从单向链表 (Java) 中删除最后一个节点

Question

我的方法int deletLast（）应该删除最后一个节点，并返回要删除的节点中的值。 我的代码似乎不起作用。 它不会删除最后一个节点。 任何帮助将不胜感激。

import java.util.NoSuchElementException;import java.util.Scanner;

公共类 LinkedList11 { 私有内部类节点

private class Node{
    int data;
    Node link;

    public Node(){
        data = Integer.MIN_VALUE;
        link = null;
    }
    public Node(int x, Node p){
        data = x;
        link = p;
    }
}
// End of Node class
public Node head;
public LinkedList11(){
    head = null;
}
public int deleteLast() throws NoSuchElementException {

    if ( head == null )   //handle when list is empty
    { throw new NoSuchElementException();}
     if(head.link == null)  //handle when head is the only node
     { return head.data;

        }
        Node position = head;
        Node temp = head;   //temp has to be initialized to something 
        int dataAtEnd =0;
        while (position != null)
        {   dataAtEnd = position.data;    
            temp =position;               //safe keep current position
           position = position.link;     //update position pointer to get the next value  
          }
       position =temp;  // store current position in next position
       return dataAtEnd;
}

}

Answer 1

首先，如果 head 是唯一的节点并且您想要删除它，则需要设置 head null。

if(head.link == null) {
    int result = head .data;
    head = null;
    return result;
}

在检查 head 是否是唯一节点后尝试这样的事情：

Node current = head;
while (current.link.link != null)
    current = current.link;
int result = current.link.data;
current.link = null;
return result;

Bc 您需要查看前面的步骤，以检查下一个节点是否是最后一个节点，并从最后一个节点之前的节点中删除最后一个节点。希望你明白，我的意思，对错别字表示歉意

Answer 2

删除行

"return head.data;"，该行位于您收到错误的位置正上方。"EAD = 空;给出错误" 给出无法访问，因为您在上面有一个返回语句，因此显然无法访问

'public int deleteLast（） 抛出 NoSuchElementException {

if ( head == null )   //handle when list is empty
{ throw new NoSuchElementException();}
 if(head.link == null)  //handle when head is the only node
 { 
     // You must store the data somewhere since head has to be set to NULL.
     int dataToReturn = head.data;
     // Since head is the only node, set it to NULL now.
     head = null;
     // Now return the data the the last node (head in this case) contained.
     return dataToReturn;
    }
    Node position = head;
    Node temp = head;   //temp has to be initialized to something 
    int dataAtEnd =0;
    while (position.link != null)
    {   dataAtEnd = position.data;    
        temp =position;               //safe keep current position
       position = position.link;     //update position pointer to get the next value  
      }
   position = null;
   temp.link = null;//this is what deletes the last node.
   return dataAtEnd;

}