/java/faq.html#2_3 The GCJ FAQ – GNU Project – Free Software Foundation (FSF)]

{{cquote|We use CNI because we think it is a better solution, especially for a Java implementation that is based on the idea that Java is just another programming language that can be implemented using standard compilation techniques. Given that, and the idea that languages implemented using Gcc should be compatible where it makes sense, it follows that the Java calling convention should be as similar as practical to that used for other languages, especially C++, since we can think of Java as a subset of C++. CNI is just a set of helper functions and conventions built on the idea that C++ and Java have the *same* calling convention and object layout; they are binary compatible. (This is a simplification, but close enough.)

}}

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 {{Webarchive|url=https://web.archive.org/web/20161020222612/https://gcc.gnu.org/onlinedocs/gcj/Objects-and-Classes.html#Objects-and-Classes |date=2016-10-20 }}

given a Java class,

public class Int

{

public int i;

public Int(int i) { this.i = i; }

public static Int zero = new Int(0);

}

one can use the class thus:

1. include
2. include

Int *mult(Int *p, int k)

{

if (k == 0)

return Int::zero; // Static member access.

return new Int(p->i * k);

}

{{Portal|Free and open-source software|Computer programming}}

• Excelsior JET (Excelsior Java native code compiler)
• IcedTea
• Kaffe
• SableVM
• JamVM
• Apache Harmony
• Jikes
• GraalVM - GraalVM's Native Image functionality is an ahead-of-time compilation technology that produces executable binaries of class files.
• Java virtual machine
• Free Java implementations
• Kotlin - Kotlin/Native is a technology for compiling Kotlin to native binaries that run without any JVM. It comprises a LLVM-based backend for the Kotlin compiler and a native implementation of the Kotlin runtime library.

{{Reflist}}

• {{cite web |url= http://gcc.gnu.org/java/ |title= Official website |publisher= GNU |work= GCC |date= Mar 30, 2007 |url-status= dead |archive-date= May 9, 2007 |archive-url= https://web.archive.org/web/20070509055923/http://gcc.gnu.org/java/ }}
• {{cite web |url= http://gcc.gnu.org/onlinedocs/gcj/ |title= GCJ Manual |url-status= dead |archive-date= August 22, 2016 |archive-url= https://web.archive.org/web/20160822153028/http://gcc.gnu.org/onlinedocs/gcj/ }}
• {{cite web |url= http://gcc.gnu.org/onlinedocs/gcj/About-CNI.html |title= About CNI |work= GCJ Manual |url-status= dead |archive-date= July 28, 2016 |archive-url= https://web.archive.org/web/20160728215116/http://gcc.gnu.org/onlinedocs/gcj/About-CNI.html }}
• {{cite web |url= https://lwn.net/Articles/130796/ |publisher= LWN |title= GCJ - past, present, and future |first= Mark |last= Wielaard |date= Apr 6, 2005 |url-status= live |archive-date= August 2, 2019 |archive-url= https://web.archive.org/web/20190802072307/https://lwn.net/Articles/130796/ }}

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Category:Free and open source compilers

Java

Category:Java compilers

Category:Discontinued Java virtual machines