OpenJava - Extensible language based on Java. A Metaobject Protocol (MOP) is the extension interface; lets programmers customize language to implement new language features, mechanisms. PolyJ - Java with support for generic programming in the form of parameterized types. Provides constrained parametric polymorphism, with advantages over some other proposals for adding genericity to Java. [Open Source, GPL] JWIG - Java extensions for high-level Web service development; Java-based high-level language to develop interactive Web services; merges main features of <bigwig> language into Java by providing explicit support for Web service sessions, safe XHTML dynamic document building. MetaJ - A generic protocol-based self-applicative interpreter for Java. Revolves around a generic reification procedure which can be used to reify any class of the interpreter. Ptolemy II - Set of Java packages supporting heterogeneous, concurrent modeling and design. [Open Source, BDL] jContractor - Supports Design By Contract in Java. Discovers "contracts" during class loading and instruments the class bytecodes on-the-fly to check run-time contract violations. [Apache Open Source Licence] Borneo - Modification of the Java language designed to have true support for the IEEE 754 floating point standard. Pizza - A variant of Java that adds parametric polymorphism, first-class functions, and class cases and pattern matching to the language. The compiler compiles into Java byte code so the binaries can be run on a normal JVM. [Freeware] Jass - Java with assertions, spoken: jazz, like the music. Improvement of JaWA language extension. Gives Java the concepts of Design by Contract from Bertrand Meyer, and Eiffel, and extends them with new features. [Open Source, GPL] Bali - Java with a spoonful of syntactic sugar: proposed set of additions to make Java terser and safer. Terseness makes languages easier to read, write, maintain. Ideas from Abundance (Byte Magazine Oct 1986), Eiffel, Pascal, Delphi, Smalltalk, PL/I, Algol-68, Forth, even COBOL. Parameterized Types for Java - Technical paper reviewing PolyJ, an extension to Java allowing parameterized types. JavaParty - A minimal extension to Java easing distributed parallel programming of cluster computers. A source code transformation automatically generates a distributed pure Java program based on RMI or KaRMI. The Java Modeling Language (JML) - A behavioral interface specification language that can be used to specify the behavior of Java modules.