weakref-snippet.java

        WeakHashMap<Integer, String> map = new WeakHashMap<Integer, String>();
        map.put(new Integer(10), "aaa"); // remove entry
//        map.put(10, "aaa"); // don't remove entry
//        map.put(Integer.valueOf(10), "aaa"); // don't remove entry

        for (int i = 0; i < Integer.MAX_VALUE; i++) {
            if (map.size() != 0) {
                System.out.println("At iteration " + i + " the map still holds the reference to object");
            } else {
                System.out.println("Object has finally been garbage collected at iteration " + i + ", the map is now empty");
                break;
            }
        }