此代碼是否通空到moveAfter（），以及如何處理它

Question

所以我得到這個代碼，據我所知，我不允許改變：

public void insertionSort() { 
    if (head == tail) { 
     // empty list is sorted 
     return; 
    } 
    Node nextNode = head.next; // start inserting second node 
    while (nextNode != tail) { 
     // set insertNode to node to be inserted in this iteration 
     Node insertNode = nextNode; 
     // set nextNode to node to be inserted in next iteration 
     nextNode = nextNode.next; 

     // find position where insertNode has to be inserted 
     Node current = insertNode.prev; 
     while (current != null && insertNode.value.compareTo(current.value) < 0) { 
      current = current.prev; 
     } 

     // insert insertNode after current 
     insertNode.moveAfter(current); 
    } 
} 

我不是很熟悉的鏈接名單但）我可以告訴如果第二while循環的第一次迭代工作那麼這個代碼將空進入moveAfter（到目前爲止的moveAfter（）我有：

/** 
    * Inserts this node after the specified node. If this and the specified node 
    * refer to the same node in the list, the list remains unchanged. If the 
    * specified node current is null, then this node is inserted at the head of 
    * the list. 
    * 
    * Precondition: this Node and the specified node are two nodes of this list 
    *    this node and the specified node are not equal to the tail 
    * 
    * @param node - the node in this list after which this node is inserted 
    */ 
    public void moveAfter (Node node) { 
     if(this.prev == null && node.next == null){ 
      throw new NoSuchElementException(); 
     } 
     if(node.prev == null && node.next==null){ 
      throw new NoSuchElementException(); 
     } 
     if(this == tail){ 
      throw new NoSuchElementException(); 
     } 
     if(node == tail){ 
      throw new NoSuchElementException(); 
     } 

      this.prev.next = this.next; 
      this.next = node.next; 
      node.next = this;        
      this.prev = node; 
    } 
} 

如果我是正確的，插入排序（ ）通過null moveAfter（）我怎麼能糾正這一點，並重置「當前」爲它原來的價值，如果我不能查nge insertionSort（）;

*旁註：道歉，如果我的問題很難閱讀或沒有正確地問。我似乎有一個竅門在這個網站上搞砸了他們。

Answer 1

您moveAfter()方法狀態之前的評論：

如果指定的節點電流爲null，則此節點插在列表的頭部。

由於insertionSort()使用head變量，我想這是一個成員變量，您也可以在moveAfter()用做作爲規範的狀態。