Java HotSpot Virtual Machine

Currently I have a working C app that calls a function in a java class whose .class file is in the same directory as the C executable. I would like to place the class file in another directory and still be able to run the C code. How is this done? I have tried setting the classpath environment variable and have also tried specifying the -Djava.class.path option in the JavaVMOption array. Neither method has been successful. Has anyone gotten this to work on a linux machine?

Thanks, Andreas