How to Call C++ Method from Java

Question

I need to call C++ method from Java.
I have gone through the JNI tuorial , but was not able to pin point things.
I read that :
You have to write JNI c functions which then call your C++ member functions.You need to write a JNI function which will call new on your C++ class.
Now i have java class :
Java Code JavaClass.java ---->
class JavaClass{
public native void nativeMethod();
    static
        System.loadLibrary("NativeCppCode");
     private void callCppMethod()
          //call C++ method
                JavaClass jvc = new JavaClass();
                jvc.nativeMethod()
}Cpp Code:
NativeCppCode.h---->
class NativeCppCode
public:
    getValue();
    setValue();
private:
   int a;
JNIEXPORT void JNICALL Java_JavaClass_nativeMethod(JNIEnv *env
               ,jobject obj);NativeCppCode.C---->
NativeCppCode::getValue()
   return a;
NativeCppCode::setValue()
   a = 1;
JNIEXPORT void JNICALL Java_JavaClass_nativeMethod(JNIEnv *env
               ,jobject obj)
NativeCppCode* nativeInstabce = new NativeCppCode();
NativeCppCode.setValue();
}Is this the correct way to do it.
Any suggestion would be a great help to me

Answer 1

tryit wrote:
I need to call C++ method from Java.Not possible.
JNI uses C methods.
Is this the correct way to do it.Same way you would do it in any C/C++ method (not java)
       MyClass* p = ....
       p->doit();
Common idiom for the pointer in the above is to pass it back and forth to your java code as a java long. You cast it it and from your class pointer. Provide an explicit java method to free it when done. Besides providing the explicit method also implement a finalizer to free it as well (however that is a fail safe and should not be relied upon.)