Question

I’m currently developing on a project written in Java. We have a bunch of algorithms written in C/C++ (at least a couple hundred) that need to be incorporated in our project. Our two options are to use JNI to call this code, or to rewrite all the algorithms in Java.

I am aware of the consequences of using JNI, it can open up a whole new set of problems, which is why rewriting all the code in Java is even being considered. But the thought of rewriting it seems…wrong. The algorithms have been tested and work as far as I know, they’re just in the wrong language.

In this situation, would JNI make this task easy? Or would it cause more headache than rewriting the code in Java would?

FYI – Our Java project is not meant to be portable in any way. That might eliminate one of the downsides of JNI in that it supposedly reduces portability.

Answer 1

The simple answer is, if the code is going to be called a lot AND performance matters then convert it over to Java.

The more complex answers are:

• if the library easily wrapped in JNI then go with JNI
• if the tests you have for the C/C++ code easily converted over to Java then go for the port

I would do the following:

• take one of the algorithms and wrap it in JNI
• take the same algorithm and convert it to Java
• see which is more of a pain to do
• if speed matters then profile both versions and see which of them is acceptable.