Look for Java Native Interface (JNI). It's not too hard to get going, though it requires C/C++ code that was written for the purpose and won't usually talk to other C/C++ code. Here is a Sun Tutorial. Hope that helps!
A good question is never answered. It is not a bolt to be tightened into place but a seed to be planted and to bear more seed toward the hope of greening the landscape of the idea. John Ciardi