从LinkedList中删除元素（C＃）

Question

我正在尝试通过它的值从LinkedList中删除一个节点，但它似乎不起作用。 LinkedList类（带节点）：

public class Node<T>
    {
        private T info;
        private Node<T> next;

        public Node(T x, Node<T> next)
        {
            this.info = x;
            this.next = next;
        }

        public Node<T> GetNext()
        {
            return this.next;
        }

        public void SetNext(Node<T> next)
        {
            this.next = next;
        }

        public T GetInfo()
        {
            return this.info;
        }

        public void SetInfo(T x)
        {
            this.info = x;
        }

        public override string ToString()
        {
            return this.info.ToString();
        }
    }

    public class List<T>
    {

        private Node<T> first;

        public List()
        {
            this.first = null;
        }

        public Node<T> GetFirst()
        {
            return this.first;
        }

        public Node<T> Add(Node<T> pos, T x)
        {
            Node<T> temp = new Node<T>(x, null);

            if (pos == null)
            {
                temp.SetNext(this.first);
                this.first = temp;
            }
            else
            {
                temp.SetNext(pos.GetNext());
                pos.SetNext(temp);
            }

            return temp;
        }

        public Node<T> Remove(Node<T> pos)
        {
            if (this.first == pos)
                this.first = pos.GetNext();
            else
            {
                Node<T> prevPos = this.GetFirst();
                while (prevPos.GetNext() != pos)
                    prevPos = prevPos.GetNext();
                prevPos.SetNext(pos.GetNext());
            }

            Node<T> nextPos = pos.GetNext();
            pos.SetNext(null);

            return nextPos;
        }


        public override string ToString()
        {
            string str = "[";
            Node<T> pos = this.first;
            while (pos != null)
            {
                str += pos.GetInfo().ToString();
                if (pos.GetNext() != null)
                    str += ", ";
                pos = pos.GetNext();
            }

            str += "]";

            return str;
        }
    }

这就是功能：

public void Del(string info)
        {
            Node<T> previousNode = null, obsoleteNode = null, nextNode = null;
            Node<T> pos = this.first;
            while (pos != null)
            {
                if (pos == this.first && this.first.GetInfo().ToString() == info)
                {
                    Node<T> temp = pos;
                    this.first = this.first.GetNext();
                    temp = null;
                }
                else
                {
                    previousNode = pos;
                    if (previousNode != null)
                        obsoleteNode = previousNode.GetNext();
                    if (nextNode == null)
                        nextNode = pos.GetNext().GetNext();
                    if (obsoleteNode != null)
                    {
                        if (obsoleteNode.GetInfo().ToString() == info)
                            previousNode.SetNext(nextNode);
                    }
                }
                pos = pos.GetNext();
            }

        }

在VS autos中，它显示obsoleteNode实际上是null但我无法理解为什么。 所有其他值都没关系，除了pos之外，它会以某种方式获取列表中的最后一个节点而不是第一个节点，但是this.first本身是可以的。 可能是什么问题？