org.datanucleus.store.types.wrappers.backed

Class HashSet<E>

java.lang.Object

java.util.AbstractCollection<E>

java.util.AbstractSet<E>

java.util.HashSet<E>

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

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

All Implemented Interfaces:

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

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

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

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

delegate, ownerMmd, ownerOP

Constructor Summary

Constructors

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

Method Summary

Modifier and Type	Method and Description
boolean	add(E element) Method to add an element to the HashSet.
boolean	addAll(Collection c) Method to add a collection to the HashSet.
void	clear() Method to clear the HashSet
Object	clone() Creates and returns a copy of this object.
boolean	contains(Object element) Accessor for whether an element is contained in this Set.
boolean	containsAll(Collection c) Accessor for whether a collection is contained in this Set.
boolean	equals(Object o)
Store	getBackingStore()
HashSet	getValue() Accessor for the unwrapped value that we are wrapping.
int	hashCode()
void	initialise() Method to initialise the SCO for use.
void	initialise(HashSet c) Method to initialise the SCO from an existing value.
void	initialise(HashSet<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 HashSet is empty.
boolean	isLoaded() Method to return if the SCO has its contents loaded.
Iterator<E>	iterator() Accessor for an iterator for the Set.
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 HashSet.
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 all elements from the collection from the HashSet.
boolean	retainAll(Collection c) Method to retain a Collection of elements (and remove all others).
int	size() Accessor for the size of the HashSet.
Spliterator	spliterator()
java.util.stream.Stream	stream()
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(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.HashSet

attachCopy, detachCopy, forEach, getFieldName, getOwner, makeDirty, removeIf, setValue

Methods inherited from class java.util.AbstractCollection

toString

Methods inherited from class java.lang.Object

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

Field Detail

backingStore

protected transient SetStore<E> backingStore

allowNulls

protected transient boolean allowNulls

useCache

protected transient boolean useCache

isCacheLoaded

protected transient boolean isCacheLoaded

initialising

protected transient boolean initialising

Constructor Detail

HashSet

public HashSet(ObjectProvider op,
               AbstractMemberMetaData mmd)

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

Parameters:

op - The owner ObjectProvider

mmd - Metadata for the member

Method Detail

initialise

public void initialise(HashSet<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<HashSet<E>>

Overrides:

initialise in class HashSet<E>

Parameters:

newValue - New value (to wrap)

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

initialise

public void initialise(HashSet c)

Method to initialise the SCO from an existing value.

Specified by:

initialise in interface SCO<HashSet<E>>

Overrides:

initialise in class HashSet<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<HashSet<E>>

Overrides:

initialise in class HashSet<E>

getValue

public HashSet getValue()

Accessor for the unwrapped value that we are wrapping.

Specified by:

getValue in interface SCO<HashSet<E>>

Overrides:

getValue in class HashSet<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<HashSet<E>>

Overrides:

load in class HashSet<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<HashSet<E>>

Overrides:

isLoaded in class HashSet<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<HashSet<E>,E>

Overrides:

updateEmbeddedElement in class HashSet<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 and field information.

Specified by:

unsetOwner in interface SCO<HashSet<E>>

Overrides:

unsetOwner in class HashSet<E>

clone

public Object clone()

Creates and returns a copy of this object.

Specified by:

clone in interface SCO<HashSet<E>>

Overrides:

clone in class HashSet<E>

Returns:

The cloned object

contains

public boolean contains(Object element)

Accessor for whether an element is contained in this Set.

Specified by:

contains in interface Collection<E>

Specified by:

contains in interface Set<E>

Overrides:

contains in class HashSet<E>

Parameters:

element - The element

Returns:

Whether it is contained.

containsAll

public boolean containsAll(Collection c)

Accessor for whether a collection is contained in this Set.

Specified by:

containsAll in interface Collection<E>

Specified by:

containsAll in interface Set<E>

Overrides:

containsAll in class HashSet<E>

Parameters:

c - The collection

Returns:

Whether it is contained.

equals

public boolean equals(Object o)

Specified by:

equals in interface Collection<E>

Specified by:

equals in interface Set<E>

Overrides:

equals in class HashSet<E>

hashCode

public int hashCode()

Specified by:

hashCode in interface Collection<E>

Specified by:

hashCode in interface Set<E>

Overrides:

hashCode in class HashSet<E>

isEmpty

public boolean isEmpty()

Accessor for whether the HashSet is empty.

Specified by:

isEmpty in interface Collection<E>

Specified by:

isEmpty in interface Set<E>

Overrides:

isEmpty in class HashSet<E>

Returns:

Whether it is empty.

iterator

public Iterator<E> iterator()

Accessor for an iterator for the Set.

Specified by:

iterator in interface Iterable<E>

Specified by:

iterator in interface Collection<E>

Specified by:

iterator in interface Set<E>

Overrides:

iterator in class HashSet<E>

Returns:

The iterator

size

public int size()

Accessor for the size of the HashSet.

Specified by:

size in interface Collection<E>

Specified by:

size in interface Set<E>

Overrides:

size in class HashSet<E>

Returns:

The size.

toArray

public Object[] toArray()

Method to return the list as an array.

Specified by:

toArray in interface Collection<E>

Specified by:

toArray in interface Set<E>

Overrides:

toArray in class HashSet<E>

Returns:

The array

toArray

public Object[] toArray(Object[] a)

Method to return the list as an array.

Specified by:

toArray in interface Collection<E>

Specified by:

toArray in interface Set<E>

Overrides:

toArray in class HashSet<E>

Parameters:

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

Returns:

The array

add

public boolean add(E element)

Method to add an element to the HashSet.

Specified by:

add in interface Collection<E>

Specified by:

add in interface Set<E>

Overrides:

add in class HashSet<E>

Parameters:

element - The new element

Returns:

Whether it was added ok.

addAll

public boolean addAll(Collection c)

Method to add a collection to the HashSet.

Specified by:

addAll in interface Collection<E>

Specified by:

addAll in interface Set<E>

Overrides:

addAll in class HashSet<E>

Parameters:

c - The collection

Returns:

Whether it was added ok.

clear

public void clear()

Method to clear the HashSet

Specified by:

clear in interface Collection<E>

Specified by:

clear in interface Set<E>

Overrides:

clear in class HashSet<E>

remove

public boolean remove(Object element)

Method to remove an element from the HashSet.

Specified by:

remove in interface Collection<E>

Specified by:

remove in interface Set<E>

Overrides:

remove in class HashSet<E>

Parameters:

element - The element

Returns:

Whether it 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<HashSet<E>,E>

Overrides:

remove in class HashSet<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 all elements from the collection from the HashSet.

Specified by:

removeAll in interface Collection<E>

Specified by:

removeAll in interface Set<E>

Overrides:

removeAll in class HashSet<E>

Parameters:

elements - The collection of elements to remove

Returns:

Whether it was removed ok.

retainAll

public boolean retainAll(Collection c)

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

Specified by:

retainAll in interface Collection<E>

Specified by:

retainAll in interface Set<E>

Overrides:

retainAll in class HashSet<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 HashSet<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>

Specified by:

spliterator in interface Set<E>

Overrides:

spliterator in class HashSet<E>

stream

public java.util.stream.Stream stream()

Specified by:

stream in interface Collection<E>

Overrides:

stream in class HashSet<E>

parallelStream

public java.util.stream.Stream parallelStream()

Specified by:

parallelStream in interface Collection<E>

Overrides:

parallelStream in class HashSet<E>