Harmony - Open Source Java SE

Apache Harmony is a modular Java runtime with class libraries and associated tools. One of the goals of the Harmony project is to create a design modular enough so that parts of the VM can be implemented in different languages. This project started in 2005 and it is under active development.

It adheres to the Java specification. It uses GNU classpath and JCVM a java byte code to C files converter. It has DRLVM, a virtual machine written in C++. It supports JIT compilation, JNI, Garbage Collector and Profile Collector etc.