How to integrate the reflection library into a Java Project

Regarding this Post: Can you find all classes in a package using reflection? In the answer section, someone said that loading all classes of a package can be done with the following reflection library: http://ift.tt/Ofz26b.

I downloaded and unzipped this library. But it only contains .java files and I do not know, how I can use the classes and the methods of this library. Normally, there is a .jar file which I can import... But in this folder there isn't!

So please can you tell me how I can import the library and make use of its classes and methods?

Thanks a lot

Alex