I'd like to know if it is possible to call an DLL coded in D from Java?
What you're looking for is JNI (Java Native Interface).If you export your D functions correctly, as you have done(extern(C) export) then you can call them the same way you would a C DLL.
This tutorial seems like it may have what you need: http://www.codeproject.com/Articles/2876/JNI-Basics Bit
