private ListItr(int index) {
			if (index < 0 || index > size) {
				throw new IndexOutOfBoundsException("Index: " + index + ", Size: " + size);
			}
			if (index < (size >> 1)) {
				next = head.next;
				for (nextIndex=0; nextIndex<index; nextIndex++) {
					next = next.next;
				}
			} else {
				next = tail;
				for (nextIndex=size-1; nextIndex>index; nextIndex--) {
					next = next.previous;
				}
			}
		}