Welcome to OJ (f.a.k.a. OpenJava)

OJ (f.a.k.a. OpenJava) is an extensible language based on Java(TM). The OJ MOP (Metaobject Protocol) is the extension interface of the language. Through the MOP, the programmers can customize the language to implement a new language mechanism. OJ helps people who want to develop better Java libraries, that is, easy-to-use and efficient ones. It also helps people who are developing their own extended Java languages. OJ can also be regarded as a toolkit for constructing a Java preprocessor.

The special feature of the OJ MOP is its class metaobject API, through which programmers can handle source code as object oriented language constructs. i.e. classes, methods, fields, .. Though its translation is performed at compile-time, interfaces are similar to Java Reflection API at runtime and easy to use for high-level translations. For instance, getting information about methods, adding methods, modifying methods and so on are easier.

It is fully written in Java of JDK 1.1, so it can be run on any platform which supports Java Virtual Machine of JDK 1.1 and Java2. And, the generated codes are written in regular Java language, so the user's products can be run on any platform which supports regular JVM.

• Name OpenJava has been changed to OJ according to the request by Sun Microsystems. (Oct 15, 2007)
• Now metaclasses can be bound to member (inner) classes. Caller-side syntax extension (type suffix) does not work in some case for inner classes. Separated meta-binding configuration is enhanced to allow use of wild card "*" and "-" for specifying base classes. (Nov 17, 2001)

OJ 1.1 is available.

• Get packages suitable for you from Download Page
• A bit tips in installing and setting up are described at Setting-up Page (Last Modified on Aug 4, 2002 .)

• Browse online manual (HTML format)
• Browse tutorial (HTML format)

Additionally, if you need, OJ 0.2.x (old simple version) is still available from Download Page.

CVS server for the latest source code of OJ is available.
Try to login our CVS authentication server:

cvs -d:pserver:anonymous@cvs.openjava.sourceforge.net:/cvsroot/openjava login

cvs -z3 -d:pserver:anonymous@cvs.openjava.sourceforge.net:/cvsroot/openjava co OJ_1.1

mich@acm.org

• OpenJava: A Class-Based Macro System for Java
  Michiaki Tatsubori, Shigeru Chiba, Marc-Olivier Killijian and Kozo Itano
  Lecture Notes in Computer Science 1826, Reflection and Software Engineering, , Walter Cazzola, Robert J. Stroud, Francesco Tisato (Eds.), Springer-Verlag, pp.117-133, 2000. [PS]
• An Extension Mechanism for the Java Language
  Michiaki Tatsubori
  Master of Engineering Dissertation, Graduate School of Engineering, University of Tsukuba , University of Tsukuba, Ibaraki, Japan, Feb 2, 1999. [PS]
• Programming Support of Design Patterns with Compile-time Reflection
  Michiaki Tatsubori and Shigeru Chiba
  OOPSLA'98 Workshop on Reflective Programming in C++ and Java, pp.56-60, ISSN 1344-3135, Vancouver, Canada, Oct 18, 1998. [PS]
• Yet Another java.lang.Class
  Shigeru Chiba and Michiaki Tatsubori
  ECOOP'98 Workshop on Reflective Object-Oriented Programming and Systems, Brussels, Belgium, July 20, 1998.

• Now metaclasses can be bound to member (inner) classes. Caller-side syntax extension (type suffix) does not work in some case for inner classes. Separated meta-binding configuration is enhanced to allow use of wild card "*" and "-" for specifying base classes. (Build 20011117)
• Environment-conscious customized-suffixes are now enabled. A static method getDeclSuffix(Environment,String) can be declared in OJClass subclasses to make use of it. (Build 20010425)
• A bug of reporting NoSuchMemberException even for accessible innerclass's or outerclass's member is fixed. The class NullCompiler for people who want not to generate bytecode is added. (Build 20001010)
• A bug in parsing an array-typed member fields declaration is fixed. Declarations in a certain kind of syntax style was wrongly reconized. (Build 20000905)
• The class openjava.ptree.util.EvaluationShuttle is implemented completely. Some performance tuning of translation at caller-side. (Build 20000627)
• The bug of OJClass.isAssignableFrom() for array types is fixed. (Build 20000509)
• A bug in parsing some anonymous classes are fixed. A compiler option to turn off caller-side translation is added. (Build 20000124)
• OJClass.addClass(), OJConstructor.setExceptions() OJConstructor.addException() are added. A bug in SelfAccess.constantSuper() is fixed. (Build 19990626)
• The bug to fail to write a simple constructor is fixed. (Build 19990528).
• Some bugs are fixed. (Build 19990527)
• A few tutorials are added. (Build 19990525)
• Some exceptions thrown in the API are changed to be convenient. ojc.exe for Windows95/98/NT platform without ksh is included. (Build 19990520)
• Some comments for OJClass are partialy added. (Build 19990513)
• Some lacks in the API of OJClass are supplemented. (Build 199990508)
• Bugs in partial parser are fixed. (Build 199990507)
• Bugs around innerclasses are fixed. (Build 19990505)
• The first OJ 1.0 alpha is released. (Build 19990430)

We are developing other reflective systems for C++ and Java.

OpenC++

Javassist

Java