org.limewire.collection
Class IdentityHashSet<E>

java.lang.Object
  java.util.AbstractCollection<E>
      java.util.AbstractSet<E>
          org.limewire.collection.IdentityHashSet<E>

All Implemented Interfaces:

Serializable, Cloneable, Iterable<E>, Collection<E>, Set<E>

public class IdentityHashSet<E>
extends AbstractSet<E>
implements Set<E>, Cloneable, Serializable

A set equivalent of IdentityHashMap.

    IdentityHashSet<String> ihs = new IdentityHashSet<String>(4);

    String s = new String("Abby");
    ihs.add(s);

    if(!ihs.add(s))
        System.out.println("Already contained ("+ s + "); contents: " + ihs);

    if(ihs.add("Abby"))
        System.out.println("Was able to add a new String(\"Abby\") since it's a separate object.");

    System.out.println("Contents: " + ihs);

    ihs.add("Bob");
    ihs.add("Chris");
    ihs.add("Dan");
    System.out.println("Size is: " + ihs.size() + " contents: " + ihs); 

    Output:
        Already contained (Abby); contents: [Abby]
        Was able to add a new String("Abby") since it's a separate object.
        Contents: [Abby, Abby]
        Size is: 5 contents: [Dan, Chris, Abby, Abby, Bob]

See Also:

Serialized Form

Constructor Summary

IdentityHashSet()
Constructs a new, empty set; the backing IdentityHashMap instance has default initial capacity (16) and load factor (0.75).

IdentityHashSet(Collection<? extends E> 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.

Method Summary

boolean	add(E 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<E>	iterator() Returns an iterator over the elements in this set.
boolean	remove(Object o) Removes the specified 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 initial capacity (16) and load factor (0.75).

IdentityHashSet

public IdentityHashSet(Collection<? extends E> c)

Constructs a new set containing the elements in the specified collection. The IdentityHashMap is created with default load factor (0.75) and an initial capacity sufficient to contain the elements in the specified collection.

Parameters:

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

Throws:

NullPointerException - if the specified collection is null.

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<E> iterator()

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

Specified by:

iterator in interface Iterable<E>

Specified by:

iterator in interface Collection<E>

Specified by:

iterator in interface Set<E>

Specified by:

iterator in class AbstractCollection<E>

Returns:

an Iterator over the elements in this set.

See Also:

ConcurrentModificationException

size

public int size()

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

Specified by:

size in interface Collection<E>

Specified by:

size in interface Set<E>

Specified by:

size in class AbstractCollection<E>

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<E>

Specified by:

isEmpty in interface Set<E>

Overrides:

isEmpty in class AbstractCollection<E>

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<E>

Specified by:

contains in interface Set<E>

Overrides:

contains in class AbstractCollection<E>

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(E o)

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

Specified by:

add in interface Collection<E>

Specified by:

add in interface Set<E>

Overrides:

add in class AbstractCollection<E>

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 specified element from this set if it is present.

Specified by:

remove in interface Collection<E>

Specified by:

remove in interface Set<E>

Overrides:

remove in class AbstractCollection<E>

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<E>

Specified by:

clear in interface Set<E>

Overrides:

clear in class AbstractCollection<E>

clone

public Object clone()
             throws CloneNotSupportedException

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.

Throws:

CloneNotSupportedException