org.apache.commons.collections.list
public class SetUniqueList extends AbstractSerializableListDecorator
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: Commons Collections 3.0
Version: $Revision: 155406 $ $Date: 2005-02-26 12:55:26 +0000 (Sat, 26 Feb 2005) $
Field Summary | |
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protected Set | set
Internal Set to maintain uniqueness. |
Constructor Summary | |
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protected | SetUniqueList(List list, Set set)
Constructor that wraps (not copies) the List and specifies the set to use.
|
Method Summary | |
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boolean | add(Object object)
Adds an element to the list if it is not already present.
|
void | add(int index, Object object)
Adds an element to a specific index in the list if it is not already present.
|
boolean | addAll(Collection coll)
Adds an element to the end of the list if it is not already present.
|
boolean | addAll(int index, Collection coll)
Adds a collection of objects to the end of the list avoiding duplicates.
|
Set | asSet()
Gets an unmodifiable view as a Set.
|
void | clear() |
boolean | contains(Object object) |
boolean | containsAll(Collection coll) |
static SetUniqueList | decorate(List list)
Factory method to create a SetList using the supplied list to retain order.
|
Iterator | iterator() |
ListIterator | listIterator() |
ListIterator | listIterator(int index) |
boolean | remove(Object object) |
Object | remove(int index) |
boolean | removeAll(Collection coll) |
boolean | retainAll(Collection coll) |
Object | set(int index, Object object)
Sets the value at the specified index avoiding duplicates.
|
List | subList(int fromIndex, int toIndex) |
The set and list must both be correctly initialised to the same elements.
Parameters: set the set to decorate, must not be null list the list to decorate, must not be null
Throws: IllegalArgumentException if set or list is null
(Violation)
The List
interface requires that this method returns
true
always. However this class may return false
because of the Set
behaviour.
Parameters: object the object to add
Returns: true if object was added
(Violation)
The List
interface makes the assumption that the element is
always inserted. This may not happen with this implementation.
Parameters: index the index to insert at object the object to add
(Violation)
The List
interface makes the assumption that the element is
always inserted. This may not happen with this implementation.
Parameters: coll the collection to add
Only elements that are not already in this list will be added, and duplicates from the specified collection will be ignored.
(Violation)
The List
interface makes the assumption that the elements
are always inserted. This may not happen with this implementation.
Parameters: index the index to insert at coll the collection to add in iterator order
Returns: true if this collection changed
Returns: an unmodifiable set view
If the list contains duplicates, these are removed (first indexed one kept).
A HashSet
is used for the set behaviour.
Parameters: list the list to decorate, must not be null
Throws: IllegalArgumentException if list is null
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.
Parameters: index the index to insert at object the object to set
Returns: the previous object