Build 1.0_r1(from source)

java.util
Class Hashtable<K,V>

java.lang.Object
  extended by java.util.Dictionary<K,V>
      extended by java.util.Hashtable<K,V>
All Implemented Interfaces:
Serializable, Cloneable, Map<K,V>
Direct Known Subclasses:
Properties

public class Hashtable<K,V>
extends Dictionary<K,V>
implements Map<K,V>, Cloneable, Serializable

Hashtable associates keys with values. Keys and values cannot be null. The size of the Hashtable is the number of key/value pairs it contains. The capacity is the number of key/value pairs the Hashtable can hold. The load factor is a float value which determines how full the Hashtable gets before expanding the capacity. If the load factor of the Hashtable is exceeded, the capacity is doubled.

See Also:
Enumeration, Serializable, Object.equals(java.lang.Object), Object.hashCode(), Serialized Form

Field Summary
(package private)  int elementCount
           
(package private)  java.util.Hashtable.Entry<K,V>[] elementData
           
(package private)  int firstSlot
           
(package private)  int lastSlot
           
(package private)  int modCount
           
 
Constructor Summary
Hashtable()
          Constructs a new Hashtable using the default capacity and load factor.
Hashtable(int capacity)
          Constructs a new Hashtable using the specified capacity and the default load factor.
Hashtable(int capacity, float loadFactor)
          Constructs a new Hashtable using the specified capacity and load factor.
Hashtable(Map<? extends K,? extends V> map)
          Constructs a new instance of Hashtable containing the mappings from the specified Map.
 
Method Summary
 void clear()
          Removes all key/value pairs from this Hashtable, leaving the size zero and the capacity unchanged.
 Object clone()
          Returns a new Hashtable with the same key/value pairs, capacity and load factor.
 boolean contains(Object value)
          Returns if this Hashtable contains the specified object as the value of at least one of the key/value pairs.
 boolean containsKey(Object key)
          Returns if this Hashtable contains the specified object as a key of one of the key/value pairs.
 boolean containsValue(Object value)
          Searches this Hashtable for the specified value.
 Enumeration<V> elements()
          Returns an Enumeration on the values of this Hashtable.
 Set<Map.Entry<K,V>> entrySet()
          Returns a Set of the mappings contained in this Hashtable.
 boolean equals(Object object)
          Compares the specified object to this Hashtable and answer if they are equal.
 V get(Object key)
          Returns the value associated with the specified key in this Hashtable.
(package private)  java.util.Hashtable.Entry<K,V> getEntry(Object key)
           
 int hashCode()
          Returns an integer hash code for the receiver.
 boolean isEmpty()
          Returns if this Hashtable has no key/value pairs, a size of zero.
 Enumeration<K> keys()
          Returns an Enumeration on the keys of this Hashtable.
 Set<K> keySet()
          Returns a Set of the keys contained in this Hashtable.
 V put(K key, V value)
          Associate the specified value with the specified key in this Hashtable.
 void putAll(Map<? extends K,? extends V> map)
          Copies every mapping in the specified Map to this Hashtable.
protected  void rehash()
          Increases the capacity of this Hashtable.
 V remove(Object key)
          Remove the key/value pair with the specified key from this Hashtable.
 int size()
          Returns the number of key/value pairs in this Hashtable.
 String toString()
          Returns the string representation of this Hashtable.
 Collection<V> values()
          Returns a Collection of the values contained in this Hashtable.
 
Methods inherited from class java.lang.Object
finalize, getClass, notify, notifyAll, wait, wait, wait
 

Field Detail

elementCount

transient int elementCount

elementData

transient java.util.Hashtable.Entry<K,V>[] elementData

firstSlot

transient int firstSlot

lastSlot

transient int lastSlot

modCount

transient int modCount
Constructor Detail

Hashtable

public Hashtable()
Constructs a new Hashtable using the default capacity and load factor.


Hashtable

public Hashtable(int capacity)
Constructs a new Hashtable using the specified capacity and the default load factor.

Parameters:
capacity - the initial capacity

Hashtable

public Hashtable(int capacity,
                 float loadFactor)
Constructs a new Hashtable using the specified capacity and load factor.

Parameters:
capacity - the initial capacity
loadFactor - the initial load factor

Hashtable

public Hashtable(Map<? extends K,? extends V> map)
Constructs a new instance of Hashtable containing the mappings from the specified Map.

Parameters:
map - the mappings to add
Method Detail

clear

public void clear()
Removes all key/value pairs from this Hashtable, leaving the size zero and the capacity unchanged.

Specified by:
clear in interface Map<K,V>
See Also:
isEmpty(), size()

clone

public Object clone()
Returns a new Hashtable with the same key/value pairs, capacity and load factor.

Overrides:
clone in class Object
Returns:
a shallow copy of this Hashtable
See Also:
Cloneable

contains

public boolean contains(Object value)
Returns if this Hashtable contains the specified object as the value of at least one of the key/value pairs.

Parameters:
value - the object to look for as a value in this Hashtable
Returns:
true if object is a value in this Hashtable, false otherwise
See Also:
containsKey(java.lang.Object), Object.equals(java.lang.Object)

containsKey

public boolean containsKey(Object key)
Returns if this Hashtable contains the specified object as a key of one of the key/value pairs.

Specified by:
containsKey in interface Map<K,V>
Parameters:
key - the object to look for as a key in this Hashtable
Returns:
true if object is a key in this Hashtable, false otherwise
See Also:
contains(java.lang.Object), Object.equals(java.lang.Object)

containsValue

public boolean containsValue(Object value)
Searches this Hashtable for the specified value.

Specified by:
containsValue in interface Map<K,V>
Parameters:
value - the object to search for
Returns:
true if value is a value of this Hashtable, false otherwise

elements

public Enumeration<V> elements()
Returns an Enumeration on the values of this Hashtable. The results of the Enumeration may be affected if the contents of this Hashtable are modified.

Specified by:
elements in class Dictionary<K,V>
Returns:
an Enumeration of the values of this Hashtable
See Also:
keys(), size(), Enumeration

entrySet

public Set<Map.Entry<K,V>> entrySet()
Returns a Set of the mappings contained in this Hashtable. Each element in the set is a Map.Entry. The set is backed by this Hashtable so changes to one are reflected by the other. The set does not support adding.

Specified by:
entrySet in interface Map<K,V>
Returns:
a Set of the mappings

equals

public boolean equals(Object object)
Compares the specified object to this Hashtable and answer if they are equal. The object must be an instance of Map and contain the same key/value pairs.

Specified by:
equals in interface Map<K,V>
Overrides:
equals in class Object
Parameters:
object - the object to compare with this object
Returns:
true if the specified object is equal to this Map, false otherwise
See Also:
hashCode()

get

public V get(Object key)
Returns the value associated with the specified key in this Hashtable.

Specified by:
get in interface Map<K,V>
Specified by:
get in class Dictionary<K,V>
Parameters:
key - the key of the value returned
Returns:
the value associated with the specified key, null if the specified key does not exist
See Also:
put(K, V)

getEntry

java.util.Hashtable.Entry<K,V> getEntry(Object key)

hashCode

public int hashCode()
Returns an integer hash code for the receiver. Objects which are equal answer the same value for this method.

Specified by:
hashCode in interface Map<K,V>
Overrides:
hashCode in class Object
Returns:
the receiver's hash
See Also:
equals(java.lang.Object)

isEmpty

public boolean isEmpty()
Returns if this Hashtable has no key/value pairs, a size of zero.

Specified by:
isEmpty in interface Map<K,V>
Specified by:
isEmpty in class Dictionary<K,V>
Returns:
true if this Hashtable has no key/value pairs, false otherwise
See Also:
size()

keys

public Enumeration<K> keys()
Returns an Enumeration on the keys of this Hashtable. The results of the Enumeration may be affected if the contents of this Hashtable are modified.

Specified by:
keys in class Dictionary<K,V>
Returns:
an Enumeration of the keys of this Hashtable
See Also:
elements(), size(), Enumeration

keySet

public Set<K> keySet()
Returns a Set of the keys contained in this Hashtable. The set is backed by this Hashtable so changes to one are reflected by the other. The set does not support adding.

Specified by:
keySet in interface Map<K,V>
Returns:
a Set of the keys

put

public V put(K key,
             V value)
Associate the specified value with the specified key in this Hashtable. If the key already exists, the old value is replaced. The key and value cannot be null.

Specified by:
put in interface Map<K,V>
Specified by:
put in class Dictionary<K,V>
Parameters:
key - the key to add
value - the value to add
Returns:
the old value associated with the specified key, null if the key did not exist
See Also:
elements(), get(java.lang.Object), keys(), Object.equals(java.lang.Object)

putAll

public void putAll(Map<? extends K,? extends V> map)
Copies every mapping in the specified Map to this Hashtable.

Specified by:
putAll in interface Map<K,V>
Parameters:
map - the Map to copy mappings from

rehash

protected void rehash()
Increases the capacity of this Hashtable. This method is sent when the size of this Hashtable exceeds the load factor.


remove

public V remove(Object key)
Remove the key/value pair with the specified key from this Hashtable.

Specified by:
remove in interface Map<K,V>
Specified by:
remove in class Dictionary<K,V>
Parameters:
key - the key to remove
Returns:
the value associated with the specified key, null if the specified key did not exist
See Also:
get(java.lang.Object), put(K, V)

size

public int size()
Returns the number of key/value pairs in this Hashtable.

Specified by:
size in interface Map<K,V>
Specified by:
size in class Dictionary<K,V>
Returns:
the number of key/value pairs in this Hashtable
See Also:
elements(), keys()

toString

public String toString()
Returns the string representation of this Hashtable.

Overrides:
toString in class Object
Returns:
the string representation of this Hashtable

values

public Collection<V> values()
Returns a Collection of the values contained in this Hashtable. The collection is backed by this Hashtable so changes to one are reflected by the other. The collection does not support adding.

Specified by:
values in interface Map<K,V>
Returns:
a Collection of the values

Build 1.0_r1(from source)

Please submit a feedback, bug or feature