In the Reversing Java: Part I, I’ve described the main structure of Java class file bytes. In this part, I’ll continue decompiling the HelloWorld example.

Recently I’ve interested in byte code structure of Java and Dalvik. I’ve found some useful tools for playing with them.

Destination Byte Code

Java byte codes are simple to reverse engineering because they compile in run time. i.e. JVM will execute the byte codes in run time, thus Java code is cross platform but executes with more delay than direct compiled machine codes (for example using C++ and gcc).