dsto.dfc.collections
Class IdentityHashSet

java.lang.Object
  java.util.AbstractCollection<E>
      java.util.AbstractSet
          dsto.dfc.collections.IdentityHashSet

All Implemented Interfaces:

Serializable, Cloneable, Iterable, Collection, Set

public class IdentityHashSet
extends AbstractSet
implements Set, Cloneable, Serializable

Exactly like HashSet except uses an IdentityHashMap as backing, thus comparing objects using == instead of equals ().

Version:

$Revision$

Author:

mpp

See Also:

Serialized Form

Constructor Summary

IdentityHashSet()
Constructs a new, empty set; the backing IdentityHashMap instance has default capacity and load factor, which is 0.75.

IdentityHashSet(Collection c)
Constructs a new set containing the elements in the specified collection.

IdentityHashSet(int initialCapacity)
Constructs a new, empty set; the backing IdentityHashMap instance has the specified initial capacity and default load factor, which is 0.75.

IdentityHashSet(int initialCapacity, float loadFactor)
Constructs a new, empty set; the backing IdentityHashMap instance has the specified initial capacity and the specified load factor.

Method Summary

boolean	add(Object o) Adds the specified element to this set if it is not already present.
void	clear() Removes all of the elements from this set.
Object	clone() Returns a shallow copy of this identityHashSet instance: the elements themselves are not cloned.
boolean	contains(Object o) Returns true if this set contains the specified element.
boolean	isEmpty() Returns true if this set contains no elements.
Iterator	iterator() Returns an iterator over the elements in this set.
boolean	remove(Object o) Removes the given element from this set if it is present.
int	size() Returns the number of elements in this set (its cardinality).

Methods inherited from class java.util.AbstractSet

equals, hashCode, removeAll

Methods inherited from class java.util.AbstractCollection

addAll, containsAll, retainAll, toArray, toArray, toString

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.util.Set

addAll, containsAll, equals, hashCode, removeAll, retainAll, toArray, toArray

Constructor Detail

IdentityHashSet

public IdentityHashSet()

Constructs a new, empty set; the backing IdentityHashMap instance has default capacity and load factor, which is 0.75.

IdentityHashSet

public IdentityHashSet(Collection c)

Constructs a new set containing the elements in the specified collection. The capacity of the backing IdentityHashMap instance is twice the size of the specified collection or eleven (whichever is greater), and the default load factor (which is 0.75) is used.

Parameters:

c - the collection whose elements are to be placed into this set.

IdentityHashSet

public IdentityHashSet(int initialCapacity,
                       float loadFactor)

Constructs a new, empty set; the backing IdentityHashMap instance has the specified initial capacity and the specified load factor.

Parameters:

initialCapacity - the initial capacity of the hash map.

loadFactor - the load factor of the hash map.

Throws:

IllegalArgumentException - if the initial capacity is less than zero, or if the load factor is nonpositive.

IdentityHashSet

public IdentityHashSet(int initialCapacity)

Constructs a new, empty set; the backing IdentityHashMap instance has the specified initial capacity and default load factor, which is 0.75.

Parameters:

initialCapacity - the initial capacity of the hash table.

Throws:

IllegalArgumentException - if the initial capacity is less than zero.

Method Detail

iterator

public Iterator iterator()

Returns an iterator over the elements in this set. The elements are returned in no particular order.

Specified by:

iterator in interface Iterable

Specified by:

iterator in interface Collection

Specified by:

iterator in interface Set

Specified by:

iterator in class AbstractCollection

Returns:

an Iterator over the elements in this set.

size

public int size()

Returns the number of elements in this set (its cardinality).

Specified by:

size in interface Collection

Specified by:

size in interface Set

Specified by:

size in class AbstractCollection

Returns:

the number of elements in this set (its cardinality).

isEmpty

public boolean isEmpty()

Returns true if this set contains no elements.

Specified by:

isEmpty in interface Collection

Specified by:

isEmpty in interface Set

Overrides:

isEmpty in class AbstractCollection

Returns:

true if this set contains no elements.

contains

public boolean contains(Object o)

Returns true if this set contains the specified element.

Specified by:

contains in interface Collection

Specified by:

contains in interface Set

Overrides:

contains in class AbstractCollection

Parameters:

o - element whose presence in this set is to be tested.

Returns:

true if this set contains the specified element.

add

public boolean add(Object o)

Adds the specified element to this set if it is not already present.

Specified by:

add in interface Collection

Specified by:

add in interface Set

Overrides:

add in class AbstractCollection

Parameters:

o - element to be added to this set.

Returns:

true if the set did not already contain the specified element.

remove

public boolean remove(Object o)

Removes the given element from this set if it is present.

Specified by:

remove in interface Collection

Specified by:

remove in interface Set

Overrides:

remove in class AbstractCollection

Parameters:

o - object to be removed from this set, if present.

Returns:

true if the set contained the specified element.

clear

public void clear()

Removes all of the elements from this set.

Specified by:

clear in interface Collection

Specified by:

clear in interface Set

Overrides:

clear in class AbstractCollection

clone

public Object clone()

Returns a shallow copy of this identityHashSet instance: the elements themselves are not cloned.

Overrides:

clone in class Object

Returns:

a shallow copy of this set.