Class SetUniqueList<E>
- Type Parameters:
E- the type of the elements in the list.
- All Implemented Interfaces:
Serializable,Iterable<E>,Collection<E>,List<E>
List to ensure that no duplicates are present much
like a Set.
The List interface makes certain assumptions/requirements. This
implementation breaks these in certain ways, but this is merely the result of
rejecting duplicates. Each violation is explained in the method, but it
should not affect you. Bear in mind that Sets require immutable objects to
function correctly.
The ListOrderedSet
class provides an alternative approach, by wrapping an existing Set and
retaining insertion order in the iterator.
This class is Serializable from Commons Collections 3.1.
- Since:
- 3.0
- See Also:
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Constructor Summary
ConstructorsModifierConstructorDescriptionprotectedSetUniqueList(List<E> list, Set<E> set) Constructor that wraps (not copies) the List and specifies the set to use. -
Method Summary
Modifier and TypeMethodDescriptionvoidAdds an element to a specific index in the list if it is not already present.booleanAdds an element to the list if it is not already present.booleanaddAll(int index, Collection<? extends E> coll) Adds a collection of objects a specific index in the list avoiding duplicates.booleanaddAll(Collection<? extends E> coll) Adds a collection of objects to the end of the list avoiding duplicates.asSet()Gets an unmodifiable view as a Set.voidclear()booleanbooleancontainsAll(Collection<?> coll) createSetBasedOnList(Set<E> set, List<E> list) iterator()listIterator(int index) remove(int index) booleanbooleanremoveAll(Collection<?> coll) booleanbooleanretainAll(Collection<?> coll) Sets the value at the specified index avoiding duplicates.static <E> SetUniqueList<E> setUniqueList(List<E> list) Factory method to create a SetList using the supplied list to retain order.subList(int fromIndex, int toIndex) Methods inherited from class org.apache.commons.collections4.list.AbstractListDecorator
decorated, equals, get, hashCode, indexOf, lastIndexOfMethods inherited from class org.apache.commons.collections4.collection.AbstractCollectionDecorator
isEmpty, setCollection, size, toArray, toArray, toStringMethods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, waitMethods inherited from interface java.util.Collection
parallelStream, streamMethods inherited from interface java.util.List
isEmpty, replaceAll, size, sort, spliterator, toArray, toArray
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Constructor Details
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SetUniqueList
Constructor that wraps (not copies) the List and specifies the set to use.The set and list must both be correctly initialized to the same elements.
- Parameters:
list- the list to decorate, must not be nullset- the set to decorate, must not be null- Throws:
NullPointerException- if set or list is null
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Method Details
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setUniqueList
Factory method to create a SetList using the supplied list to retain order.If the list contains duplicates, these are removed (first indexed one kept). A
HashSetis used for the set behavior.- Type Parameters:
E- the element type- Parameters:
list- the list to decorate, must not be null- Returns:
- a new
SetUniqueList - Throws:
NullPointerException- if list is null- Since:
- 4.0
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add
Adds an element to the list if it is not already present.(Violation) The
Listinterface requires that this method returnstruealways. However, this class may returnfalsebecause of theSetbehavior.- Specified by:
addin interfaceCollection<E>- Specified by:
addin interfaceList<E>- Overrides:
addin classAbstractCollectionDecorator<E>- Parameters:
object- the object to add- Returns:
- true if object was added
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add
Adds an element to a specific index in the list if it is not already present.(Violation) The
Listinterface makes the assumption that the element is always inserted. This may not happen with this implementation. -
addAll
Adds a collection of objects to the end of the list avoiding duplicates.Only elements that are not already in this list will be added, and duplicates from the specified collection will be ignored.
(Violation) The
Listinterface makes the assumption that the elements are always inserted. This may not happen with this implementation.- Specified by:
addAllin interfaceCollection<E>- Specified by:
addAllin interfaceList<E>- Overrides:
addAllin classAbstractCollectionDecorator<E>- Parameters:
coll- the collection to add in iterator order- Returns:
- true if this collection changed
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addAll
Adds a collection of objects a specific index in the list avoiding duplicates.Only elements that are not already in this list will be added, and duplicates from the specified collection will be ignored.
(Violation) The
Listinterface makes the assumption that the elements are always inserted. This may not happen with this implementation. -
asSet
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clear
- Specified by:
clearin interfaceCollection<E>- Specified by:
clearin interfaceList<E>- Overrides:
clearin classAbstractCollectionDecorator<E>
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contains
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containsAll
- Specified by:
containsAllin interfaceCollection<E>- Specified by:
containsAllin interfaceList<E>- Overrides:
containsAllin classAbstractCollectionDecorator<E>
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createSetBasedOnList
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iterator
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listIterator
- Specified by:
listIteratorin interfaceList<E>- Overrides:
listIteratorin classAbstractListDecorator<E>
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listIterator
- Specified by:
listIteratorin interfaceList<E>- Overrides:
listIteratorin classAbstractListDecorator<E>
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remove
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remove
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removeAll
- Specified by:
removeAllin interfaceCollection<E>- Specified by:
removeAllin interfaceList<E>- Overrides:
removeAllin classAbstractCollectionDecorator<E>
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removeIf
- Specified by:
removeIfin interfaceCollection<E>- Overrides:
removeIfin classAbstractCollectionDecorator<E>- Since:
- 4.4
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retainAll
This implementation iterates over the elements of this list, checking each element in turn to see if it's contained in
coll. If it's not contained, it's removed from this list. As a consequence, it is advised to use a collection type forcollthat provides a fast (for example O(1)) implementation ofCollection.contains(Object).- Specified by:
retainAllin interfaceCollection<E>- Specified by:
retainAllin interfaceList<E>- Overrides:
retainAllin classAbstractCollectionDecorator<E>
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set
Sets the value at the specified index avoiding duplicates.The object is set into the specified index. Afterwards, any previous duplicate is removed. If the object is not already in the list then a normal set occurs. If it is present, then the old version is removed.
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subList
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