/** * $RCSfile: LinkedListNode.java,v $ * $Revision: 1.1 $ * $Date: 2002/06/20 15:58:05 $ * * Copyright (C) 1999-2001 CoolServlets, Inc. All rights reserved. * * This software is the proprietary information of CoolServlets, Inc. * Use is subject to license terms. */package com.struts2.framework.util;/** * Doubly linked node in a LinkedList. Most LinkedList implementations keep the * equivalent of this class private. We make it public so that references * to each node in the list can be maintained externally. * * Exposing this class lets us make remove operations very fast. Remove is * built into this class and only requires two reference reassignments. If * remove existed in the main LinkedList class, a linear scan would have to * be performed to find the correct node to delete. * * The linked list implementation was specifically written for the Jive * cache system. While it can be used as a general purpose linked list, for * most applications, it is more suitable to use the linked list that is part * of the Java Collections package. * * @see com.imb.util.LinkedList */public class LinkedListNode {    public LinkedListNode previous;    public LinkedListNode next;    public Object object;    /**     * This class is further customized for the CoolServlets cache system. It     * maintains a timestamp of when a Cacheable object was first added to     * cache. Timestamps are stored as long values and represent the number     * of milleseconds passed since January 1, 1970 00:00:00.000 GMT.<p>     *     * The creation timestamp is used in the case that the cache has a     * maximum lifetime set. In that case, when     * [current time] - [creation time] > [max lifetime], the object will be     * deleted from cache.     */    public long timestamp;    /**     * Constructs a new linked list node.     *     * @param object the Object that the node represents.     * @param next a reference to the next LinkedListNode in the list.     * @param previous a reference to the previous LinkedListNode in the list.     */    public LinkedListNode(Object object, LinkedListNode next,            LinkedListNode previous)    {        this.object = object;        this.next = next;        this.previous = previous;    }    /**     * Removes this node from the linked list that it is a part of.     */    public void remove() {        previous.next = next;        next.previous = previous;    }    /**     * Returns a String representation of the linked list node by calling the     * toString method of the node's object.     *     * @return a String representation of the LinkedListNode.     */    public String toString() {        return object.toString();    }}