如何将c代码移植到java中？开始说明

I am working on porting a library over from C++ to Java. I want to know the first / initial steps to begin this port. I am not sure how will I test / debug? I could just start with the "main" file and begin rewriting code, but how and when do I test what I am doing? When I am done the COMPLETE port? How do I start about this, any help would be great.I am working on porting a library over from C++