IdentityHashtable (Red Hat JBoss Enterprise Application Platform 7.0.0.GA public API)

java.lang.Object
- java.util.Dictionary
- - com.sun.corba.se.impl.util.IdentityHashtable

```
public final class IdentityHashtable
extends Dictionary
```
IdentityHashtable is a modified copy of the 1.1.6 Hashtable class which does not rely on the hashCode() and equals() methods of the key or value; instead, it uses the System.identityHashcode() method and pointer comparison. In addition, all synchronization has been removed.

Constructor Summary

Constructors
Constructor and Description
`IdentityHashtable()` Constructs a new, empty hashtable with a default capacity and load factor.
`IdentityHashtable(int initialCapacity)` Constructs a new, empty hashtable with the specified initial capacity and default load factor.
`IdentityHashtable(int initialCapacity, float loadFactor)` Constructs a new, empty hashtable with the specified initial capacity and the specified load factor.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`void`	`clear()` Clears this hashtable so that it contains no keys.
`boolean`	`contains(Object value)` Tests if some key maps into the specified value in this hashtable.
`boolean`	`containsKey(Object key)` Tests if the specified object is a key in this hashtable.
`Enumeration`	`elements()` Returns an enumeration of the values in this hashtable.
`Object`	`get(Object key)` Returns the value to which the specified key is mapped in this hashtable.
`boolean`	`isEmpty()` Tests if this hashtable maps no keys to values.
`Enumeration`	`keys()` Returns an enumeration of the keys in this hashtable.
`Object`	`put(Object key, Object value)` Maps the specified `key` to the specified `value` in this hashtable.
`protected void`	`rehash()` Rehashes the contents of the hashtable into a hashtable with a larger capacity.
`Object`	`remove(Object key)` Removes the key (and its corresponding value) from this hashtable.
`int`	`size()` Returns the number of keys in this hashtable.
`String`	`toString()` Returns a rather long string representation of this hashtable.

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

- Constructor Detail
  - IdentityHashtable
```
public IdentityHashtable(int initialCapacity,
                         float loadFactor)
```
    Constructs a new, empty hashtable with the specified initial capacity and the specified load factor.
    
    Parameters:
    
    initialCapacity - the initial capacity of the hashtable.
    
    loadFactor - a number between 0.0 and 1.0.
    
    Throws:
    
    IllegalArgumentException - if the initial capacity is less than or equal to zero, or if the load factor is less than or equal to zero.
    
    Since:
    
    JDK1.0
  - IdentityHashtable
```
public IdentityHashtable(int initialCapacity)
```
    Constructs a new, empty hashtable with the specified initial capacity and default load factor.
    
    Parameters:
    
    initialCapacity - the initial capacity of the hashtable.
    
    Since:
    
    JDK1.0
  - IdentityHashtable
```
public IdentityHashtable()
```
    Constructs a new, empty hashtable with a default capacity and load factor.
    
    Since:
    
    JDK1.0
- Method Detail
  - size
```
public int size()
```
    Returns the number of keys in this hashtable.
    
    Specified by:
    
    size in class Dictionary
    
    Returns:
    
    the number of keys in this hashtable.
    
    Since:
    
    JDK1.0
  - isEmpty
```
public boolean isEmpty()
```
    Tests if this hashtable maps no keys to values.
    
    Specified by:
    
    isEmpty in class Dictionary
    
    Returns:
    
    true if this hashtable maps no keys to values; false otherwise.
    
    Since:
    
    JDK1.0
  - keys
```
public Enumeration keys()
```
    Returns an enumeration of the keys in this hashtable.
    
    Specified by:
    
    keys in class Dictionary
    
    Returns:
    
    an enumeration of the keys in this hashtable.
    
    Since:
    
    JDK1.0
    
    See Also:
    
    Enumeration, Hashtable.elements()
  - elements
```
public Enumeration elements()
```
    Returns an enumeration of the values in this hashtable. Use the Enumeration methods on the returned object to fetch the elements sequentially.
    
    Specified by:
    
    elements in class Dictionary
    
    Returns:
    
    an enumeration of the values in this hashtable.
    
    Since:
    
    JDK1.0
    
    See Also:
    
    Enumeration, Hashtable.keys()
  - contains
```
public boolean contains(Object value)
```
    Tests if some key maps into the specified value in this hashtable. This operation is more expensive than the containsKey method.
    
    Parameters:
    
    value - a value to search for.
    
    Returns:
    
    true if some key maps to the value argument in this hashtable; false otherwise.
    
    Throws:
    
    NullPointerException - if the value is null.
    
    Since:
    
    JDK1.0
    
    See Also:
    
    Hashtable.containsKey(java.lang.Object)
  - containsKey
```
public boolean containsKey(Object key)
```
    Tests if the specified object is a key in this hashtable.
    
    Parameters:
    
    key - possible key.
    
    Returns:
    
    true if the specified object is a key in this hashtable; false otherwise.
    
    Since:
    
    JDK1.0
    
    See Also:
    
    Hashtable.contains(java.lang.Object)
  - get
```
public Object get(Object key)
```
    Returns the value to which the specified key is mapped in this hashtable.
    
    Specified by:
    
    get in class Dictionary
    
    Parameters:
    
    key - a key in the hashtable.
    
    Returns:
    
    the value to which the key is mapped in this hashtable; null if the key is not mapped to any value in this hashtable.
    
    Since:
    
    JDK1.0
    
    See Also:
    
    Hashtable.put(java.lang.Object, java.lang.Object)
  - rehash
```
protected void rehash()
```
    Rehashes the contents of the hashtable into a hashtable with a larger capacity. This method is called automatically when the number of keys in the hashtable exceeds this hashtable's capacity and load factor.
    
    Since:
    
    JDK1.0
  - put
```
public Object put(Object key,
                  Object value)
```
    Maps the specified key to the specified value in this hashtable. Neither the key nor the value can be null.
    The value can be retrieved by calling the get method with a key that is equal to the original key.
    
    Specified by:
    
    put in class Dictionary
    
    Parameters:
    
    key - the hashtable key.
    
    value - the value.
    
    Returns:
    
    the previous value of the specified key in this hashtable, or null if it did not have one.
    
    Throws:
    
    NullPointerException - if the key or value is null.
    
    Since:
    
    JDK1.0
    
    See Also:
    
    Hashtable.get(java.lang.Object)
  - remove
```
public Object remove(Object key)
```
    Removes the key (and its corresponding value) from this hashtable. This method does nothing if the key is not in the hashtable.
    
    Specified by:
    
    remove in class Dictionary
    
    Parameters:
    
    key - the key that needs to be removed.
    
    Returns:
    
    the value to which the key had been mapped in this hashtable, or null if the key did not have a mapping.
    
    Since:
    
    JDK1.0
  - clear
```
public void clear()
```
    Clears this hashtable so that it contains no keys.
    
    Since:
    
    JDK1.0
  - toString
```
public String toString()
```
    Returns a rather long string representation of this hashtable.
    
    Overrides:
    
    toString in class Object
    
    Returns:
    
    a string representation of this hashtable.
    
    Since:
    
    JDK1.0

Class IdentityHashtable

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

IdentityHashtable

IdentityHashtable

IdentityHashtable

Method Detail

size

isEmpty

keys

elements

contains

containsKey

get

rehash

put

remove

clear

toString