What Java implementations, other than ports of the Sun JDK, are available for Linux?

Nathan Meyers

Kaffe is a cleanroom open-source implementation of the PersonalJava spec. It fully implements PersonalJava, implements most of the JDK1.1 spec, and implements a significant subset of the JDK1.2SE spec. It's available for Linux and many other platforms.

The GNU Compiler for Java (GCJ) is a native-language compiler for Java, and part of the GNU compiler suite. Together with the GNU Classpath project, GCJ provides a development and runtime environment for building native applications from Java source.

TowerJ is a commercial deployment environment for Java server-side applications. Using ahead-of-time compilation and a proprietary runtime engine, TowerJ boasts the best runtime performance available on an i386 platform.

Some other efforts, such as Japhar and ElectricalFire, do not appear to be under active development at the moment.