org.datanucleus.store.types.wrappers.backed

Class Collection<E>

java.lang.Object

java.util.AbstractCollection<E>

org.datanucleus.store.types.wrappers.Collection<E>

org.datanucleus.store.types.wrappers.backed.Collection<E>

All Implemented Interfaces:

Serializable, Cloneable, Iterable<E>, Collection<E>, SCO<Collection<E>>, SCOCollection<Collection<E>,E>, SCOContainer<Collection<E>>, BackedSCO

public class Collection<E>
extends Collection<E>
implements BackedSCO

A mutable second-class Collection object. This class extends Collection, using that class to contain the current objects, and the backing CollectionStore 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 CollectionStore<E>	backingStore
protected boolean	initialising
protected boolean	isCacheLoaded
protected boolean	useCache

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

delegate, ownerMmd, ownerOP

Constructor Summary

Constructors

Constructor and Description
Collection(ObjectProvider op, AbstractMemberMetaData mmd) Constructor.
Collection(ObjectProvider ownerOP, AbstractMemberMetaData mmd, boolean allowNulls, CollectionStore backingStore) Constructor used when creating a Collection for "Map.values" with specified backing store.

Method Summary

Modifier and Type	Method and Description
boolean	add(E element) Method to add an element to the Collection.
boolean	addAll(Collection c) Method to add a collection of elements.
void	clear() Method to clear the Collection.
Object	clone() Creates and returns a copy of this object.
boolean	contains(Object element) Accessor for whether an element is contained in the Collection.
boolean	containsAll(Collection c) Accessor for whether a collection of elements are contained here.
boolean	equals(Object o) Equality operator.
void	forEach(java.util.function.Consumer action)
Store	getBackingStore()
Collection	getValue() Accessor for the unwrapped value that we are wrapping.
int	hashCode() Hashcode operator.
void	initialise() Method to initialise the SCO for use.
void	initialise(Collection c) Method to initialise the SCO from an existing value.
void	initialise(Collection<E> 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 Collection is empty.
boolean	isLoaded() Method to return if the SCO has its contents loaded.
Iterator<E>	iterator() Accessor for an iterator for the Collection.
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.
java.util.stream.Stream	parallelStream()
boolean	remove(Object element) Method to remove an element from the Collection.
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.
boolean	retainAll(Collection c) Method to retain a Collection of elements (and remove all others).
int	size() Accessor for the size of the Collection.
Spliterator	spliterator()
java.util.stream.Stream	stream()
Object[]	toArray() Method to return the Collection as an array.
Object[]	toArray(Object[] a) Method to return the Collection as an array.
String	toString() Method to return the Collection as a String.
void	unsetOwner() Method to unset the owner state manager and backing store information.
void	updateEmbeddedElement(E 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.Collection

attachCopy, detachCopy, getFieldName, getOwner, makeDirty, setValue

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Collection

removeIf

Field Detail

backingStore

protected transient CollectionStore<E> backingStore

allowNulls

protected transient boolean allowNulls

useCache

protected transient boolean useCache

isCacheLoaded

protected transient boolean isCacheLoaded

initialising

protected transient boolean initialising

Constructor Detail

Collection

public Collection(ObjectProvider op,
                  AbstractMemberMetaData mmd)

Constructor.

Parameters:

op - The ObjectProvider for this collection.

mmd - Metadata for the member

Collection

public Collection(ObjectProvider ownerOP,
                  AbstractMemberMetaData mmd,
                  boolean allowNulls,
                  CollectionStore backingStore)

Constructor used when creating a Collection for "Map.values" with specified backing store.

Parameters:

ownerOP - ObjectProvider for the owning object

mmd - Metadata for the member

allowNulls - Whether nulls are allowed

backingStore - The backing store

Method Detail

initialise

public void initialise(Collection<E> 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<Collection<E>>

Overrides:

initialise in class Collection<E>

Parameters:

newValue - New value (to wrap)

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

initialise

public void initialise(Collection c)

Method to initialise the SCO from an existing value.

Specified by:

initialise in interface SCO<Collection<E>>

Overrides:

initialise in class Collection<E>

Parameters:

c - The object to set from

initialise

public void initialise()

Method to initialise the SCO for use.

Specified by:

initialise in interface SCO<Collection<E>>

Overrides:

initialise in class Collection<E>

getValue

public Collection getValue()

Accessor for the unwrapped value that we are wrapping.

Specified by:

getValue in interface SCO<Collection<E>>

Overrides:

getValue in class Collection<E>

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<Collection<E>>

Overrides:

load in class Collection<E>

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<Collection<E>>

Specified by:

isLoaded in interface BackedSCO

Overrides:

isLoaded in class Collection<E>

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(E element,
                                  int fieldNumber,
                                  Object value,
                                  boolean makeDirty)

Method to update an embedded element in this collection.

Specified by:

updateEmbeddedElement in interface SCOCollection<Collection<E>,E>

Overrides:

updateEmbeddedElement in class Collection<E>

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 state manager and backing store information.

Specified by:

unsetOwner in interface SCO<Collection<E>>

Overrides:

unsetOwner in class Collection<E>

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<Collection<E>>

Overrides:

clone in class Collection<E>

Returns:

A clone of the object

contains

public boolean contains(Object element)

Accessor for whether an element is contained in the Collection.

Specified by:

contains in interface Collection<E>

Overrides:

contains in class Collection<E>

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<E>

Overrides:

containsAll in class Collection<E>

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<E>

Overrides:

equals in class Collection<E>

Parameters:

o - The object to compare against.

Returns:

Whether this object is the same.

forEach

public void forEach(java.util.function.Consumer action)

Specified by:

forEach in interface Iterable<E>

Overrides:

forEach in class Collection<E>

hashCode

public int hashCode()

Hashcode operator.

Specified by:

hashCode in interface Collection<E>

Overrides:

hashCode in class Collection<E>

Returns:

The Hash code.

isEmpty

public boolean isEmpty()

Accessor for whether the Collection is empty.

Specified by:

isEmpty in interface Collection<E>

Overrides:

isEmpty in class Collection<E>

Returns:

Whether it is empty.

iterator

public Iterator<E> iterator()

Accessor for an iterator for the Collection.

Specified by:

iterator in interface Iterable<E>

Specified by:

iterator in interface Collection<E>

Overrides:

iterator in class Collection<E>

Returns:

The iterator

size

public int size()

Accessor for the size of the Collection.

Specified by:

size in interface Collection<E>

Overrides:

size in class Collection<E>

Returns:

The size

toArray

public Object[] toArray()

Method to return the Collection as an array.

Specified by:

toArray in interface Collection<E>

Overrides:

toArray in class Collection<E>

Returns:

The array

toArray

public Object[] toArray(Object[] a)

Method to return the Collection as an array.

Specified by:

toArray in interface Collection<E>

Overrides:

toArray in class Collection<E>

Parameters:

a - The array to write the results to

Returns:

The array

toString

public String toString()

Method to return the Collection as a String.

Overrides:

toString in class AbstractCollection<E>

Returns:

The string form

add

public boolean add(E element)

Method to add an element to the Collection.

Specified by:

add in interface Collection<E>

Overrides:

add in class Collection<E>

Parameters:

element - The element to add

Returns:

Whether it was added successfully.

addAll

public boolean addAll(Collection c)

Method to add a collection of elements.

Specified by:

addAll in interface Collection<E>

Overrides:

addAll in class Collection<E>

Parameters:

c - The collection of elements to add.

Returns:

Whether they were added successfully.

clear

public void clear()

Method to clear the Collection.

Specified by:

clear in interface Collection<E>

Overrides:

clear in class Collection<E>

remove

public boolean remove(Object element)

Method to remove an element from the Collection.

Specified by:

remove in interface Collection<E>

Overrides:

remove in class Collection<E>

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<Collection<E>,E>

Overrides:

remove in class Collection<E>

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 of elements.

Specified by:

removeAll in interface Collection<E>

Overrides:

removeAll in class Collection<E>

Parameters:

elements - The collection to remove

Returns:

Whether they were removed successfully.

retainAll

public boolean retainAll(Collection c)

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

Specified by:

retainAll in interface Collection<E>

Overrides:

retainAll in class Collection<E>

Parameters:

c - The collection to retain

Returns:

Whether they were retained successfully.

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 Collection<E>

Returns:

the replaced object

Throws:

ObjectStreamException - if an error occurs

spliterator

public Spliterator spliterator()

Specified by:

spliterator in interface Iterable<E>

Specified by:

spliterator in interface Collection<E>

Overrides:

spliterator in class Collection<E>

stream

public java.util.stream.Stream stream()

Specified by:

stream in interface Collection<E>

Overrides:

stream in class Collection<E>

parallelStream

public java.util.stream.Stream parallelStream()

Specified by:

parallelStream in interface Collection<E>

Overrides:

parallelStream in class Collection<E>