循環チェーンテーブルのクラシック実装(JAVA)

public class LinkedListNode {//    

    public LinkedListNode previous;//    
    public LinkedListNode next;//    
    public Object object;//      

   
    public long timestamp;

 
    public LinkedListNode(Object object, LinkedListNode next, LinkedListNode previous)
    {
        this.object = object;
        this.next = next;
        this.previous = previous;
    }

   
    public void remove() {//    
        previous.next = next;
        next.previous = previous;
    }
   
 
    public String toString() {
        return object.toString();
    }
}

import java.util.*;


public class LinkedList {//    

    //   ，  ，        ，         
    private LinkedListNode head = new LinkedListNode("head", null, null);

  
    public LinkedList() {
        head.next = head.previous = head;
    }

   
    public LinkedListNode getFirst() {//            
        LinkedListNode node = head.next;
        if (node == head) {
            return null;
        }
        return node;
    }

   
    public LinkedListNode getLast() {//             
        LinkedListNode node = head.previous;
        if (node == head) {
            return null;
        }
        return node;
    }

   
    public LinkedListNode addFirst(LinkedListNode node) {//              ,     .
        node.next = head.next;
        node.previous = head;
        node.previous.next = node;
        node.next.previous = node;
        return node;
    }

   
    public LinkedListNode addFirst(Object object) {//             ,     .
        LinkedListNode node = new LinkedListNode(object, head.next, head);
        node.previous.next = node;
        node.next.previous = node;
        return node;
    }

    public LinkedListNode addLast(Object object) {//              ,     
        LinkedListNode node = new LinkedListNode(object, head, head.previous);
        node.previous.next = node;
        node.next.previous = node;
        return node;
    }

 
    public void clear() {//      
        //Remove all references in the list.
        LinkedListNode node = getLast();
        while (node != null) {
            node.remove();
            node = getLast();
        }

        //Re-initialize.
        head.next = head.previous = head;
    }

    public String toString() {
        LinkedListNode node = head.next;
        StringBuffer buf = new StringBuffer();
        while (node != head) {
            buf.append(node.toString()).append(", ");
            node = node.next;
        }
        return buf.toString();
    }
}

ソース: