org.apache.commons.collections4.set
Class MapBackedSet<E,V>

java.lang.Object
  extended by org.apache.commons.collections4.set.MapBackedSet<E,V>
All Implemented Interfaces:
Serializable, Iterable<E>, Collection<E>, Set<E>

public final class MapBackedSet<E,V>
extends Object
implements Set<E>, Serializable

Decorates a Map to obtain Set behaviour.

This class is used to create a Set with the same properties as the key set of any map. Thus, a ReferenceSet can be created by wrapping a ReferenceMap in an instance of this class.

Most map implementation can be used to create a set by passing in dummy values. Exceptions include BidiMap implementations, as they require unique values.

Since:
3.1
Version:
$Id: MapBackedSet.java 1479406 2013-05-05 22:02:01Z tn $
See Also:
Serialized Form

Method Summary
 boolean add(E obj)
           
 boolean addAll(Collection<? extends E> coll)
           
 void clear()
           
 boolean contains(Object obj)
           
 boolean containsAll(Collection<?> coll)
           
 boolean equals(Object obj)
           
 int hashCode()
           
 boolean isEmpty()
           
 Iterator<E> iterator()
           
static
<E,V> MapBackedSet<E,V>
mapBackedSet(Map<E,? super V> map)
          Factory method to create a set from a map.
static
<E,V> MapBackedSet<E,V>
mapBackedSet(Map<E,? super V> map, V dummyValue)
          Factory method to create a set from a map.
 boolean remove(Object obj)
           
 boolean removeAll(Collection<?> coll)
           
 boolean retainAll(Collection<?> coll)
           
 int size()
           
 Object[] toArray()
           
<T> T[]
toArray(T[] array)
           
 
Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait
 

Method Detail

mapBackedSet

public static <E,V> MapBackedSet<E,V> mapBackedSet(Map<E,? super V> map)
Factory method to create a set from a map.

Type Parameters:
E - the element type
V - the dummy value type in the map
Parameters:
map - the map to decorate, must not be null
Returns:
a new map backed set
Throws:
IllegalArgumentException - if set is null
Since:
4.0

mapBackedSet

public static <E,V> MapBackedSet<E,V> mapBackedSet(Map<E,? super V> map,
                                                   V dummyValue)
Factory method to create a set from a map.

Type Parameters:
E - the element type
V - the dummy value type in the map
Parameters:
map - the map to decorate, must not be null
dummyValue - the dummy value to use
Returns:
a new map backed set
Throws:
IllegalArgumentException - if map is null
Since:
4.0

size

public int size()
Specified by:
size in interface Collection<E>
Specified by:
size in interface Set<E>

isEmpty

public boolean isEmpty()
Specified by:
isEmpty in interface Collection<E>
Specified by:
isEmpty in interface Set<E>

iterator

public Iterator<E> iterator()
Specified by:
iterator in interface Iterable<E>
Specified by:
iterator in interface Collection<E>
Specified by:
iterator in interface Set<E>

contains

public boolean contains(Object obj)
Specified by:
contains in interface Collection<E>
Specified by:
contains in interface Set<E>

containsAll

public boolean containsAll(Collection<?> coll)
Specified by:
containsAll in interface Collection<E>
Specified by:
containsAll in interface Set<E>

add

public boolean add(E obj)
Specified by:
add in interface Collection<E>
Specified by:
add in interface Set<E>

addAll

public boolean addAll(Collection<? extends E> coll)
Specified by:
addAll in interface Collection<E>
Specified by:
addAll in interface Set<E>

remove

public boolean remove(Object obj)
Specified by:
remove in interface Collection<E>
Specified by:
remove in interface Set<E>

removeAll

public boolean removeAll(Collection<?> coll)
Specified by:
removeAll in interface Collection<E>
Specified by:
removeAll in interface Set<E>

retainAll

public boolean retainAll(Collection<?> coll)
Specified by:
retainAll in interface Collection<E>
Specified by:
retainAll in interface Set<E>

clear

public void clear()
Specified by:
clear in interface Collection<E>
Specified by:
clear in interface Set<E>

toArray

public Object[] toArray()
Specified by:
toArray in interface Collection<E>
Specified by:
toArray in interface Set<E>

toArray

public <T> T[] toArray(T[] array)
Specified by:
toArray in interface Collection<E>
Specified by:
toArray in interface Set<E>

equals

public boolean equals(Object obj)
Specified by:
equals in interface Collection<E>
Specified by:
equals in interface Set<E>
Overrides:
equals in class Object

hashCode

public int hashCode()
Specified by:
hashCode in interface Collection<E>
Specified by:
hashCode in interface Set<E>
Overrides:
hashCode in class Object


Copyright © 2001–2013 The Apache Software Foundation. All rights reserved.