The extreme ease with which Java .class files can be reconstructed into Java sources that closely resemble the originals has a lot to do with Java byte-code design goals and trade-offs.

OpenJDK proposal would replace ASM with an up-to-date and performant API for parsing, generating, and transforming Java class files.

The ability to create class bytecode files. The ability to develop Java applets for browsers. The ability to create applications that will run in a Java Virtual Machine (JVM).