Package org.datanucleus.store.types.wrappers.backed

Class Set<E>

  • All Implemented Interfaces:
    Serializable, Cloneable, Iterable<E>, Collection<E>, Set<E>, SCO<Set<E>>, SCOCollection<Set<E>,​E>, SCOContainer<Set<E>>, BackedSCO
    public class Set<E>
extends Set<E>
implements BackedSCO
    A mutable second-class Set object. This class extends Set, 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 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

      • Set

        public Set​(DNStateManager ownerSM,
           AbstractMemberMetaData mmd,
           boolean allowNulls,
           SetStore backingStore)
        Constructor allowing the specification of the backing store to be used.
        Parameters:
        ownerSM - StateManager for the owning object
        mmd - Metadata for the member
        allowNulls - Whether nulls are allowed
        backingStore - The backing store

    • Method Detail

      • initialise

        public void initialise​(Set<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<E>
        Overrides:
        initialise in class Set<E>
        Parameters:
        newValue - New value (to wrap)
        oldValue - Old value (to use in deciding what needs deleting etc)

      • initialise

        public void initialise​(Set c)
        Method to initialise the SCO from an existing value.
        Specified by:
        initialise in interface SCO<E>
        Overrides:
        initialise in class Set<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<E>
        Overrides:
        initialise in class Set<E>

      • getValue

        public Set getValue()
        Accessor for the unwrapped value that we are wrapping.
        Specified by:
        getValue in interface SCO<E>
        Overrides:
        getValue in class Set<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<E>
        Overrides:
        load in class Set<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 BackedSCO
        Specified by:
        isLoaded in interface SCOContainer<E>
        Overrides:
        isLoaded in class Set<E>
        Returns:
        Whether it is loaded

      • loadFromStore

        protected void loadFromStore()
        Method to load all elements from the "backing store" where appropriate.

      • 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<Set<E>,​E>
        Overrides:
        updateEmbeddedElement in class Set<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<E>
        Overrides:
        unsetOwner in class Set<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<E>
        Overrides:
        clone in class Set<E>
        Returns:
        A clone of the object

      • contains

        public boolean contains​(Object element)
        Description copied from class: Set
        Accessor for whether an element is contained in the Collection.
        Specified by:
        contains in interface Collection<E>
        Specified by:
        contains in interface Set<E>
        Overrides:
        contains in class Set<E>
        Parameters:
        element - The element
        Returns:
        Whether the element is contained here

      • containsAll

        public boolean containsAll​(Collection c)
        Description copied from class: Set
        Accessor for whether a collection of elements are contained here.
        Specified by:
        containsAll in interface Collection<E>
        Specified by:
        containsAll in interface Set<E>
        Overrides:
        containsAll in class Set<E>
        Parameters:
        c - The collection of elements.
        Returns:
        Whether they are contained.

      • equals

        public boolean equals​(Object o)
        Description copied from class: Set
        Equality operator.
        Specified by:
        equals in interface Collection<E>
        Specified by:
        equals in interface Set<E>
        Overrides:
        equals in class Set<E>
        Parameters:
        o - The object to compare against.
        Returns:
        Whether this object is the same.

      • hashCode

        public int hashCode()
        Description copied from class: Set
        Hashcode operator.
        Specified by:
        hashCode in interface Collection<E>
        Specified by:
        hashCode in interface Set<E>
        Overrides:
        hashCode in class Set<E>
        Returns:
        The Hash code.

      • isEmpty

        public boolean isEmpty()
        Description copied from class: Set
        Accessor for whether the Collection is empty.
        Specified by:
        isEmpty in interface Collection<E>
        Specified by:
        isEmpty in interface Set<E>
        Overrides:
        isEmpty in class Set<E>
        Returns:
        Whether it is empty.

      • size

        public int size()
        Description copied from class: Set
        Accessor for the size of the Collection.
        Specified by:
        size in interface Collection<E>
        Specified by:
        size in interface Set<E>
        Overrides:
        size in class Set<E>
        Returns:
        The size

      • toArray

        public Object[] toArray()
        Description copied from class: Set
        Method to return the Collection as an array.
        Specified by:
        toArray in interface Collection<E>
        Specified by:
        toArray in interface Set<E>
        Overrides:
        toArray in class Set<E>
        Returns:
        The array

      • toArray

        public Object[] toArray​(Object[] a)
        Description copied from class: Set
        Method to return the Collection as an array.
        Specified by:
        toArray in interface Collection<E>
        Specified by:
        toArray in interface Set<E>
        Overrides:
        toArray in class Set<E>
        Parameters:
        a - The array to write the results to
        Returns:
        The array

      • add

        public boolean add​(E element)
        Description copied from class: Set
        Method to add an element to the Collection.
        Specified by:
        add in interface Collection<E>
        Specified by:
        add in interface Set<E>
        Overrides:
        add in class Set<E>
        Parameters:
        element - The element to add
        Returns:
        Whether it was added successfully.

      • addAll

        public boolean addAll​(Collection elements)
        Description copied from class: Set
        Method to add a collection of elements.
        Specified by:
        addAll in interface Collection<E>
        Specified by:
        addAll in interface Set<E>
        Overrides:
        addAll in class Set<E>
        Parameters:
        elements - The collection of elements to add.
        Returns:
        Whether they were added successfully.

      • clear

        public void clear()
        Description copied from class: Set
        Method to clear the Collection.
        Specified by:
        clear in interface Collection<E>
        Specified by:
        clear in interface Set<E>
        Overrides:
        clear in class Set<E>

      • remove

        public boolean remove​(Object element)
        Description copied from class: Set
        Method to remove (the first occurrence of) an element from the collection
        Specified by:
        remove in interface Collection<E>
        Specified by:
        remove in interface Set<E>
        Overrides:
        remove in class Set<E>
        Parameters:
        element - The Element to remove
        Returns:
        Whether it was removed successfully.

      • remove

        public boolean remove​(Object element,
                      boolean allowCascadeDelete)
        Description copied from class: Set
        Method to remove (the first occurrence of) an element from the collection
        Specified by:
        remove in interface SCOCollection<Set<E>,​E>
        Overrides:
        remove in class Set<E>
        Parameters:
        element - The Element to remove
        allowCascadeDelete - Whether to cascade delete
        Returns:
        Whether it was removed successfully.

      • removeAll

        public boolean removeAll​(Collection elements)
        Description copied from class: Set
        Method to remove a Collection of elements.
        Specified by:
        removeAll in interface Collection<E>
        Specified by:
        removeAll in interface Set<E>
        Overrides:
        removeAll in class Set<E>
        Parameters:
        elements - The collection to remove
        Returns:
        Whether they were removed successfully.

      • retainAll

        public boolean retainAll​(Collection c)
        Description copied from class: Set
        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 Set<E>
        Parameters:
        c - The collection to retain
        Returns:
        Whether they were retained successfully.

      • writeReplace

        protected Object writeReplace()
                       throws ObjectStreamException
        Description copied from class: Set
        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 Set<E>
        Returns:
        the replaced object
        Throws:
        ObjectStreamException - if an error occurs