class Peer {

        // used to hold the C++ object pointer
        private long peerobj;

        // create native object
        private native long create(int i);

        // destroy native object
        private native synchronized void destroy(long p);

        // get value of native object
        private native int getvalue(long p);

        // constructor - call create() to create native object
        public Peer(int i) {
            peerobj = create(i);
            System.out.println("create peerobj = " + peerobj);
        }

        // destroy native object if not already done
        public synchronized void destroy() {
            if (peerobj != 0) {
                System.out.println("destroy peerobj = " + peerobj);
                destroy(peerobj);
                peerobj = 0;
            }
        }

        // get value from native object
        public int getValue() {
            if (peerobj == 0) {
                throw new IllegalStateException(
                    "getValue called on destroyed object");
            }
            return getvalue(peerobj);
        }

        // destroy native object if it's still around
        // when finalize called from garbage collection
        public void finalize() {
            destroy();
        }
    }