Use a simple c++ class in Android NDK

Issue

I'm trying to learn the basics of Android NDK but I'm stucked when I have to use it with a c++ class.

I understand how to use it with a simple function but what should I do to be able to manipulate the fields and the methods of a c++ class ?

I'm trying to do it with this simple c++ class :

#include <cstdlib>
#include <jni.h>
using namespace std;


class Point {
   int x, y; // coordonnées du point

   public:
      Point() {
         this->x = 0;
         this->y = 0;
      }

      Point(int x, int y) {
         this->x = x;
         this->y = y;
      }

      int getX() const {
         return x;
      }

      int getY() const {
         return y;
      }

      Point symetrique() const {
         return Point(-x, -y);
      }

      bool operator ==(const Point &p) const {
         return this->x == p.getX() && this->y == p.getY();
      }
};

extern "C" {
    JNIEXPORT jlong JNICALL Java_com_example_jnipoint_JPoint_createPoint__
      (JNIEnv *, jobject);

    JNIEXPORT jlong JNICALL Java_com_example_jnipoint_JPoint_createPoint__II
      (JNIEnv *, jobject, jint, jint);

    JNIEXPORT jint JNICALL Java_com_example_jnipoint_JPoint_nativeGetX
      (JNIEnv *, jobject, jlong);

    JNIEXPORT jint JNICALL Java_com_example_jnipoint_JPoint_nativeGetY
      (JNIEnv *, jobject, jlong);

    JNIEXPORT jlong JNICALL Java_com_example_jnipoint_JPoint_nativeSymetrique
      (JNIEnv *, jobject, jlong);
};


JNIEXPORT jlong JNICALL Java_com_example_jnipoint_JPoint_createPoint__(JNIEnv* env, jobject thiz) {
    return (jlong)(new Point());
}

JNIEXPORT jlong JNICALL Java_com_example_jnipoint_JPoint_createPoint__II(JNIEnv* env, jobject thiz, jint x, jint y) {
    return (jlong)(new Point(x, y));
}

JNIEXPORT jint JNICALL Java_com_example_jnipoint_JPoint_nativeGetX(JNIEnv* env, jobject thiz, jlong nativePointer) {
    return ((Point*)nativePointer)->getX();
}

JNIEXPORT jint JNICALL Java_com_example_jnipoint_JPoint_nativeGetY(JNIEnv* env, jobject thiz, jlong nativePointer) {
    return ((Point*)nativePointer)->getY();
}

jlong Java_com_example_jnipoint_JPoint_nativeSymetrique(JNIEnv* env, jobject thiz, jlong nativePointer) {
    return ((Point*)nativePointer)->symetrique();
}

I tried to find samples but nothing so far... Maybe I'm not using the right keywords

* UPDATE *

I created a Java wrapper for the c++ Point class and added to the c++ file JNI methods. The code is the following :

public class JPoint {

    private long nativePointer;

    public JPoint() {
        nativePointer = createPoint();
    }

    public JPoint(int x, int y) {
        nativePointer = createPoint(x, y);
    }

    public int getX() {
        return nativeGetX(nativePointer);
    }

    public int getY() {
        return nativeGetY(nativePointer);
    }

    public JPoint symetrique() {
        JPoint tmp = new JPoint();
        tmp.nativePointer = nativeSymetrique(nativePointer);
        return tmp;
    }

    // TODO
    /*public boolean equals(Object o) {
        return nativeEquals(o);
    }*/

    private native long createPoint(); // Void constructor
    private native long createPoint(int x, int y);
    private native int nativeGetX(long nativePointer);
    private native int nativeGetY(long nativePointer);
    private native long nativeSymetrique(long nativePointer);
    //private native boolean nativeEquals(Object p); TODO
}

Right now I'm stucked with the nativeSymetrique function, it says that I cannot convert 'Point' to 'jlong'. Can anyone help me on this ? Thanks

* UPDATE 2 *

SWIG solved my issues, you don't have to handwrite the wrappers and it seems to be a good choice for big libraries.

Solution

As I said in my second update, SWIG was the perfect match for my needs.

Answered By - Fr4nz