SetUniqueList (Apache Commons Collections 3.2.2 API)

java.lang.Object
- org.apache.commons.collections.collection.AbstractCollectionDecorator
- - org.apache.commons.collections.list.AbstractListDecorator
  - - org.apache.commons.collections.list.AbstractSerializableListDecorator
    - - org.apache.commons.collections.list.SetUniqueList

All Implemented Interfaces:

Serializable, Iterable, Collection, List
```
public class SetUniqueList
extends AbstractSerializableListDecorator
```
Decorates a 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: 972404 $ $Date: 2015-11-08 22:35:53 +0100 (Sun, 08 Nov 2015) $

Author:

Matthew Hawthorne, Stephen Colebourne, Tom Dunham

See Also:
Serialized Form

Field Summary

Fields
Modifier and Type Field and Description

protected Set set
Internal Set to maintain uniqueness.
- Fields inherited from class org.apache.commons.collections.collection.AbstractCollectionDecorator
  collection

Fields
Modifier and Type	Field and Description
`protected Set`	`set` Internal Set to maintain uniqueness.

Constructor Summary

Constructors
Modifier Constructor and Description

protected SetUniqueList(List list, Set set)
Constructor that wraps (not copies) the List and specifies the set to use.

Constructors
Modifier	Constructor and Description
`protected`	`SetUniqueList(List list, Set set)` Constructor that wraps (not copies) the List and specifies the set to use.

Method Summary

Methods
Modifier and Type	Method and Description
`void`	`add(int index, Object object)` Adds an element to a specific index in the list if it is not already present.
`boolean`	`add(Object object)` Adds an element to 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 a specific index in the list avoiding duplicates.
`Set`	`asSet()` Gets an unmodifiable view as a Set.
`void`	`clear()`
`boolean`	`contains(Object object)`
`boolean`	`containsAll(Collection coll)`
`protected Set`	`createSetBasedOnList(Set set, List list)` Create a new `Set` with the same type as the provided `set` and populate it with all elements of `list`.
`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)`
`Object`	`remove(int index)`
`boolean`	`remove(Object object)`
`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)`

Methods inherited from class org.apache.commons.collections.list.AbstractListDecorator
get, getList, indexOf, lastIndexOf

Methods inherited from class org.apache.commons.collections.collection.AbstractCollectionDecorator
equals, getCollection, hashCode, isEmpty, size, toArray, toArray, toString

Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.util.List
equals, hashCode, isEmpty, size, toArray, toArray

- Field Detail
  - set
```
protected final Set set
```
    Internal Set to maintain uniqueness.
- Constructor Detail
  - SetUniqueList
```
protected SetUniqueList(List list,
             Set set)
```
    Constructor that wraps (not copies) the List and specifies the set to use.
    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
- Method Detail
  - decorate
```
public static SetUniqueList decorate(List list)
```
    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 HashSet is used for the set behaviour.
    
    Parameters:
    list - the list to decorate, must not be null
    
    Throws:
    
    IllegalArgumentException - if list is null
  - asSet
```
public Set asSet()
```
    Gets an unmodifiable view as a Set.
    
    Returns:
    an unmodifiable set view
  - add
```
public boolean add(Object object)
```
    Adds an element to the list if it is not already present.
    (Violation) The List interface requires that this method returns true always. However this class may return false because of the Set behaviour.
    
    Specified by:
    
    add in interface Collection
    
    Specified by:
    
    add in interface List
    
    Overrides:
    
    add in class AbstractCollectionDecorator
    
    Parameters:
    object - the object to add
    
    Returns:
    true if object was added
  - add
```
public void add(int index,
       Object object)
```
    Adds an element to a specific index in the list if it is not already present.
    (Violation) The List interface makes the assumption that the element is always inserted. This may not happen with this implementation.
    
    Specified by:
    
    add in interface List
    
    Overrides:
    
    add in class AbstractListDecorator
    
    Parameters:
    index - the index to insert at
    object - the object to add
  - addAll
```
public boolean addAll(Collection coll)
```
    Adds an element to the end of the list if it is not already present.
    (Violation) The List interface makes the assumption that the element is always inserted. This may not happen with this implementation.
    
    Specified by:
    
    addAll in interface Collection
    
    Specified by:
    
    addAll in interface List
    
    Overrides:
    
    addAll in class AbstractCollectionDecorator
    
    Parameters:
    coll - the collection to add
  - addAll
```
public boolean addAll(int index,
             Collection coll)
```
    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 List interface makes the assumption that the elements are always inserted. This may not happen with this implementation.
    
    Specified by:
    
    addAll in interface List
    
    Overrides:
    
    addAll in class AbstractListDecorator
    
    Parameters:
    index - the index to insert at
    coll - the collection to add in iterator order
    
    Returns:
    true if this collection changed
  - set
```
public Object set(int index,
         Object object)
```
    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.
    
    Specified by:
    
    set in interface List
    
    Overrides:
    
    set in class AbstractListDecorator
    
    Parameters:
    index - the index to insert at
    object - the object to set
    
    Returns:
    the previous object
  - remove
```
public boolean remove(Object object)
```
    Specified by:
    
    remove in interface Collection
    
    Specified by:
    
    remove in interface List
    
    Overrides:
    
    remove in class AbstractCollectionDecorator
  - remove
```
public Object remove(int index)
```
    Specified by:
    
    remove in interface List
    
    Overrides:
    
    remove in class AbstractListDecorator
  - removeAll
```
public boolean removeAll(Collection coll)
```
    Specified by:
    
    removeAll in interface Collection
    
    Specified by:
    
    removeAll in interface List
    
    Overrides:
    
    removeAll in class AbstractCollectionDecorator
  - retainAll
```
public boolean retainAll(Collection coll)
```
    Specified by:
    
    retainAll in interface Collection
    
    Specified by:
    
    retainAll in interface List
    
    Overrides:
    
    retainAll in class AbstractCollectionDecorator
  - clear
```
public void clear()
```
    Specified by:
    
    clear in interface Collection
    
    Specified by:
    
    clear in interface List
    
    Overrides:
    
    clear in class AbstractCollectionDecorator
  - contains
```
public boolean contains(Object object)
```
    Specified by:
    
    contains in interface Collection
    
    Specified by:
    
    contains in interface List
    
    Overrides:
    
    contains in class AbstractCollectionDecorator
  - containsAll
```
public boolean containsAll(Collection coll)
```
    Specified by:
    
    containsAll in interface Collection
    
    Specified by:
    
    containsAll in interface List
    
    Overrides:
    
    containsAll in class AbstractCollectionDecorator
  - iterator
```
public Iterator iterator()
```
    Specified by:
    
    iterator in interface Iterable
    
    Specified by:
    
    iterator in interface Collection
    
    Specified by:
    
    iterator in interface List
    
    Overrides:
    
    iterator in class AbstractCollectionDecorator
  - listIterator
```
public ListIterator listIterator()
```
    Specified by:
    
    listIterator in interface List
    
    Overrides:
    
    listIterator in class AbstractListDecorator
  - listIterator
```
public ListIterator listIterator(int index)
```
    Specified by:
    
    listIterator in interface List
    
    Overrides:
    
    listIterator in class AbstractListDecorator
  - subList
```
public List subList(int fromIndex,
           int toIndex)
```
    Specified by:
    
    subList in interface List
    
    Overrides:
    
    subList in class AbstractListDecorator
  - createSetBasedOnList
```
protected Set createSetBasedOnList(Set set,
                       List list)
```
    Create a new Set with the same type as the provided set and populate it with all elements of list.
    
    Parameters:
    set - the Set to be used as return type, must not be null
    list - the List to populate the Set
    
    Returns:
    a new Set populated with all elements of the provided List

Class SetUniqueList

Field Summary

Fields inherited from class org.apache.commons.collections.collection.AbstractCollectionDecorator

Constructor Summary

Method Summary

Methods inherited from class org.apache.commons.collections.list.AbstractListDecorator

Methods inherited from class org.apache.commons.collections.collection.AbstractCollectionDecorator

Methods inherited from class java.lang.Object

Methods inherited from interface java.util.List

Field Detail

set

Constructor Detail

SetUniqueList

Method Detail

decorate

asSet

add

add

addAll

addAll

set

remove

remove

removeAll

retainAll

clear

contains

containsAll

iterator

listIterator

listIterator

subList

createSetBasedOnList