org.datanucleus.sco.backed
Class Collection

java.lang.Object
  extended by java.util.AbstractCollection
      extended by org.datanucleus.sco.simple.Collection
          extended by org.datanucleus.sco.backed.Collection
All Implemented Interfaces:
java.io.Serializable, java.lang.Cloneable, java.lang.Iterable, java.util.Collection, SCO, SCOCollection, SCOContainer, SCOMtoN

public class Collection
extends Collection

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
protected  boolean allowNulls
           
protected  CollectionStore backingStore
           
protected  boolean isCacheLoaded
           
protected  boolean queued
           
protected  java.util.ArrayList queuedOperations
           
protected  boolean useCache
           
 
Fields inherited from class org.datanucleus.sco.simple.Collection
delegate, fieldName, fieldNumber, LOCALISER, owner, ownerSM
 
Constructor Summary
Collection(StateManager ownerSM, java.lang.String fieldName)
          Constructor.
 
Method Summary
 boolean add(java.lang.Object element)
          Method to add an element to the Collection.
 boolean addAll(java.util.Collection c)
          Method to add a collection of elements.
protected  void addQueuedOperation(QueuedOperation op)
          Convenience method to add a queued operation to the operations we perform at commit.
 void clear()
          Method to clear the Collection.
 java.lang.Object clone()
          Creates and returns a copy of this object.
 boolean contains(java.lang.Object element)
          Accessor for whether an element is contained in the Collection.
 boolean containsAll(java.util.Collection c)
          Accessor for whether a collection of elements are contained here.
 boolean equals(java.lang.Object o)
          Equality operator.
 void flush()
          Method to flush the changes to the datastore when operating in queued mode.
 java.lang.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(java.lang.Object o, boolean forInsert, boolean forUpdate)
          Method to initialise the SCO from an existing value.
 boolean isEmpty()
          Accessor for whether the Collection is empty.
 boolean isLoaded()
          Method to return if the SCO has its contents loaded.
 java.util.Iterator 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.
 boolean remove(java.lang.Object element)
          Method to remove an element from the Collection.
 boolean remove(java.lang.Object element, boolean allowCascadeDelete)
          Method to remove an element from the collection, and observe the flag for whether to allow cascade delete.
 boolean removeAll(java.util.Collection c)
          Method to remove a Collection of elements.
 boolean retainAll(java.util.Collection c)
          Method to retain a Collection of elements (and remove all others).
 int size()
          Accessor for the size of the Collection.
 java.lang.Object[] toArray()
          Method to return the Collection as an array.
 java.lang.Object[] toArray(java.lang.Object[] a)
          Method to return the Collection as an array.
 java.lang.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(java.lang.Object element, int fieldNumber, java.lang.Object value)
          Method to update an embedded element in this collection.
protected  java.lang.Object writeReplace()
          The writeReplace method is called when ObjectOutputStream is preparing to write the object to the stream.
 
Methods inherited from class org.datanucleus.sco.simple.Collection
attachCopy, detachCopy, getFieldName, getOwner, makeDirty
 
Methods inherited from class java.lang.Object
finalize, getClass, notify, notifyAll, wait, wait, wait
 

Field Detail

backingStore

protected transient CollectionStore backingStore

allowNulls

protected transient boolean allowNulls

useCache

protected transient boolean useCache

isCacheLoaded

protected transient boolean isCacheLoaded

queued

protected transient boolean queued

queuedOperations

protected transient java.util.ArrayList queuedOperations
Constructor Detail

Collection

public Collection(StateManager ownerSM,
                  java.lang.String fieldName)
Constructor.

Parameters:
ownerSM - The State Manager for this collection.
fieldName - Name of the field
Method Detail

initialise

public void initialise(java.lang.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 Collection
Parameters:
o - The object to set from
forInsert - Whether the object needs inserting in the datastore with this value
forUpdate - Whether to update the object in 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 Collection

getValue

public java.lang.Object getValue()
Accessor for the unwrapped value that we are wrapping.

Specified by:
getValue in interface SCO
Overrides:
getValue in class Collection
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 Collection

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 Collection
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 Collection

addQueuedOperation

protected void addQueuedOperation(QueuedOperation op)
Convenience method to add a queued operation to the operations we perform at commit.

Parameters:
op - The operation

updateEmbeddedElement

public void updateEmbeddedElement(java.lang.Object element,
                                  int fieldNumber,
                                  java.lang.Object value)
Method to update an embedded element in this collection.

Specified by:
updateEmbeddedElement in interface SCOCollection
Overrides:
updateEmbeddedElement in class Collection
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 state manager and backing store information.

Specified by:
unsetOwner in interface SCO
Overrides:
unsetOwner in class Collection

clone

public java.lang.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 Collection
Returns:
A clone of the object

contains

public boolean contains(java.lang.Object element)
Accessor for whether an element is contained in the Collection.

Specified by:
contains in interface java.util.Collection
Specified by:
contains in interface SCOMtoN
Overrides:
contains in class Collection
Parameters:
element - The element
Returns:
Whether the element is contained here

containsAll

public boolean containsAll(java.util.Collection c)
Accessor for whether a collection of elements are contained here.

Specified by:
containsAll in interface java.util.Collection
Overrides:
containsAll in class Collection
Parameters:
c - The collection of elements.
Returns:
Whether they are contained.

equals

public boolean equals(java.lang.Object o)
Equality operator.

Specified by:
equals in interface java.util.Collection
Overrides:
equals in class Collection
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 java.util.Collection
Overrides:
hashCode in class Collection
Returns:
The Hash code.

isEmpty

public boolean isEmpty()
Accessor for whether the Collection is empty.

Specified by:
isEmpty in interface java.util.Collection
Overrides:
isEmpty in class Collection
Returns:
Whether it is empty.

iterator

public java.util.Iterator iterator()
Accessor for an iterator for the Collection.

Specified by:
iterator in interface java.lang.Iterable
Specified by:
iterator in interface java.util.Collection
Overrides:
iterator in class Collection
Returns:
The iterator

size

public int size()
Accessor for the size of the Collection.

Specified by:
size in interface java.util.Collection
Overrides:
size in class Collection
Returns:
The size

toArray

public java.lang.Object[] toArray()
Method to return the Collection as an array.

Specified by:
toArray in interface java.util.Collection
Overrides:
toArray in class Collection
Returns:
The array

toArray

public java.lang.Object[] toArray(java.lang.Object[] a)
Method to return the Collection as an array.

Specified by:
toArray in interface java.util.Collection
Overrides:
toArray in class Collection
Parameters:
a - The array to write the results to
Returns:
The array

toString

public java.lang.String toString()
Method to return the Collection as a String.

Overrides:
toString in class java.util.AbstractCollection
Returns:
The string form

add

public boolean add(java.lang.Object element)
Method to add an element to the Collection.

Specified by:
add in interface java.util.Collection
Overrides:
add in class Collection
Parameters:
element - The element to add
Returns:
Whether it was added successfully.

addAll

public boolean addAll(java.util.Collection c)
Method to add a collection of elements.

Specified by:
addAll in interface java.util.Collection
Overrides:
addAll in class Collection
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 java.util.Collection
Overrides:
clear in class Collection

remove

public boolean remove(java.lang.Object element)
Method to remove an element from the Collection.

Specified by:
remove in interface java.util.Collection
Overrides:
remove in class Collection
Parameters:
element - The Element to remove
Returns:
Whether it was removed successfully.

remove

public boolean remove(java.lang.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 Collection
Parameters:
element - The element
allowCascadeDelete - Whether to allow cascade delete
Returns:
Whether it was removed successfully.

removeAll

public boolean removeAll(java.util.Collection c)
Method to remove a Collection of elements.

Specified by:
removeAll in interface java.util.Collection
Overrides:
removeAll in class Collection
Parameters:
c - The collection to remove
Returns:
Whether they were removed successfully.

retainAll

public boolean retainAll(java.util.Collection c)
Method to retain a Collection of elements (and remove all others).

Specified by:
retainAll in interface java.util.Collection
Overrides:
retainAll in class Collection
Parameters:
c - The collection to retain
Returns:
Whether they were retained successfully.

writeReplace

protected java.lang.Object writeReplace()
                                 throws java.io.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
Returns:
the replaced object
Throws:
java.io.ObjectStreamException


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