I'm starting a project that will have to instrument java applications for coverage purposes (definition-usage of variables, etc). It has to add trace statements and some logic to the application and maybe remove statements.

I have searched for ways of instrument Java code and what I always find is about bytecode instrumentation.

My question is: It's the only way to instrument Java applications? There is any other way to do that? What are the advantages of bytecode instrumentation over the others?

I'll probably use the bytecode solution, but I want to know what are the problems with the other approaches (if any) to decide precisely.

Thanks!