A library to parse Java class files
This library started out as a test project, in order to read and understand the contents of Java class files — without having to rely on other people's work. As time passed, it became obvious that the functionality merited its own library, and this is it.
What differentiates this library from others —apart from the fact that writing class files is currently not under consideration— is that it is intended to present the bytecode that you need; for example, for a method invocation, or a lambda expression.
Also, it tries to take a functional approach as much as possible: not because FP would be somehow inherently superior, but because certain things just work so much better when using a functional style.