org.datanucleus.store.types.simple

Class Queue

java.lang.Object

java.util.AbstractCollection<E>

java.util.AbstractQueue

org.datanucleus.store.types.simple.Queue

All Implemented Interfaces:

Serializable, Cloneable, Iterable, Collection, Queue, SCO, SCOCollection, SCOContainer, SCOMtoN

Direct Known Subclasses:

Queue

public class Queue
extends AbstractQueue
implements SCOCollection, SCOMtoN, Cloneable, Serializable

A mutable second-class Queue object. This is the simplified form that intercepts mutators and marks the field as dirty. It also handles cascade-delete triggering for persistable elements.

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected Queue	delegate The internal "delegate".
protected static Localiser	LOCALISER
protected AbstractMemberMetaData	ownerMmd
protected ObjectProvider	ownerOP

Constructor Summary

Constructors

Constructor and Description
Queue(ObjectProvider ownerOP, AbstractMemberMetaData mmd) Constructor.

Method Summary

Methods

Modifier and Type	Method and Description
boolean	add(Object element) Method to add an element to the Collection.
boolean	addAll(Collection elements) Method to add a collection of elements.
void	attachCopy(Object value) Method to return an attached copy of the passed (detached) value.
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.
Object	detachCopy(FetchPlanState state) Method to return a detached copy of the container.
boolean	equals(Object o) Equality operator.
String	getFieldName() Accessor for the field name.
Object	getOwner() Accessor for the owner object.
Object	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(Object o, boolean forInsert, boolean forUpdate) Method to initialise the SCO from an existing value.
protected void	initialiseDelegate() Convenience method to set up the delegate respecting any comparator specified in MetaData.
boolean	isEmpty() Accessor for whether the Collection is empty.
boolean	isLoaded() Method to return if the SCO has its contents loaded.
Iterator	iterator() Accessor for an iterator for the Collection.
void	load() Method to effect the load of the data in the SCO.
void	makeDirty() Utility to mark the object as dirty
boolean	offer(Object element) Method to offer an element to the Queue.
Object	peek() Method to peek at the next element in the Queue.
Object	poll() Method to poll the next element in the Queue.
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 List
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.
Object[]	toArray() Method to return the Collection as an array.
Object[]	toArray(Object[] a) Method to return the Collection 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 java.util.AbstractQueue

element, remove

Methods inherited from class java.util.AbstractCollection

toString

Methods inherited from class java.lang.Object

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

Field Detail

LOCALISER

protected static final Localiser LOCALISER

ownerOP

protected ObjectProvider ownerOP

ownerMmd

protected AbstractMemberMetaData ownerMmd

delegate

protected Queue delegate

The internal "delegate".

Constructor Detail

Queue

public Queue(ObjectProvider ownerOP,
     AbstractMemberMetaData mmd)

Constructor.

Parameters:

ownerOP - The ObjectProvider for this set.

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

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

initialiseDelegate

protected void initialiseDelegate()

Convenience method to set up the delegate respecting any comparator specified in MetaData.

getValue

public Object getValue()

Accessor for the unwrapped value that we are wrapping.

Specified by:

getValue in interface SCO

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

isLoaded

public boolean isLoaded()

Method to return if the SCO has its contents loaded. Returns true.

Specified by:

isLoaded in interface SCOContainer

Returns:

Whether it is loaded

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

Parameters:

element - The element

fieldNumber - Number of field in the element

value - New value for this field

getFieldName

public String getFieldName()

Accessor for the field name.

Specified by:

getFieldName in interface SCO

Returns:

The field name

getOwner

public Object getOwner()

Accessor for the owner object.

Specified by:

getOwner in interface SCO

Returns:

The owner object

unsetOwner

public void unsetOwner()

Method to unset the owner and field information.

Specified by:

unsetOwner in interface SCO

makeDirty

public void makeDirty()

Utility to mark the object as dirty

detachCopy

public Object detachCopy(FetchPlanState state)

Method to return a detached copy of the container. Recurses through the elements so that they are likewise detached.

Specified by:

detachCopy in interface SCO

Parameters:

state - State for detachment process

Returns:

The detached container

attachCopy

public void attachCopy(Object value)

Method to return an attached copy of the passed (detached) value. The returned attached copy is a SCO wrapper. Goes through the existing elements in the store for this owner field and removes ones no longer present, and adds new elements. All elements in the (detached) value are attached.

Specified by:

attachCopy in interface SCO

Parameters:

value - The new (collection) value

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 PersistenceCapable objects. In contrast to Object.clone(), this method must not throw a CloneNotSupportedException.

Specified by:

clone in interface SCO

Overrides:

clone in class Object

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

Specified by:

contains in interface SCOMtoN

Overrides:

contains in class AbstractCollection

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

Overrides:

containsAll in class AbstractCollection

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

Overrides:

equals in class Object

Parameters:

o - The object to compare against.

Returns:

Whether this object is the same.

hashCode

public int hashCode()

Hashcode operator.

Specified by:

hashCode in interface Collection

Overrides:

hashCode in class Object

Returns:

The Hash code.

isEmpty

public boolean isEmpty()

Accessor for whether the Collection is empty.

Specified by:

isEmpty in interface Collection

Overrides:

isEmpty in class AbstractCollection

Returns:

Whether it is empty.

iterator

public Iterator iterator()

Accessor for an iterator for the Collection.

Specified by:

iterator in interface Iterable

Specified by:

iterator in interface Collection

Specified by:

iterator in class AbstractCollection

Returns:

The iterator

peek

public Object peek()

Method to peek at the next element in the Queue.

Specified by:

peek in interface Queue

Returns:

The element

size

public int size()

Accessor for the size of the Collection.

Specified by:

size in interface Collection

Specified by:

size in class AbstractCollection

Returns:

The size

toArray

public Object[] toArray()

Method to return the Collection as an array.

Specified by:

toArray in interface Collection

Overrides:

toArray in class AbstractCollection

Returns:

The array

toArray

public Object[] toArray(Object[] a)

Method to return the Collection as an array.

Specified by:

toArray in interface Collection

Overrides:

toArray in class AbstractCollection

Parameters:

a - The array to write the results to

Returns:

The array

add

public boolean add(Object element)

Method to add an element to the Collection.

Specified by:

add in interface Collection

Specified by:

add in interface Queue

Overrides:

add in class AbstractQueue

Parameters:

element - The element to add

Returns:

Whether it was added successfully.

addAll

public boolean addAll(Collection elements)

Method to add a collection of elements.

Specified by:

addAll in interface Collection

Overrides:

addAll in class AbstractQueue

Parameters:

elements - 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

Overrides:

clear in class AbstractQueue

offer

public boolean offer(Object element)

Method to offer an element to the Queue.

Specified by:

offer in interface Queue

Parameters:

element - The element to offer

Returns:

Whether it was added successfully.

poll

public Object poll()

Method to poll the next element in the Queue.

Specified by:

poll in interface Queue

Returns:

The element (now removed)

remove

public boolean remove(Object element)

Method to remove an element from the List

Specified by:

remove in interface Collection

Overrides:

remove in class AbstractCollection

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 List

Specified by:

remove in interface SCOCollection

Parameters:

element - The Element to remove

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

Overrides:

removeAll in class AbstractCollection

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

Overrides:

retainAll in class AbstractCollection

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.

Returns:

the replaced object

Throws:

ObjectStreamException