Decompilers and Disassemblers
Articles, CafeBabe, Cavaj Java Decompiler, ClassCracker, ClassSpy, Decafe Pro, dis, Jad, JADO (Java Decompiler And Obfuscator), JCavaj, JODE (Java Optimize and Decompile Environment)
Interpreters
BeanShell, DynamicJava, FIJI: ForthIsh Java Interpreter, Lloyd's Java Shell (LJSH), Rhino - JavaScript for Java, Simkin, Tcl Java Integration
Lexer and Parser Generators
Beaver, BNF for Java, Coco/R for Java, Constructor of Useful Parsers (CUP), JavaCC, JELLRAP, JFlex, MixedCC - Mixed Compiler Compiler, Modern Compiler Implementation in Java, SableCC
Other To Java
C++ to Java Conversion Utility, C2J, Diamond Edge Applet Designer, Finite State Machines, JEX - Java Extension, LegacyJ PERCobol, XSLTC
Compiling the Java Programming Language
Issues related to compiling Java into native (object) code. Treats why, compiler architecture, links (Java compiling, compiling generally), frontend and infrastructure software.
Harissa
Java environment that includes a compiler from Java bytecode to C and a Java interpreter. [Open Source, GPL]
Java(tm) Bytecode Assembler
Free, but for research and educational use only.
Jikes
IBM Research Jikes Compiler Project. A Java compiler written in C++. [Open Source, IBM Public License]
Languages for the Java VM
A list of tools for programming to the Java virtual machine using a language other than Java itself. (Robert Tolksdorf)
The KOPI Project
Java compiler, byte-code assembler, disassembler. [Open Source, GPL]