This chapter introduces Oolong, an assembly language for the Java virtual machine. The JVM uses a binary format called class files for communicating programs. Because it is difficult to edit and visualize class files, the Oolong language was created. It is nearly equivalent to the class file format but easier to read and write. The Oolong language takes care of certain bits-and-bytes-level details while allowing almost complete control of the class file.
To actually execute an Oolong program, it must be assembled into a class file. An Oolong assembler is provided with this book; Appendix B describes how to use it. It is a program called Oolong. This program is written in Java, so it should run on any JVM implementation you have.
You can edit Oolong source with any text editor. By convention, Oolong source file names end in .j.
This chapter provides a quick introduction to the overall structure of Oolong. The next chapters describe the details of writing methods, which are the executable parts of an Oolong class.