org.datanucleus.store.types.backed

Class LinkedList

java.lang.Object

java.util.AbstractCollection<E>

java.util.AbstractList<E>

java.util.AbstractSequentialList<E>

java.util.LinkedList

org.datanucleus.store.types.simple.LinkedList

org.datanucleus.store.types.backed.LinkedList

All Implemented Interfaces:

Serializable, Cloneable, Iterable, Collection, Deque, List, Queue, BackedSCO, SCO, SCOCollection, SCOContainer, SCOList

public class LinkedList
extends LinkedList
implements BackedSCO

A mutable second-class LinkedList object. This class extends LinkedList, using that class to contain the current objects, and the backing ListStore to be the interface to the datastore. A "backing store" is not present for datastores that dont use DatastoreClass, or if the container is serialised or non-persistent.

Modes of Operation

The user can operate the list in 2 modes. The cached mode will use an internal cache of the elements (in the "delegate") reading them at the first opportunity and then using the cache thereafter. The non-cached mode will just go direct to the "backing store" each call.

Mutators

When the "backing store" is present any updates are passed direct to the datastore as well as to the "delegate". If the "backing store" isn't present the changes are made to the "delegate" only.

Accessors

When any accessor method is invoked, it typically checks whether the container has been loaded from its "backing store" (where present) and does this as necessary. Some methods (size()) just check if everything is loaded and use the delegate if possible, otherwise going direct to the datastore.

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected boolean	allowNulls
protected ListStore	backingStore
protected boolean	isCacheLoaded
protected boolean	queued
protected boolean	useCache

Fields inherited from class org.datanucleus.store.types.simple.LinkedList

delegate, LOCALISER, ownerMmd, ownerOP

Fields inherited from class java.util.AbstractList

modCount

Constructor Summary

Constructors

Constructor and Description
LinkedList(ObjectProvider ownerOP, AbstractMemberMetaData mmd) Constructor, using the ObjectProvider of the "owner" and the field name.

Method Summary

Methods

Modifier and Type	Method and Description
void	add(int index, Object element) Method to add an element to a position in the LinkedList.
boolean	add(Object element) Method to add an element to the LinkedList.
boolean	addAll(Collection elements) Method to add a Collection to the LinkedList.
boolean	addAll(int index, Collection elements) Method to add a Collection to a position in the LinkedList.
void	addFirst(Object element) Method to add an element as first in the LinkedList.
void	addLast(Object element) Method to add an element as last in the LinkedList.
void	clear() Method to clear the LinkedList.
Object	clone() Clone operator to return a copy of this object.
boolean	contains(Object element) Method to return if the list contains this element.
boolean	containsAll(Collection c) Accessor for whether a collection of elements are contained here.
boolean	equals(Object o) Equality operator.
Object	get(int index) Method to retrieve an element no.
Store	getBackingStore()
Object	getFirst() Method to retrieve the first element.
Object	getLast() Method to retrieve the last element.
Object	getValue() Accessor for the unwrapped value that we are wrapping.
int	hashCode() Hashcode operator.
int	indexOf(Object element) Method to the position of an element.
void	initialise() Method to initialise the SCO for use.
void	initialise(Object o, boolean forInsert, boolean forUpdate) Method to initialise the SCO from an existing value.
boolean	isEmpty() Accessor for whether the LinkedList is empty.
boolean	isLoaded() Method to return if the SCO has its contents loaded.
Iterator	iterator() Method to retrieve an iterator for the list.
int	lastIndexOf(Object element) Method to retrieve the last position of the element.
ListIterator	listIterator(int index) Method to retrieve a List iterator for the list from the index.
void	load() Method to effect the load of the data in the SCO.
protected void	loadFromStore() Method to load all elements from the "backing store" where appropriate.
Object	remove(int index) Method to remove an element from the LinkedList.
boolean	remove(Object element) Method to remove an element from the LinkedList.
boolean	remove(Object element, boolean allowCascadeDelete) Method to remove an element from the collection, and observe the flag for whether to allow cascade delete.
boolean	removeAll(Collection elements) Method to remove a Collection from the LinkedList.
Object	removeFirst() Method to remove the first element from the LinkedList.
Object	removeLast() Method to remove the last element from the LinkedList.
boolean	retainAll(Collection c) Method to retain a Collection of elements (and remove all others).
Object	set(int index, Object element) Method to set the element at a position in the LinkedList.
Object	set(int index, Object element, boolean allowDependentField) Wrapper addition that allows turning off of the dependent-field checks when doing the position setting.
int	size() Accessor for the size of the LinkedList.
List	subList(int from, int to) Accessor for the subList of elements between from and to of the List
Object[]	toArray() Method to return the list as an array.
Object[]	toArray(Object[] a) Method to return the list as an array.
void	unsetOwner() Method to unset the owner and field information.
void	updateEmbeddedElement(Object element, int fieldNumber, Object value) Method to update an embedded element in this collection.
protected Object	writeReplace() The writeReplace method is called when ObjectOutputStream is preparing to write the object to the stream.

Methods inherited from class org.datanucleus.store.types.simple.LinkedList

attachCopy, detachCopy, getFieldName, getOwner, makeDirty

Methods inherited from class java.util.LinkedList

descendingIterator, element, offer, offerFirst, offerLast, peek, peekFirst, peekLast, poll, pollFirst, pollLast, pop, push, remove, removeFirstOccurrence, removeLastOccurrence

Methods inherited from class java.util.AbstractList

listIterator, removeRange

Methods inherited from class java.util.AbstractCollection

toString

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.util.List

listIterator

Field Detail

backingStore

protected transient ListStore backingStore

allowNulls

protected transient boolean allowNulls

useCache

protected transient boolean useCache

isCacheLoaded

protected transient boolean isCacheLoaded

queued

protected transient boolean queued

Constructor Detail

LinkedList

public LinkedList(ObjectProvider ownerOP,
          AbstractMemberMetaData mmd)

Constructor, using the ObjectProvider of the "owner" and the field name.

Parameters:

ownerOP - The owner ObjectProvider

mmd - Metadata for the member

Method Detail

initialise

public void initialise(Object o,
              boolean forInsert,
              boolean forUpdate)

Method to initialise the SCO from an existing value.

Specified by:

initialise in interface SCO

Overrides:

initialise in class LinkedList

Parameters:

o - The object to set from

forInsert - Whether the object needs inserting in the datastore with this value

forUpdate - Whether to update the datastore with this value

initialise

public void initialise()

Method to initialise the SCO for use.

Specified by:

initialise in interface SCO

Overrides:

initialise in class LinkedList

getValue

public Object getValue()

Accessor for the unwrapped value that we are wrapping.

Specified by:

getValue in interface SCO

Overrides:

getValue in class LinkedList

Returns:

The unwrapped value

load

public void load()

Method to effect the load of the data in the SCO. Used when the SCO supports lazy-loading to tell it to load all now.

Specified by:

load in interface SCOContainer

Overrides:

load in class LinkedList

isLoaded

public boolean isLoaded()

Method to return if the SCO has its contents loaded. If the SCO doesn't support lazy loading will just return true.

Specified by:

isLoaded in interface SCOContainer

Overrides:

isLoaded in class LinkedList

Returns:

Whether it is loaded

loadFromStore

protected void loadFromStore()

Method to load all elements from the "backing store" where appropriate.

getBackingStore

public Store getBackingStore()

Specified by:

getBackingStore in interface BackedSCO

updateEmbeddedElement

public void updateEmbeddedElement(Object element,
                         int fieldNumber,
                         Object value)

Method to update an embedded element in this collection.

Specified by:

updateEmbeddedElement in interface SCOCollection

Overrides:

updateEmbeddedElement in class LinkedList

Parameters:

element - The element

fieldNumber - Number of field in the element

value - New value for this field

unsetOwner

public void unsetOwner()

Method to unset the owner and field information.

Specified by:

unsetOwner in interface SCO

Overrides:

unsetOwner in class LinkedList

clone

public Object clone()

Clone operator to return a copy of this object.

Mutable second-class Objects are required to provide a public clone method in order to allow for copying PersistenceCapable objects. In contrast to Object.clone(), this method must not throw a CloneNotSupportedException.

Specified by:

clone in interface SCO

Overrides:

clone in class LinkedList

Returns:

The cloned object

contains

public boolean contains(Object element)

Method to return if the list contains this element.

Specified by:

contains in interface Collection

Specified by:

contains in interface Deque

Specified by:

contains in interface List

Overrides:

contains in class LinkedList

Parameters:

element - The element

Returns:

Whether it is contained

containsAll

public boolean containsAll(Collection c)

Accessor for whether a collection of elements are contained here.

Specified by:

containsAll in interface Collection

Specified by:

containsAll in interface List

Overrides:

containsAll in class LinkedList

Parameters:

c - The collection of elements.

Returns:

Whether they are contained.

equals

public boolean equals(Object o)

Equality operator.

Specified by:

equals in interface Collection

Specified by:

equals in interface List

Overrides:

equals in class LinkedList

Parameters:

o - The object to compare against.

Returns:

Whether this object is the same.

get

public Object get(int index)

Method to retrieve an element no.

Specified by:

get in interface List

Overrides:

get in class LinkedList

Parameters:

index - The item to retrieve

Returns:

The element at that position.

getFirst

public Object getFirst()

Method to retrieve the first element.

Specified by:

getFirst in interface Deque

Overrides:

getFirst in class LinkedList

Returns:

The first element

getLast

public Object getLast()

Method to retrieve the last element.

Specified by:

getLast in interface Deque

Overrides:

getLast in class LinkedList

Returns:

The last element

hashCode

public int hashCode()

Hashcode operator.

Specified by:

hashCode in interface Collection

Specified by:

hashCode in interface List

Overrides:

hashCode in class LinkedList

Returns:

The Hash code.

indexOf

public int indexOf(Object element)

Method to the position of an element.

Specified by:

indexOf in interface List

Overrides:

indexOf in class LinkedList

Parameters:

element - The element.

Returns:

The position.

isEmpty

public boolean isEmpty()

Accessor for whether the LinkedList is empty.

Specified by:

isEmpty in interface Collection

Specified by:

isEmpty in interface List

Overrides:

isEmpty in class LinkedList

Returns:

Whether it is empty.

iterator

public Iterator iterator()

Method to retrieve an iterator for the list.

Specified by:

iterator in interface Iterable

Specified by:

iterator in interface Collection

Specified by:

iterator in interface Deque

Specified by:

iterator in interface List

Overrides:

iterator in class LinkedList

Returns:

The iterator

listIterator

public ListIterator listIterator(int index)

Method to retrieve a List iterator for the list from the index.

Specified by:

listIterator in interface List

Overrides:

listIterator in class LinkedList

Parameters:

index - The start point

Returns:

The iterator

lastIndexOf

public int lastIndexOf(Object element)

Method to retrieve the last position of the element.

Specified by:

lastIndexOf in interface List

Overrides:

lastIndexOf in class LinkedList

Parameters:

element - The element

Returns:

The last position of this element in the List.

size

public int size()

Accessor for the size of the LinkedList.

Specified by:

size in interface Collection

Specified by:

size in interface Deque

Specified by:

size in interface List

Overrides:

size in class LinkedList

Returns:

The size.

subList

public List subList(int from,
           int to)

Accessor for the subList of elements between from and to of the List

Specified by:

subList in interface List

Overrides:

subList in class LinkedList

Parameters:

from - Start index (inclusive)

to - End index (exclusive)

Returns:

The subList

toArray

public Object[] toArray()

Method to return the list as an array.

Specified by:

toArray in interface Collection

Specified by:

toArray in interface List

Overrides:

toArray in class LinkedList

Returns:

The array

toArray

public Object[] toArray(Object[] a)

Method to return the list as an array.

Specified by:

toArray in interface Collection

Specified by:

toArray in interface List

Overrides:

toArray in class LinkedList

Parameters:

a - The runtime types of the array being defined by this param

Returns:

The array

add

public void add(int index,
       Object element)

Method to add an element to a position in the LinkedList.

Specified by:

add in interface List

Overrides:

add in class LinkedList

Parameters:

index - The position

element - The new element

add

public boolean add(Object element)

Method to add an element to the LinkedList.

Specified by:

add in interface Collection

Specified by:

add in interface Deque

Specified by:

add in interface List

Specified by:

add in interface Queue

Overrides:

add in class LinkedList

Parameters:

element - The new element

Returns:

Whether it was added ok.

addAll

public boolean addAll(Collection elements)

Method to add a Collection to the LinkedList.

Specified by:

addAll in interface Collection

Specified by:

addAll in interface List

Overrides:

addAll in class LinkedList

Parameters:

elements - The collection

Returns:

Whether it was added ok.

addAll

public boolean addAll(int index,
             Collection elements)

Method to add a Collection to a position in the LinkedList.

Specified by:

addAll in interface List

Overrides:

addAll in class LinkedList

Parameters:

index - Position to insert the collection.

elements - The collection

Returns:

Whether it was added ok.

addFirst

public void addFirst(Object element)

Method to add an element as first in the LinkedList.

Specified by:

addFirst in interface Deque

Overrides:

addFirst in class LinkedList

Parameters:

element - The new element

addLast

public void addLast(Object element)

Method to add an element as last in the LinkedList.

Specified by:

addLast in interface Deque

Overrides:

addLast in class LinkedList

Parameters:

element - The new element

clear

public void clear()

Method to clear the LinkedList.

Specified by:

clear in interface Collection

Specified by:

clear in interface List

Overrides:

clear in class LinkedList

remove

public Object remove(int index)

Method to remove an element from the LinkedList.

Specified by:

remove in interface List

Overrides:

remove in class LinkedList

Parameters:

index - The element position.

Returns:

The object that was removed

remove

public boolean remove(Object element)

Method to remove an element from the LinkedList.

Specified by:

remove in interface Collection

Specified by:

remove in interface Deque

Specified by:

remove in interface List

Overrides:

remove in class LinkedList

Parameters:

element - The element

Returns:

Whether the object was removed ok

remove

public boolean remove(Object element,
             boolean allowCascadeDelete)

Method to remove an element from the collection, and observe the flag for whether to allow cascade delete.

Specified by:

remove in interface SCOCollection

Overrides:

remove in class LinkedList

Parameters:

element - The element

allowCascadeDelete - Whether to allow cascade delete

Returns:

Whether it was removed successfully.

removeAll

public boolean removeAll(Collection elements)

Method to remove a Collection from the LinkedList.

Specified by:

removeAll in interface Collection

Specified by:

removeAll in interface List

Overrides:

removeAll in class LinkedList

Parameters:

elements - The collection

Returns:

Whether it was removed ok.

removeFirst

public Object removeFirst()

Method to remove the first element from the LinkedList.

Specified by:

removeFirst in interface Deque

Overrides:

removeFirst in class LinkedList

Returns:

The object that was removed

removeLast

public Object removeLast()

Method to remove the last element from the LinkedList.

Specified by:

removeLast in interface Deque

Overrides:

removeLast in class LinkedList

Returns:

The object that was removed

retainAll

public boolean retainAll(Collection c)

Method to retain a Collection of elements (and remove all others).

Specified by:

retainAll in interface Collection

Specified by:

retainAll in interface List

Overrides:

retainAll in class LinkedList

Parameters:

c - The collection to retain

Returns:

Whether they were retained successfully.

set

public Object set(int index,
         Object element,
         boolean allowDependentField)

Wrapper addition that allows turning off of the dependent-field checks when doing the position setting. This means that we can prevent the deletion of the object that was previously in that position. This particular feature is used when attaching a list field and where some elements have changed positions.

Specified by:

set in interface SCOList

Overrides:

set in class LinkedList

Parameters:

index - The position

element - The new element

allowDependentField - Whether to allow dependent-field deletes

Returns:

The element previously at that position

set

public Object set(int index,
         Object element)

Method to set the element at a position in the LinkedList.

Specified by:

set in interface List

Overrides:

set in class LinkedList

Parameters:

index - The position

element - The new element

Returns:

The element previously at that position

writeReplace

protected Object writeReplace()
                       throws ObjectStreamException

The writeReplace method is called when ObjectOutputStream is preparing to write the object to the stream. The ObjectOutputStream checks whether the class defines the writeReplace method. If the method is defined, the writeReplace method is called to allow the object to designate its replacement in the stream. The object returned should be either of the same type as the object passed in or an object that when read and resolved will result in an object of a type that is compatible with all references to the object.

Overrides:

writeReplace in class LinkedList

Returns:

the replaced object

Throws:

ObjectStreamException