如何在Java中一次性查找Java中链表的中间元素

<b>import</b> test.LinkedList.Node;

<font><i>/**
 * Java program to find middle element of linked list in one pass.
 * In order to find middle element of linked list we need to find length first
 * but since we can only traverse linked list one time, we will use two pointers
 * one which we will increment on each iteration while other which will be
 * incremented every second iteration. so when first pointer will point to the
 * end of linked list, second will be pointing to the middle element of linked list
 * @author
 */</i></font><font>
<b>public</b> <b>class</b> LinkedListTest {
  
  
    <b>public</b> <b>static</b> <b>void</b> main(String args[]) {
        </font><font><i>//creating LinkedList with 5 elements including head</i></font><font>
      LinkedList linkedList = <b>new</b> LinkedList();
      LinkedList.Node head = linkedList.head();
      linkedList.add( <b>new</b> LinkedList.Node(</font><font>"1"</font><font>));
      linkedList.add( <b>new</b> LinkedList.Node(</font><font>"2"</font><font>));
      linkedList.add( <b>new</b> LinkedList.Node(</font><font>"3"</font><font>));
      linkedList.add( <b>new</b> LinkedList.Node(</font><font>"4"</font><font>));
    
      </font><font><i>//finding middle element of LinkedList in single pass</i></font><font>
      LinkedList.Node current = head;
      <b>int</b> length = 0;
      LinkedList.Node middle = head;
    
      <b>while</b>(current.next() != <b>null</b>){
          length++;
          <b>if</b>(length%2 ==0){
              middle = middle.next();
          }
          current = current.next();
      }
    
      <b>if</b>(length%2 == 1){
          middle = middle.next();
      }

      System.out.println(</font><font>"length of LinkedList: "</font><font> + length);
      System.out.println(</font><font>"middle element of LinkedList : "</font><font> + middle);
      
    } 
  
}

<b>class</b> LinkedList{
    <b>private</b> Node head;
    <b>private</b> Node tail;
  
    <b>public</b> LinkedList(){
        <b>this</b>.head = <b>new</b> Node(</font><font>"head"</font><font>);
        tail = head;
    }
  
    <b>public</b> Node head(){
        <b>return</b> head;
    }
  
    <b>public</b> <b>void</b> add(Node node){
        tail.next = node;
        tail = node;
    }
  
    <b>public</b> <b>static</b> <b>class</b> Node{
        <b>private</b> Node next;
        <b>private</b> String data;

        <b>public</b> Node(String data){
            <b>this</b>.data = data;
        }
      
        <b>public</b> String data() {
            <b>return</b> data;
        }

        <b>public</b> <b>void</b> setData(String data) {
            <b>this</b>.data = data;
        }

        <b>public</b> Node next() {
            <b>return</b> next;
        }

        <b>public</b> <b>void</b> setNext(Node next) {
            <b>this</b>.next = next;
        }
      
        <b>public</b> String toString(){
            <b>return</b> <b>this</b>.data;
        }
    }
}

Output:
length of LinkedList: 4
middle element of LinkedList : 2
</font>