C++ :: Call Function With Arguments From Java

I am working on a project in a group at a university. We are creating a GUI in Java where the user can enter parameters. Then we want to be able to pass these parameters to a function inside our C/C++ program, that does the rest. How do I do this? So far I have managed to call a simple helloworld-function by using JNI, dll and a javah tool that create a header file from a java file. I define the helloworld-function in C and call it from Java.

Java file:

package helloworld;
public class HelloWorld {
private native void print();
public static void main(String[] args) {

[Code] ....

My problem is that I do not know how to call the helloworld-function with parameters. I guess that this is a special case when using JNI and a . dll. How do I pass simple char- and int-arguments from the Java class to the helloworld-C-function?