Swig typemap java object

Question

I am trying to generate java bindings through swig for these two c++ functions

C++ functions

void SetUserData(void* data);
void* GetUserData() const;
         


        

Answer 1

For completeness, here's another (simpler?) way to do it with JavaCPP. Assuming we have a GlobalData.h file like this in C++:

class Data {
public:
    JNIEnv* env;
    jobject data;

    Data(JNIEnv* env, jobject obj) : env(env), data(NULL) { }
    ~Data() { if (data != NULL) env->DeleteGlobalRef(data); }

    void SetUserData(jobject obj) { 
        if (data != NULL) env->DeleteGlobalRef(data);
        data = env->NewGlobalRef(obj);
    }
    jobject GetUserData() { return data; }
};

We can use it from Java this way:

import org.bytedeco.javacpp.*;
import org.bytedeco.javacpp.annotation.*;

@Platform(include="GlobalData.h")
public class GlobalData {
    static { Loader.load(); }

    public static class Data extends Pointer {
        public Data() { allocate(); }
        private native @Raw(withEnv=true) void allocate();

        public native void SetUserData(@Raw Object obj);
        public native @Raw Object GetUserData();
    }

    public static void main(String[] args) {
        Object someObject = new Object();
        Data myData = new Data();
        myData.SetUserData(someObject);
        Object sameObject = myData.GetUserData();

        System.out.println(someObject);
        System.out.println(sameObject);
    }
}

Where the output shows that someObject and sameObject point to the same object, for example:

java.lang.Object@7aa06577
java.lang.Object@7aa06577