IdentityHashSet

java.lang.Object
- java.util.AbstractCollection<E>
- - java.util.AbstractSet<E>
  - - org.jboss.msc.service.IdentityHashSet<E>

Type Parameters:

E - the element type

All Implemented Interfaces:

java.io.Serializable, java.lang.Cloneable, java.lang.Iterable<E>, java.util.Collection<E>, java.util.Set<E>
```
class IdentityHashSet<E>
extends java.util.AbstractSet<E>
implements java.util.Set<E>, java.lang.Cloneable, java.io.Serializable
```
An identity based hash set. A number of properties apply to this set. It compares only using object identity, it supports null entries, it allocates little more than a single object array, and it can be copied quickly. If the copy-ctor is passed another IdentityHashSet, or clone is called on this set, the shallow copy can be performed using little more than a single array copy. Note: It is very important to use a smaller load factor than you normally would for HashSet, since the implementation is open-addressed with linear probing. With a 50% load-factor a get is expected to return in only 2 probes. However, a 90% load-factor is expected to return in around 50 probes.

Nested Class Summary

Nested Classes
Modifier and Type Class and Description

private class IdentityHashSet.IdentityHashSetIterator

Nested Classes
Modifier and Type	Class and Description
`private class`	`IdentityHashSet.IdentityHashSetIterator`

Field Summary

Fields
Modifier and Type	Field and Description
`private static int`	`DEFAULT_CAPACITY` Same default as HashMap, must be a power of 2
`private static float`	`DEFAULT_LOAD_FACTOR` 67%, just like IdentityHashMap
`private float`	`loadFactor` The user defined load factor which defines when to resize
`private static int`	`MAXIMUM_CAPACITY` MAX_INT - 1
`private int`	`modCount` Counter used to detect changes made outside of an iterator
`private static long`	`serialVersionUID` Serialization ID
`private int`	`size` The current number of key-value pairs
`private java.lang.Object[]`	`table` The open-addressed table
`private int`	`threshold` The next resize

Constructor Summary

Constructors
Constructor and Description
`IdentityHashSet()`
`IdentityHashSet(int initialCapacity)`
`IdentityHashSet(int initialCapacity, float loadFactor)`
`IdentityHashSet(java.util.Set<? extends E> set)`

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`boolean`	`add(E entry)`
`boolean`	`addAll(java.util.Collection<? extends E> collection)`
`void`	`clear()`
`IdentityHashSet<E>`	`clone()`
`boolean`	`contains(java.lang.Object entry)`
`private static int`	`hash(java.lang.Object o)`
`private static int`	`index(int hashCode, int length)`
`private void`	`init(int initialCapacity, float loadFactor)`
`boolean`	`isEmpty()`
`java.util.Iterator<E>`	`iterator()`
`private int`	`nextIndex(int index, int length)`
`void`	`printDebugStats()`
`private void`	`putForCreate(E entry)`
`private void`	`readObject(java.io.ObjectInputStream s)`
`private void`	`relocate(int start)`
`boolean`	`remove(java.lang.Object o)`
`private void`	`resize(int from)`
`int`	`size()`
`E[]`	`toArray(E[] target, int offs, int len)` Warning: this will crap out if the set contains a `null`.
`<T> T[]`	`toScatteredArray(T[] dummy)` Advanced method that returns a copy of the internal table.
`private void`	`writeObject(java.io.ObjectOutputStream s)`

Methods inherited from class java.util.AbstractSet
equals, hashCode, removeAll

Methods inherited from class java.util.AbstractCollection
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
containsAll, equals, hashCode, removeAll, retainAll, spliterator, toArray, toArray

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

Methods inherited from interface java.lang.Iterable
forEach

- Field Detail
  - serialVersionUID
```
private static final long serialVersionUID
```
    Serialization ID
    
    See Also:
    
    Constant Field Values
  - DEFAULT_CAPACITY
```
private static final int DEFAULT_CAPACITY
```
    Same default as HashMap, must be a power of 2
    
    See Also:
    
    Constant Field Values
  - MAXIMUM_CAPACITY
```
private static final int MAXIMUM_CAPACITY
```
    MAX_INT - 1
    
    See Also:
    
    Constant Field Values
  - DEFAULT_LOAD_FACTOR
```
private static final float DEFAULT_LOAD_FACTOR
```
    67%, just like IdentityHashMap
    
    See Also:
    
    Constant Field Values
  - table
```
private transient java.lang.Object[] table
```
    The open-addressed table
  - size
```
private transient int size
```
    The current number of key-value pairs
  - threshold
```
private transient int threshold
```
    The next resize
  - loadFactor
```
private final float loadFactor
```
    The user defined load factor which defines when to resize
  - modCount
```
private transient int modCount
```
    Counter used to detect changes made outside of an iterator
- Constructor Detail
  - IdentityHashSet
```
public IdentityHashSet(int initialCapacity,
                       float loadFactor)
```
  - IdentityHashSet
```
public IdentityHashSet(java.util.Set<? extends E> set)
```
  - IdentityHashSet
```
public IdentityHashSet(int initialCapacity)
```
  - IdentityHashSet
```
public IdentityHashSet()
```
- Method Detail
  - init
```
private void init(int initialCapacity,
                  float loadFactor)
```
  - hash
```
private static int hash(java.lang.Object o)
```
  - nextIndex
```
private int nextIndex(int index,
                      int length)
```
  - index
```
private static int index(int hashCode,
                         int length)
```
  - size
```
public int size()
```
    Specified by:
    
    size in interface java.util.Collection<E>
    
    Specified by:
    
    size in interface java.util.Set<E>
    
    Specified by:
    
    size in class java.util.AbstractCollection<E>
  - isEmpty
```
public boolean isEmpty()
```
    Specified by:
    
    isEmpty in interface java.util.Collection<E>
    
    Specified by:
    
    isEmpty in interface java.util.Set<E>
    
    Overrides:
    
    isEmpty in class java.util.AbstractCollection<E>
  - contains
```
public boolean contains(java.lang.Object entry)
```
    Specified by:
    
    contains in interface java.util.Collection<E>
    
    Specified by:
    
    contains in interface java.util.Set<E>
    
    Overrides:
    
    contains in class java.util.AbstractCollection<E>
  - add
```
public boolean add(E entry)
```
    Specified by:
    
    add in interface java.util.Collection<E>
    
    Specified by:
    
    add in interface java.util.Set<E>
    
    Overrides:
    
    add in class java.util.AbstractCollection<E>
  - resize
```
private void resize(int from)
```
  - addAll
```
public boolean addAll(java.util.Collection<? extends E> collection)
```
    Specified by:
    
    addAll in interface java.util.Collection<E>
    
    Specified by:
    
    addAll in interface java.util.Set<E>
    
    Overrides:
    
    addAll in class java.util.AbstractCollection<E>
  - remove
```
public boolean remove(java.lang.Object o)
```
    Specified by:
    
    remove in interface java.util.Collection<E>
    
    Specified by:
    
    remove in interface java.util.Set<E>
    
    Overrides:
    
    remove in class java.util.AbstractCollection<E>
  - relocate
```
private void relocate(int start)
```
  - clear
```
public void clear()
```
    Specified by:
    
    clear in interface java.util.Collection<E>
    
    Specified by:
    
    clear in interface java.util.Set<E>
    
    Overrides:
    
    clear in class java.util.AbstractCollection<E>
  - clone
```
public IdentityHashSet<E> clone()
```
    Overrides:
    
    clone in class java.lang.Object
  - toScatteredArray
```
public <T> T[] toScatteredArray(T[] dummy)
```
    Advanced method that returns a copy of the internal table. The resulting array will contain nulls at random places that must be skipped. In addition, it will not operate correctly if a null was inserted into the set. Use at your own risk....
    
    Parameters:
    
    dummy - the input array
    
    Returns:
    
    an array containing elements in this set along with randomly placed nulls,
  - toArray
```
public E[] toArray(E[] target,
                   int offs,
                   int len)
```
    Warning: this will crap out if the set contains a null.
    
    Parameters:
    
    target - the target to write to
    
    offs - the offset into the target
    
    len - the length to write
    
    Returns:
    
    the target array
  - printDebugStats
```
public void printDebugStats()
```
  - readObject
```
private void readObject(java.io.ObjectInputStream s)
                 throws java.io.IOException,
                        java.lang.ClassNotFoundException
```
    Throws:
    
    java.io.IOException
    
    java.lang.ClassNotFoundException
  - putForCreate
```
private void putForCreate(E entry)
```
  - writeObject
```
private void writeObject(java.io.ObjectOutputStream s)
                  throws java.io.IOException
```
    Throws:
    
    java.io.IOException
  - iterator
```
public java.util.Iterator<E> iterator()
```
    Specified by:
    
    iterator in interface java.lang.Iterable<E>
    
    Specified by:
    
    iterator in interface java.util.Collection<E>
    
    Specified by:
    
    iterator in interface java.util.Set<E>
    
    Specified by:
    
    iterator in class java.util.AbstractCollection<E>

Class IdentityHashSet<E>

Nested Class Summary

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.util.AbstractSet

Methods inherited from class java.util.AbstractCollection

Methods inherited from class java.lang.Object

Methods inherited from interface java.util.Set

Methods inherited from interface java.util.Collection

Methods inherited from interface java.lang.Iterable

Field Detail

serialVersionUID

DEFAULT_CAPACITY

MAXIMUM_CAPACITY

DEFAULT_LOAD_FACTOR

table

size

threshold

loadFactor

modCount

Constructor Detail

IdentityHashSet

IdentityHashSet

IdentityHashSet

IdentityHashSet

Method Detail

init

hash

nextIndex

index

size

isEmpty

contains

add

resize

addAll

remove

relocate

clear

clone

toScatteredArray

toArray

printDebugStats

readObject

putForCreate

writeObject

iterator