org.datanucleus.store.types.wrappers.backed

Class List

java.lang.Object

java.util.AbstractCollection<E>

java.util.AbstractList

org.datanucleus.store.types.wrappers.List

org.datanucleus.store.types.wrappers.backed.List

All Implemented Interfaces:

Serializable, Cloneable, Iterable, Collection, List, SCO<List>, SCOCollection<List>, SCOContainer<List>, SCOList<List>, BackedSCO

public class List
extends List
implements BackedSCO

A mutable second-class List object. This class extends AbstractList, 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	useCache

Fields inherited from class org.datanucleus.store.types.wrappers.List

delegate, ownerMmd, ownerOP

Fields inherited from class java.util.AbstractList

modCount

Constructor Summary

Constructors

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

Method Summary

Modifier and Type	Method and Description
void	add(int index, Object element) Method to add an element to the List at a position.
boolean	add(Object element) Method to add an element to the List
boolean	addAll(Collection elements) Method to add a Collection to the ArrayList.
boolean	addAll(int index, Collection elements) Method to add a collection of elements.
void	clear() Method to clear the List
Object	clone() Creates and returns a copy of this object.
boolean	contains(Object element) Accessor for whether an element is contained in the List.
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()
List	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(List c) Method to initialise the SCO from an existing value.
void	initialise(List newValue, Object oldValue) Method to initialise the SCO for use, where replacing an old value with a new value such as when calling a setter field passing in a new value.
boolean	isEmpty() Accessor for whether the List is empty.
boolean	isLoaded() Method to return if the SCO has its contents loaded.
Iterator	iterator() Accessor for an iterator for the List
int	lastIndexOf(Object element) Method to retrieve the last position of the element.
ListIterator	listIterator() Method to retrieve a List iterator for the list.
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 ArrayList.
boolean	remove(Object element) Method to remove an element from the List
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 of elements from the List.
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 ArrayList.
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 List
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, boolean makeDirty) 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.wrappers.List

attachCopy, detachCopy, getFieldName, getOwner, makeDirty, setValue

Methods inherited from class java.util.AbstractList

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

replaceAll, sort, spliterator

Methods inherited from interface java.util.Collection

parallelStream, removeIf, stream

Methods inherited from interface java.lang.Iterable

forEach

Field Detail

backingStore

protected transient ListStore backingStore

allowNulls

protected transient boolean allowNulls

useCache

protected transient boolean useCache

isCacheLoaded

protected transient boolean isCacheLoaded

Constructor Detail

List

public List(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(List newValue,
                       Object oldValue)

Description copied from interface: SCO

Method to initialise the SCO for use, where replacing an old value with a new value such as when calling a setter field passing in a new value. Note that oldValue is marked as Object since for cases where the member type is Collection the newValue could be, for example, ArrayList, and the oldValue of type Collection (representing null).

Specified by:

initialise in interface SCO<List>

Overrides:

initialise in class List

Parameters:

newValue - New value (to wrap)

oldValue - Old value (to use in deciding what needs deleting etc)

initialise

public void initialise(List c)

Method to initialise the SCO from an existing value.

Specified by:

initialise in interface SCO<List>

Overrides:

initialise in class List

Parameters:

c - The object to set from

initialise

public void initialise()

Method to initialise the SCO for use.

Specified by:

initialise in interface SCO<List>

Overrides:

initialise in class List

getValue

public List getValue()

Accessor for the unwrapped value that we are wrapping.

Specified by:

getValue in interface SCO<List>

Overrides:

getValue in class List

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<List>

Overrides:

load in class List

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<List>

Overrides:

isLoaded in class List

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,
                                  boolean makeDirty)

Method to update an embedded element in this collection.

Specified by:

updateEmbeddedElement in interface SCOCollection<List>

Overrides:

updateEmbeddedElement in class List

Parameters:

element - The element

fieldNumber - Number of field in the element

value - New value for this field

makeDirty - Whether to make the SCO field dirty.

unsetOwner

public void unsetOwner()

Method to unset the owner and field information.

Specified by:

unsetOwner in interface SCO<List>

Overrides:

unsetOwner in class List

clone

public Object clone()

Creates and returns a copy of this object.

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

Specified by:

clone in interface SCO<List>

Overrides:

clone in class List

Returns:

The cloned object

contains

public boolean contains(Object element)

Accessor for whether an element is contained in the List.

Specified by:

contains in interface Collection

Specified by:

contains in interface List

Overrides:

contains in class List

Parameters:

element - The element

Returns:

Whether the element is contained here

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 List

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 List

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 List

Parameters:

index - The item to retrieve

Returns:

The element at that position.

hashCode

public int hashCode()

Hashcode operator.

Specified by:

hashCode in interface Collection

Specified by:

hashCode in interface List

Overrides:

hashCode in class List

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 List

Parameters:

element - The element.

Returns:

The position.

isEmpty

public boolean isEmpty()

Accessor for whether the List is empty.

Specified by:

isEmpty in interface Collection

Specified by:

isEmpty in interface List

Overrides:

isEmpty in class List

Returns:

Whether it is empty.

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 List

Parameters:

element - The element

Returns:

The last position of this element in the List.

iterator

public Iterator iterator()

Accessor for an iterator for the List

Specified by:

iterator in interface Iterable

Specified by:

iterator in interface Collection

Specified by:

iterator in interface List

Overrides:

iterator in class List

Returns:

The iterator

listIterator

public ListIterator listIterator()

Method to retrieve a List iterator for the list.

Specified by:

listIterator in interface List

Overrides:

listIterator in class List

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 List

Parameters:

index - The start point

Returns:

The iterator

size

public int size()

Accessor for the size of the List

Specified by:

size in interface Collection

Specified by:

size in interface List

Overrides:

size in class List

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 List

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 List

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 List

Parameters:

a - The array to copy to

Returns:

The array

add

public boolean add(Object element)

Method to add an element to the List

Specified by:

add in interface Collection

Specified by:

add in interface List

Overrides:

add in class List

Parameters:

element - The element to add

Returns:

Whether it was added successfully.

add

public void add(int index,
                Object element)

Method to add an element to the List at a position.

Specified by:

add in interface List

Overrides:

add in class List

Parameters:

element - The element to add

index - The position

addAll

public boolean addAll(Collection elements)

Method to add a Collection to the ArrayList.

Specified by:

addAll in interface Collection

Specified by:

addAll in interface List

Overrides:

addAll in class List

Parameters:

elements - The collection

Returns:

Whether it was added ok.

addAll

public boolean addAll(int index,
                      Collection elements)

Method to add a collection of elements.

Specified by:

addAll in interface List

Overrides:

addAll in class List

Parameters:

elements - The collection of elements to add.

index - The position to add them

Returns:

Whether they were added successfully.

clear

public void clear()

Method to clear the List

Specified by:

clear in interface Collection

Specified by:

clear in interface List

Overrides:

clear in class List

remove

public boolean remove(Object element)

Method to remove an element from the List

Specified by:

remove in interface Collection

Specified by:

remove in interface List

Overrides:

remove in class List

Parameters:

element - The Element to remove

Returns:

Whether it was removed successfully.

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<List>

Overrides:

remove in class List

Parameters:

element - The element

allowCascadeDelete - Whether to allow cascade delete

Returns:

Whether it was removed successfully.

remove

public Object remove(int index)

Method to remove an element from the ArrayList.

Specified by:

remove in interface List

Overrides:

remove in class List

Parameters:

index - The element position.

Returns:

The object that was removed

removeAll

public boolean removeAll(Collection elements)

Method to remove a collection of elements from the List.

Specified by:

removeAll in interface Collection

Specified by:

removeAll in interface List

Overrides:

removeAll in class List

Parameters:

elements - Collection of elements to remove

Returns:

Whether it was successful.

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 List

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<List>

Overrides:

set in class List

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 ArrayList.

Specified by:

set in interface List

Overrides:

set in class List

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 List

Returns:

the replaced object

Throws:

ObjectStreamException - if an error occurs