org.datanucleus.store.types.sco.backed
Class Stack

java.lang.Object
  java.util.AbstractCollection<E>
      java.util.AbstractList<E>
          java.util.Vector<E>
              java.util.Stack
                  org.datanucleus.store.types.sco.simple.Stack
                      org.datanucleus.store.types.sco.backed.Stack

All Implemented Interfaces:

Serializable, Cloneable, Iterable, Collection, List, RandomAccess, SCO, SCOCollection, SCOContainer, SCOList

public class Stack
extends Stack

A mutable second-class Stack object. This class extends Stack, 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

protected boolean	allowNulls
protected ListStore	backingStore
protected boolean	isCacheLoaded
protected OperationQueue<ListStore>	operationQueue
protected boolean	queued
protected boolean	useCache

Fields inherited from class org.datanucleus.store.types.sco.simple.Stack

delegate, fieldName, fieldNumber, LOCALISER, ownerSM

Fields inherited from class java.util.Vector

capacityIncrement, elementCount, elementData

Fields inherited from class java.util.AbstractList

modCount

Constructor Summary

Stack(ObjectProvider ownerSM, String fieldName)
Constructor, using the StateManager of the "owner" and the field name.

Method Summary

void	add(int index, Object element) Method to add an element to a position in the Stack
boolean	add(Object element) Method to add an element to the Stack
boolean	addAll(Collection elements) Method to add a Collection to the Stack
boolean	addAll(int index, Collection elements) Method to add a Collection to a position in the Stack
void	addElement(Object element) Method to add an element to the Stack
protected void	addQueuedOperation(QueuedOperation<? super ListStore> op) Convenience method to add a queued operation to the operations we perform at commit.
void	clear() Method to clear the Stack
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	empty() Accessor for whether the Stack is empty.
boolean	equals(Object o) Equality operator.
void	flush() Method to flush the changes to the datastore when operating in queued mode.
Object	get(int index) Method to retrieve an element no.
Object	getValue() Accessor for the unwrapped value that we are wrapping.
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 Stack 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() 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	peek() Method to retrieve the element at the top of the stack.
Object	pop() Method to remove the top element in the stack and return it.
Object	push(Object element) Method to push an element onto the stack and return it.
Object	remove(int index) Method to remove an element from the Stack
boolean	remove(Object element) Method to remove an element from the Stack
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 objects from the Stack
void	removeAllElements() Method to remove all elements from the Stack.
boolean	removeElement(Object element) Method to remove an element from the Stack
void	removeElementAt(int index) Method to remove an element from the Stack
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 Stack
Object	set(int index, Object element, boolean allowDependentField) Wrapper addition that allows turning off of the dependent-field checks when doing the position setting.
void	setElementAt(Object element, int index) Method to set the element at a position in the Stack
int	size() Accessor for the size of the Stack.
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.sco.simple.Stack

attachCopy, detachCopy, getFieldName, getOwner, hashCode, makeDirty

Methods inherited from class java.util.Stack

search

Methods inherited from class java.util.Vector

capacity, containsAll, copyInto, elementAt, elements, ensureCapacity, firstElement, indexOf, insertElementAt, lastElement, lastIndexOf, removeRange, setSize, toString, trimToSize

Methods inherited from class java.lang.Object

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

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

operationQueue

protected transient OperationQueue<ListStore> operationQueue

Constructor Detail

Stack

public Stack(ObjectProvider ownerSM,
             String fieldName)

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

Parameters:

ownerSM - The owner StateManager

fieldName - The name of the field of the SCO.

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 Stack

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 Stack

getValue

public Object getValue()

Accessor for the unwrapped value that we are wrapping.

Specified by:

getValue in interface SCO

Overrides:

getValue in class Stack

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 Stack

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 Stack

Returns:

Whether it is loaded

loadFromStore

protected void loadFromStore()

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

flush

public void flush()

Method to flush the changes to the datastore when operating in queued mode. Does nothing in "direct" mode.

Specified by:

flush in interface SCOContainer

Overrides:

flush in class Stack

addQueuedOperation

protected void addQueuedOperation(QueuedOperation<? super ListStore> op)

Convenience method to add a queued operation to the operations we perform at commit.

Parameters:

op - The operation

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 Stack

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 Stack

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 Stack

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 List

Overrides:

contains in class Stack

Parameters:

element - The element

Returns:

Whether it is contained

empty

public boolean empty()

Accessor for whether the Stack is empty.

Overrides:

empty in class Stack

Returns:

Whether it is empty.

equals

public boolean equals(Object o)

Equality operator.

Specified by:

equals in interface Collection

Specified by:

equals in interface List

Overrides:

equals in class Stack

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 Stack

Parameters:

index - The item to retrieve

Returns:

The element at that position.

indexOf

public int indexOf(Object element)

Method to the position of an element.

Specified by:

indexOf in interface List

Overrides:

indexOf in class Stack

Parameters:

element - The element.

Returns:

The position.

isEmpty

public boolean isEmpty()

Accessor for whether the Stack is empty.

Specified by:

isEmpty in interface Collection

Specified by:

isEmpty in interface List

Overrides:

isEmpty in class Stack

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 List

Overrides:

iterator in class Stack

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 Stack

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 Stack

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 Stack

Parameters:

element - The element

Returns:

The last position of this element in the List.

peek

public Object peek()

Method to retrieve the element at the top of the stack.

Overrides:

peek in class Stack

Returns:

The element at the top of the stack

size

public int size()

Accessor for the size of the Stack.

Specified by:

size in interface Collection

Specified by:

size in interface List

Overrides:

size in class Stack

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 Stack

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 Stack

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 Stack

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 Stack

Specified by:

add in interface List

Overrides:

add in class Stack

Parameters:

index - The position

element - The new element

add

public boolean add(Object element)

Method to add an element to the Stack

Specified by:

add in interface Collection

Specified by:

add in interface List

Overrides:

add in class Stack

Parameters:

element - The new element

Returns:

Whether it was added ok.

addElement

public void addElement(Object element)

Method to add an element to the Stack

Overrides:

addElement in class Stack

Parameters:

element - The new element

addAll

public boolean addAll(Collection elements)

Method to add a Collection to the Stack

Specified by:

addAll in interface Collection

Specified by:

addAll in interface List

Overrides:

addAll in class Stack

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 Stack

Specified by:

addAll in interface List

Overrides:

addAll in class Stack

Parameters:

index - Position to insert the collection.

elements - The collection

Returns:

Whether it was added ok.

clear

public void clear()

Method to clear the Stack

Specified by:

clear in interface Collection

Specified by:

clear in interface List

Overrides:

clear in class Stack

pop

public Object pop()

Method to remove the top element in the stack and return it.

Overrides:

pop in class Stack

Returns:

The top element that was in the Stack (now removed).

push

public Object push(Object element)

Method to push an element onto the stack and return it.

Overrides:

push in class Stack

Parameters:

element - The element to push onto the stack.

Returns:

The element that was pushed onto the Stack

remove

public boolean remove(Object element)

Method to remove an element from the Stack

Specified by:

remove in interface Collection

Specified by:

remove in interface List

Overrides:

remove in class Stack

Parameters:

element - The element

Returns:

Whether the element was removed

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 Stack

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 objects from the Stack

Specified by:

removeAll in interface Collection

Specified by:

removeAll in interface List

Overrides:

removeAll in class Stack

Parameters:

elements - The Collection

Returns:

Whether the collection of elements were removed

removeElement

public boolean removeElement(Object element)

Method to remove an element from the Stack

Overrides:

removeElement in class Stack

Parameters:

element - The element

Returns:

Whether the element was removed

remove

public Object remove(int index)

Method to remove an element from the Stack

Specified by:

remove in interface List

Overrides:

remove in class Stack

Parameters:

index - The element position.

Returns:

The object that was removed

removeElementAt

public void removeElementAt(int index)

Method to remove an element from the Stack

Overrides:

removeElementAt in class Stack

Parameters:

index - The element position.

removeAllElements

public void removeAllElements()

Method to remove all elements from the Stack. Same as clear().

Overrides:

removeAllElements in class Stack

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 Stack

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 Stack

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 Stack

Specified by:

set in interface List

Overrides:

set in class Stack

Parameters:

index - The position

element - The new element

Returns:

The element previously at that position

setElementAt

public void setElementAt(Object element,
                         int index)

Method to set the element at a position in the Stack

Overrides:

setElementAt in class Stack

Parameters:

element - The new element

index - The 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 Stack

Returns:

the replaced object

Throws:

ObjectStreamException