A question about JNI references, persistence, and garbage collection

Question

I am writing a library to allow our Java developers to access C functions in our product. I want people on the Java side to be able to instantiate instances of a new object (on the C side), say "Map", and I want those objects to persist until they are destroyed on the Java side. I am thinking of creating a wrapper for the native methods, which stores an identifier for the instance of an object. When the C object is accessed, the identifier is passed to the C code which looks up the correct object in a table. I understand that if I use the NewGlobalReference call in JNI I can get objects to persist.
When it is time for garbage collection I plan to override finalize() to call the C code and tell it to remove the Global Reference.
Here's what I have in mind
public class JMap() {
     private static int id;
     static {
          System.loadLibrary("libMap");
          /*Call C method which instantiates object and creates a GlobalReference
          which is stored in table. Returns ID for reference*/
          id = _init();
     public void setSize(int x, int y) {
          _setSize(id, x, y);
     public void finalize() {
          _finalize(id);
          super.finalize();
     private native int _init();
     /*calls DeleteGlobalReference for the reference matching this id*/
     private native void _finalize(int id);
     private native void _setSize(int id, int x, int y);
}Is this the right thing to do? Have I understood the way JNI works with regard to GlobalReferences?
Any comments, tips or pointers would be appreciated :)

Answer 1

This probably should have been posted in the Native Methods sub-forum, I have reposted there:
http://forum.java.sun.com/thread.jspa?threadID=657667
Mods please delete this post :)