LinkedNode

public class LinkedNode {
    private LinkedNode mPrev;
    private LinkedNode mNext;

    public LinkedNode() {
        mPrev = mNext = this;
    }

    public void insert(LinkedNode node) {
        node.mNext = mNext;
        mNext.mPrev = node;
        node.mPrev = this;
        mNext = node;
    }

    public void remove() {
        if (mNext == this) throw new IllegalStateException();
        mPrev.mNext = mNext;
        mNext.mPrev = mPrev;
        mPrev = mNext = null;
    }

    @SuppressWarnings("unchecked")
    public static class List<T extends LinkedNode> {
        private LinkedNode mHead = new LinkedNode();

        public void insertLast(T node) {
            mHead.mPrev.insert(node);
        }

        public T getFirst() {
            return (T) (mHead.mNext == mHead ? null : mHead.mNext);
        }

        public T getLast() {
            return (T) (mHead.mPrev == mHead ? null : mHead.mPrev);
        }

        public T nextOf(T node) {
            return (T) (node.mNext == mHead ? null : node.mNext);
        }

        public T previousOf(T node) {
            return (T) (node.mPrev == mHead ? null : node.mPrev);
        }

    }

    public static <T extends LinkedNode> List<T> newList() {
        return new List<T>();
    }
}