org.apache.commons.collections.list

Class AbstractLinkedList

Implemented Interfaces:
List
Known Direct Subclasses:
CursorableLinkedList, NodeCachingLinkedList

public abstract class AbstractLinkedList
extends java.lang.Object
implements List

An abstract implementation of a linked list which provides numerous points for subclasses to override.

Overridable methods are provided to change the storage node and to change how nodes are added to and removed. Hopefully, all you need for unusual subclasses is here.

Version:
$Revision: 1.9 $ $Date: 2004/04/20 23:33:54 $
Authors:
Rich Dougherty
Phil Steitz
Stephen Colebourne
Since:
Commons Collections 3.0

Nested Class Summary

protected static class
AbstractLinkedList.LinkedListIterator
A list iterator over the linked list.
protected static class
AbstractLinkedList.LinkedSubList
The sublist implementation for AbstractLinkedList.
protected static class
AbstractLinkedList.LinkedSubListIterator
A list iterator over the linked sub list.
protected static class
AbstractLinkedList.Node
A node within the linked list.

Field Summary

protected AbstractLinkedList.Node
header
A AbstractLinkedList.Node which indicates the start and end of the list and does not hold a value.
protected int
modCount
Modification count for iterators
protected int
size
The size of the list

Constructor Summary

AbstractLinkedList()
Constructor that does nothing intended for deserialization.
AbstractLinkedList(Collection coll)
Constructs a list copying data from the specified collection.

Method Summary

boolean
add(Object value)
void
add(int index, Object value)
boolean
addAll(Collection coll)
boolean
addAll(int index, Collection coll)
boolean
addFirst(Object o)
boolean
addLast(Object o)
protected void
addNode(AbstractLinkedList.Node nodeToInsert, AbstractLinkedList.Node insertBeforeNode)
Inserts a new node into the list.
protected void
addNodeAfter(AbstractLinkedList.Node node, Object value)
Creates a new node with the specified object as its value and inserts it after node.
protected void
addNodeBefore(AbstractLinkedList.Node node, Object value)
Creates a new node with the specified object as its value and inserts it before node.
void
clear()
boolean
contains(Object value)
boolean
containsAll(Collection coll)
protected AbstractLinkedList.Node
createHeaderNode()
Creates a new node with previous, next and element all set to null.
protected AbstractLinkedList.Node
createNode(Object value)
Creates a new node with the specified properties.
protected Iterator
createSubListIterator(AbstractLinkedList.LinkedSubList subList)
Creates an iterator for the sublist.
protected ListIterator
createSubListListIterator(AbstractLinkedList.LinkedSubList subList, int fromIndex)
Creates a list iterator for the sublist.
protected void
doReadObject(ObjectInputStream inputStream)
Deserializes the data held in this object to the stream specified.
protected void
doWriteObject(ObjectOutputStream outputStream)
Serializes the data held in this object to the stream specified.
boolean
equals(Object obj)
Object
get(int index)
Object
getFirst()
Object
getLast()
protected AbstractLinkedList.Node
getNode(int index, boolean endMarkerAllowed)
Gets the node at a particular index.
int
hashCode()
int
indexOf(Object value)
protected void
init()
The equivalent of a default constructor, broken out so it can be called by any constructor and by readObject.
boolean
isEmpty()
protected boolean
isEqualValue(Object value1, Object value2)
Compares two values for equals.
Iterator
iterator()
int
lastIndexOf(Object value)
ListIterator
listIterator()
ListIterator
listIterator(int fromIndex)
boolean
remove(Object value)
Object
remove(int index)
boolean
removeAll(Collection coll)
protected void
removeAllNodes()
Removes all nodes by resetting the circular list marker.
Object
removeFirst()
Object
removeLast()
protected void
removeNode(AbstractLinkedList.Node node)
Removes the specified node from the list.
boolean
retainAll(Collection coll)
Object
set(int index, Object value)
int
size()
List
subList(int fromIndexInclusive, int toIndexExclusive)
Gets a sublist of the main list.
Object[]
toArray()
Object[]
toArray(Object[] array)
String
toString()
protected void
updateNode(AbstractLinkedList.Node node, Object value)
Updates the node with a new value.

Field Details

header

protected AbstractLinkedList.Node header
A AbstractLinkedList.Node which indicates the start and end of the list and does not hold a value. The value of next is the first item in the list. The value of of previous is the last item in the list.

modCount

protected int modCount
Modification count for iterators

size

protected int size
The size of the list

Constructor Details

AbstractLinkedList

protected AbstractLinkedList()
Constructor that does nothing intended for deserialization.

If this constructor is used by a serializable subclass then the init() method must be called.


AbstractLinkedList

protected AbstractLinkedList(Collection coll)
Constructs a list copying data from the specified collection.
Parameters:
coll - the collection to copy

Method Details

add

public boolean add(Object value)

add

public void add(int index,
                Object value)

addAll

public boolean addAll(Collection coll)

addAll

public boolean addAll(int index,
                      Collection coll)

addFirst

public boolean addFirst(Object o)

addLast

public boolean addLast(Object o)

addNode

protected void addNode(AbstractLinkedList.Node nodeToInsert,
                       AbstractLinkedList.Node insertBeforeNode)
Inserts a new node into the list.
Parameters:
nodeToInsert - new node to insert
insertBeforeNode - node to insert before

addNodeAfter

protected void addNodeAfter(AbstractLinkedList.Node node,
                            Object value)
Creates a new node with the specified object as its value and inserts it after node.

This implementation uses createNode(Object) and addNode(AbstractLinkedList.Node,AbstractLinkedList.Node).

Parameters:
node - node to insert after
value - value of the newly added node

addNodeBefore

protected void addNodeBefore(AbstractLinkedList.Node node,
                             Object value)
Creates a new node with the specified object as its value and inserts it before node.

This implementation uses createNode(Object) and addNode(AbstractLinkedList.Node,AbstractLinkedList.Node).

Parameters:
node - node to insert before
value - value of the newly added node

clear

public void clear()

contains

public boolean contains(Object value)

containsAll

public boolean containsAll(Collection coll)

createHeaderNode

protected AbstractLinkedList.Node createHeaderNode()
Creates a new node with previous, next and element all set to null. This implementation creates a new empty Node. Subclasses can override this to create a different class.
Returns:
newly created node

createNode

protected AbstractLinkedList.Node createNode(Object value)
Creates a new node with the specified properties. This implementation creates a new Node with data. Subclasses can override this to create a different class.
Parameters:
value - value of the new node

createSubListIterator

protected Iterator createSubListIterator(AbstractLinkedList.LinkedSubList subList)
Creates an iterator for the sublist.
Parameters:
subList - the sublist to get an iterator for

createSubListListIterator

protected ListIterator createSubListListIterator(AbstractLinkedList.LinkedSubList subList,
                                                 int fromIndex)
Creates a list iterator for the sublist.
Parameters:
subList - the sublist to get an iterator for
fromIndex - the index to start from, relative to the sublist

doReadObject

protected void doReadObject(ObjectInputStream inputStream)
            throws IOException,
                   ClassNotFoundException
Deserializes the data held in this object to the stream specified.

The first serializable subclass must call this method from readObject.


doWriteObject

protected void doWriteObject(ObjectOutputStream outputStream)
            throws IOException
Serializes the data held in this object to the stream specified.

The first serializable subclass must call this method from writeObject.


equals

public boolean equals(Object obj)

get

public Object get(int index)

getFirst

public Object getFirst()

getLast

public Object getLast()

getNode

protected AbstractLinkedList.Node getNode(int index,
                                          boolean endMarkerAllowed)
            throws IndexOutOfBoundsException
Gets the node at a particular index.
Parameters:
index - the index, starting from 0
endMarkerAllowed - whether or not the end marker can be returned if startIndex is set to the list's size

hashCode

public int hashCode()

indexOf

public int indexOf(Object value)

init

protected void init()
The equivalent of a default constructor, broken out so it can be called by any constructor and by readObject. Subclasses which override this method should make sure they call super, so the list is initialised properly.

isEmpty

public boolean isEmpty()

isEqualValue

protected boolean isEqualValue(Object value1,
                               Object value2)
Compares two values for equals. This implementation uses the equals method. Subclasses can override this to match differently.
Parameters:
value1 - the first value to compare, may be null
value2 - the second value to compare, may be null
Returns:
true if equal

iterator

public Iterator iterator()

lastIndexOf

public int lastIndexOf(Object value)

listIterator

public ListIterator listIterator()

listIterator

public ListIterator listIterator(int fromIndex)

remove

public boolean remove(Object value)

remove

public Object remove(int index)

removeAll

public boolean removeAll(Collection coll)

removeAllNodes

protected void removeAllNodes()
Removes all nodes by resetting the circular list marker.

removeFirst

public Object removeFirst()

removeLast

public Object removeLast()

removeNode

protected void removeNode(AbstractLinkedList.Node node)
Removes the specified node from the list.
Parameters:
node - the node to remove

retainAll

public boolean retainAll(Collection coll)

set

public Object set(int index,
                  Object value)

size

public int size()

subList

public List subList(int fromIndexInclusive,
                    int toIndexExclusive)
Gets a sublist of the main list.
Parameters:
fromIndexInclusive - the index to start from
toIndexExclusive - the index to end at
Returns:
the new sublist

toArray

public Object[] toArray()

toArray

public Object[] toArray(Object[] array)

toString

public String toString()

updateNode

protected void updateNode(AbstractLinkedList.Node node,
                          Object value)
Updates the node with a new value. This implementation sets the value on the node. Subclasses can override this to record the change.
Parameters:
node - node to update
value - new value of the node

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