Class AbstractCollectionDecorator<E>
- Type Parameters:
E- the type of the elements in the collection
- All Implemented Interfaces:
Serializable,Iterable<E>,Collection<E>
- Direct Known Subclasses:
AbstractBagDecorator,AbstractDualBidiMap.View,AbstractListDecorator,AbstractMultiSetDecorator,AbstractQueueDecorator,AbstractSetDecorator,IndexedCollection,PredicatedCollection,TransformedCollection,UnmodifiableBoundedCollection,UnmodifiableCollection
Collection to provide additional behavior.
Each method call made on this Collection is forwarded to the
decorated Collection. This class is used as a framework on which
to build to extensions such as synchronized and unmodifiable behavior. The
main advantage of decoration is that one decorator can wrap any implementation
of Collection, whereas sub-classing requires a new class to be
written for each implementation.
This implementation does not perform any special processing with
iterator(). Instead it simply returns the value from the
wrapped collection. This may be undesirable, for example if you are trying
to write an unmodifiable implementation it might provide a loophole.
This implementation does not forward the hashCode and equals methods through
to the backing object, but relies on Object's implementation. This is necessary
to preserve the symmetry of equals. Custom definitions of equality are usually
based on an interface, such as Set or List, so that the implementation of equals
can cast the object being tested for equality to the custom interface.
AbstractCollectionDecorator does not implement such custom interfaces directly;
they are implemented only in subclasses. Therefore, forwarding equals would break
symmetry, as the forwarding object might consider itself equal to the object being
tested, but the reverse could not be true. This behavior is consistent with the
JDK's collection wrappers, such as Collections.unmodifiableCollection(Collection).
Use an interface-specific subclass of AbstractCollectionDecorator, such as
AbstractListDecorator, to preserve equality behavior, or override equals directly.
- Since:
- 3.0
- See Also:
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Constructor Summary
ConstructorsModifierConstructorDescriptionprotectedConstructor only used in deserialization, do not use otherwise.protectedAbstractCollectionDecorator(Collection<E> collection) Constructor that wraps (not copies). -
Method Summary
Modifier and TypeMethodDescriptionbooleanbooleanaddAll(Collection<? extends E> coll) voidclear()booleanbooleancontainsAll(Collection<?> coll) protected Collection<E> Gets the collection being decorated.booleanisEmpty()iterator()booleanbooleanremoveAll(Collection<?> coll) booleanbooleanretainAll(Collection<?> coll) protected voidsetCollection(Collection<E> collection) Sets the collection being decorated.intsize()Object[]toArray()<T> T[]toArray(T[] object) toString()Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, waitMethods inherited from interface java.util.Collection
equals, hashCode, parallelStream, spliterator, stream
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Constructor Details
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AbstractCollectionDecorator
protected AbstractCollectionDecorator()Constructor only used in deserialization, do not use otherwise.- Since:
- 3.1
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AbstractCollectionDecorator
Constructor that wraps (not copies).- Parameters:
collection- the collection to decorate, must not be null- Throws:
NullPointerException- if the collection is null
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Method Details
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add
- Specified by:
addin interfaceCollection<E>
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addAll
- Specified by:
addAllin interfaceCollection<E>
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clear
- Specified by:
clearin interfaceCollection<E>
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contains
- Specified by:
containsin interfaceCollection<E>
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containsAll
- Specified by:
containsAllin interfaceCollection<E>
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decorated
Gets the collection being decorated. All access to the decorated collection goes via this method.- Returns:
- the decorated collection
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isEmpty
- Specified by:
isEmptyin interfaceCollection<E>
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iterator
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remove
- Specified by:
removein interfaceCollection<E>
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removeAll
- Specified by:
removeAllin interfaceCollection<E>
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removeIf
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retainAll
- Specified by:
retainAllin interfaceCollection<E>
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setCollection
Sets the collection being decorated.NOTE: this method should only be used during deserialization
- Parameters:
collection- the decorated collection
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size
- Specified by:
sizein interfaceCollection<E>
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toArray
- Specified by:
toArrayin interfaceCollection<E>
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toArray
- Specified by:
toArrayin interfaceCollection<E>
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toString
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