//In java public void addElement(Item item) { if (item == null) { throw new NullPointerException("Null item passed"); } else { Node oldFirst = first; Node newNode = new Node(); newNode.item = item; newNode.next = oldFirst; newNode.prev = null; first = newNode; if (first.next == null) { last = first; } else { oldFirst.prev = first; } oldFirst = null; //release the memory } }