Question

i have a native method with user defined datatypes(structure) as the parameters.How do i call this method from java using JNI?

Answer 1

If you have a method like this:

int cFunction(mydatatype data) ...

You cannot call it directly. You will need a layer of JNI to glue it together.

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So a JNI function is someting generated from your code:

class JavaTest {
    public native int jMethod(int a);
}

Running javah on that class you would get a header file like this:

JNIEXPORT jint JNICALL Java_Javatest_jMethod(JNIEnv*, jobject obj, jint a);

Implementing that method to call cFunction(mydatatype):

JNIEXPORT jint JNICALL Java_Javatest_jMethod(JNIEnv*, jobject obj, jint a) {
    mydatatype data;
    data.count = a;
    return (jint) cFunction(data);
}