Package org.jivesoftware.util

Class LinkedListNode<E>

java.lang.Object

org.jivesoftware.util.LinkedListNode<E>

Type Parameters:

E - the type of node

public class LinkedListNode<E>
extends Object

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.

Author:

Jive Software

See Also:

LinkedList

Field Summary

Fields

Modifier and Type	Field	Description
LinkedListNode<E>	next
E	object
LinkedListNode<E>	previous
long	timestamp	This class is further customized for the CoolServlets cache system.

Constructor Summary

Constructors

Constructor	Description
LinkedListNode()	Constructs an self-referencing node.
LinkedListNode(E object, LinkedListNode<E> next, LinkedListNode<E> previous)	Constructs a new linked list node.

Method Summary

Modifier and Type	Method	Description
LinkedListNode<E>	insert(LinkedListNode<E> next, LinkedListNode<E> previous)	Inserts this node into the linked list that it will be a part of.
LinkedListNode<E>	remove()	Removes this node from the linked list that it was a part of.
String	toString()	Returns a String representation of the linked list node by calling the toString method of the node's object.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

previous

public LinkedListNode<E> previous

next

public LinkedListNode<E> next

object

public E object

timestamp

public long timestamp

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.

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.

Constructor Detail

LinkedListNode

public LinkedListNode()

Constructs an self-referencing node. This node acts as a start/end sentinel when traversing nodes in a LinkedList.

LinkedListNode

public LinkedListNode(E object,
                      LinkedListNode<E> next,
                      LinkedListNode<E> previous)

Constructs a new linked list node.

Parameters:

object - the Object that the node represents.

next - a reference to the next LinkedListNode in the list.

previous - a reference to the previous LinkedListNode in the list.

Method Detail

remove

public LinkedListNode<E> remove()

Removes this node from the linked list that it was a part of.

Returns:

This node; next and previous references dropped

insert

public LinkedListNode<E> insert(LinkedListNode<E> next,
                                LinkedListNode<E> previous)

Inserts this node into the linked list that it will be a part of.

Parameters:

next - a reference to the next LinkedListNode in the list.

previous - a reference to the previous LinkedListNode in the list.

Returns:

This node, updated to reflect previous/next changes

toString

public String toString()

Returns a String representation of the linked list node by calling the toString method of the node's object.

Overrides:

toString in class Object

Returns:

a String representation of the LinkedListNode.