java.lang.Object
- org.apache.commons.collections.collection.AbstractCollectionDecorator
- - org.apache.commons.collections.set.AbstractSetDecorator
  - - org.apache.commons.collections.set.AbstractSerializableSetDecorator
    - - org.apache.commons.collections.set.ListOrderedSet

All Implemented Interfaces:

Serializable, Iterable, Collection, Set
```
public class ListOrderedSet
extends AbstractSerializableSetDecorator
implements Set
```
Decorates another Set to ensure that the order of addition is retained and used by the iterator.
If an object is added to the set for a second time, it will remain in the original position in the iteration. The order can be observed from the set via the iterator or toArray methods.
The ListOrderedSet also has various useful direct methods. These include many from List, such as get(int), remove(int) and indexOf(int). An unmodifiable List view of the set can be obtained via asList().
This class cannot implement the List interface directly as various interface methods (notably equals/hashCode) are incompatable with a set.
This class is Serializable from Commons Collections 3.1.

Since:

Commons Collections 3.0

Version:

$Revision: 646777 $ $Date: 2008-04-10 14:33:15 +0200 (Thu, 10 Apr 2008) $

Author:

Stephen Colebourne, Henning P. Schmiedehausen

See Also:

Serialized Form

Field Summary

Fields
Modifier and Type Field Description

protected List setOrder
Internal list to hold the sequence of objects
- Fields inherited from class org.apache.commons.collections.collection.AbstractCollectionDecorator
  collection

Constructor Summary

Constructors
Modifier	Constructor	Description
	`ListOrderedSet()`	Constructs a new empty `ListOrderedSet` using a `HashSet` and an `ArrayList` internally.
`protected`	`ListOrderedSet(Set set)`	Constructor that wraps (not copies).
`protected`	`ListOrderedSet(Set set, List list)`	Constructor that wraps (not copies) the Set and specifies the list to use.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`void`	`add(int index, Object object)`
`boolean`	`add(Object object)`
`boolean`	`addAll(int index, Collection coll)`
`boolean`	`addAll(Collection coll)`
`List`	`asList()`	Gets an unmodifiable view of the order of the Set.
`void`	`clear()`
`static ListOrderedSet`	`decorate(List list)`	Factory method to create an ordered set using the supplied list to retain order.
`static ListOrderedSet`	`decorate(Set set)`	Factory method to create an ordered set.
`static ListOrderedSet`	`decorate(Set set, List list)`	Factory method to create an ordered set specifying the list and set to use.
`Object`	`get(int index)`
`int`	`indexOf(Object object)`
`Iterator`	`iterator()`
`Object`	`remove(int index)`
`boolean`	`remove(Object object)`
`boolean`	`removeAll(Collection coll)`
`boolean`	`retainAll(Collection coll)`
`Object[]`	`toArray()`
`Object[]`	`toArray(Object[] a)`
`String`	`toString()`	Uses the underlying List's toString so that order is achieved.

Methods inherited from class org.apache.commons.collections.set.AbstractSetDecorator
getSet

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

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

Methods inherited from interface java.util.Collection
parallelStream, removeIf, stream, toArray

Methods inherited from interface java.lang.Iterable
forEach

Methods inherited from interface java.util.Set
contains, containsAll, equals, hashCode, isEmpty, size, spliterator

- Field Detail
  - setOrder
```
protected final List setOrder
```
    Internal list to hold the sequence of objects
- Constructor Detail
  - ListOrderedSet
```
public ListOrderedSet()
```
    Constructs a new empty ListOrderedSet using a HashSet and an ArrayList internally.
    
    Since:
    
    Commons Collections 3.1
  - ListOrderedSet
```
protected ListOrderedSet(Set set)
```
    Constructor that wraps (not copies).
    
    Parameters:
    
    set - the set to decorate, must not be null
    
    Throws:
    
    IllegalArgumentException - if set is null
  - ListOrderedSet
```
protected ListOrderedSet(Set set,
                         List list)
```
    Constructor that wraps (not copies) the Set and specifies the list 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 ListOrderedSet decorate(Set set,
                                      List list)
```
    Factory method to create an ordered set specifying the list and set to use.
    The list and set must both be empty.
    
    Parameters:
    
    set - the set to decorate, must be empty and not null
    
    list - the list to decorate, must be empty and not null
    
    Throws:
    
    IllegalArgumentException - if set or list is null
    
    IllegalArgumentException - if either the set or list is not empty
    
    Since:
    
    Commons Collections 3.1
  - decorate
```
public static ListOrderedSet decorate(Set set)
```
    Factory method to create an ordered set.
    An ArrayList is used to retain order.
    
    Parameters:
    
    set - the set to decorate, must not be null
    
    Throws:
    
    IllegalArgumentException - if set is null
  - decorate
```
public static ListOrderedSet decorate(List list)
```
    Factory method to create an ordered set using the supplied list to retain order.
    A HashSet is used for the set behaviour.
    NOTE: If the list contains duplicates, the duplicates are removed, altering the specified list.
    
    Parameters:
    
    list - the list to decorate, must not be null
    
    Throws:
    
    IllegalArgumentException - if list is null
  - asList
```
public List asList()
```
    Gets an unmodifiable view of the order of the Set.
    
    Returns:
    
    an unmodifiable list view
  - clear
```
public void clear()
```
    Specified by:
    
    clear in interface Collection
    
    Specified by:
    
    clear in interface Set
    
    Overrides:
    
    clear in class AbstractCollectionDecorator
  - iterator
```
public Iterator iterator()
```
    Specified by:
    
    iterator in interface Collection
    
    Specified by:
    
    iterator in interface Iterable
    
    Specified by:
    
    iterator in interface Set
    
    Overrides:
    
    iterator in class AbstractCollectionDecorator
  - add
```
public boolean add(Object object)
```
    Specified by:
    
    add in interface Collection
    
    Specified by:
    
    add in interface Set
    
    Overrides:
    
    add in class AbstractCollectionDecorator
  - addAll
```
public boolean addAll(Collection coll)
```
    Specified by:
    
    addAll in interface Collection
    
    Specified by:
    
    addAll in interface Set
    
    Overrides:
    
    addAll in class AbstractCollectionDecorator
  - remove
```
public boolean remove(Object object)
```
    Specified by:
    
    remove in interface Collection
    
    Specified by:
    
    remove in interface Set
    
    Overrides:
    
    remove in class AbstractCollectionDecorator
  - removeAll
```
public boolean removeAll(Collection coll)
```
    Specified by:
    
    removeAll in interface Collection
    
    Specified by:
    
    removeAll in interface Set
    
    Overrides:
    
    removeAll in class AbstractCollectionDecorator
  - retainAll
```
public boolean retainAll(Collection coll)
```
    Specified by:
    
    retainAll in interface Collection
    
    Specified by:
    
    retainAll in interface Set
    
    Overrides:
    
    retainAll in class AbstractCollectionDecorator
  - toArray
```
public Object[] toArray()
```
    Specified by:
    
    toArray in interface Collection
    
    Specified by:
    
    toArray in interface Set
    
    Overrides:
    
    toArray in class AbstractCollectionDecorator
  - toArray
```
public Object[] toArray(Object[] a)
```
    Specified by:
    
    toArray in interface Collection
    
    Specified by:
    
    toArray in interface Set
    
    Overrides:
    
    toArray in class AbstractCollectionDecorator
  - get
```
public Object get(int index)
```
  - indexOf
```
public int indexOf(Object object)
```
  - add
```
public void add(int index,
                Object object)
```
  - addAll
```
public boolean addAll(int index,
                      Collection coll)
```
  - remove
```
public Object remove(int index)
```
  - toString
```
public String toString()
```
    Uses the underlying List's toString so that order is achieved. This means that the decorated Set's toString is not used, so any custom toStrings will be ignored.
    
    Overrides:
    
    toString in class AbstractCollectionDecorator

Class ListOrderedSet

Field Summary

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

Constructor Summary

Method Summary

Methods inherited from class org.apache.commons.collections.set.AbstractSetDecorator

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

Methods inherited from class java.lang.Object

Methods inherited from interface java.util.Collection

Methods inherited from interface java.lang.Iterable

Methods inherited from interface java.util.Set

Field Detail

setOrder

Constructor Detail

ListOrderedSet

ListOrderedSet

ListOrderedSet

Method Detail

decorate

decorate

decorate

asList

clear

iterator

add

addAll

remove

removeAll

retainAll

toArray

toArray

get

indexOf

add

addAll

remove

toString