Does compilng java code to exe (e.g. using Launch4Java) ensure code cannot be reversed engineered?

Question

After experimenting myself, I am convinced that java code obsfucation is not safe in terms of preventing reverse code engineering. So, I turn to using Launch4J to bundle one of my core jar file into a single EXE file. The jar file contains the main entry method as well. Is this going to protect again code reverse engineering?

Answer 1

If a computer can run it, a human can reverse engineer it.

Answer 2

Launch4J doesn't translate your Java code into native executable code, it just provides a native launcher that looks for a JDK and has your JAR as a resource (either packaged inside the executable or not). This is just a convenience - not security. If your JAR is external to the executable, someone can reverse engineer your code like a regular Java application. If your JAR is packaged into the executable - Presumably, someone programmed the logic to wrap the JAR in the executable, and someone can program the logic to unwrap the JAR from the executable (or use one of many tools that can extract resources from executables) - and can then reverse engineer your code like a regular Java application.