java.util
Class Hashtable<K,V>

java.lang.Object sample code for java.lang.Object definition code for java.lang.Object 
  extended by java.util.Dictionary sample code for java.util.Dictionary definition code for java.util.Dictionary <K,V>
      extended by java.util.Hashtable<K,V>
All Implemented Interfaces:
Serializable sample code for java.io.Serializable definition code for java.io.Serializable , Cloneable sample code for java.lang.Cloneable definition code for java.lang.Cloneable , Map sample code for java.util.Map definition code for java.util.Map <K,V>
Direct Known Subclasses:
Properties sample code for java.util.Properties definition code for java.util.Properties , UIDefaults sample code for javax.swing.UIDefaults definition code for javax.swing.UIDefaults

public class Hashtable<K,V>
extends Dictionary sample code for java.util.Dictionary definition code for java.util.Dictionary <K,V>
implements Map sample code for java.util.Map definition code for java.util.Map <K,V>, Cloneable sample code for java.lang.Cloneable definition code for java.lang.Cloneable , Serializable sample code for java.io.Serializable definition code for java.io.Serializable

This class implements a hashtable, which maps keys to values. Any non-null object can be used as a key or as a value.

To successfully store and retrieve objects from a hashtable, the objects used as keys must implement the hashCode method and the equals method.

An instance of Hashtable has two parameters that affect its performance: initial capacity and load factor. The capacity is the number of buckets in the hash table, and the initial capacity is simply the capacity at the time the hash table is created. Note that the hash table is open: in the case of a "hash collision", a single bucket stores multiple entries, which must be searched sequentially. The load factor is a measure of how full the hash table is allowed to get before its capacity is automatically increased. The initial capacity and load factor parameters are merely hints to the implementation. The exact details as to when and whether the rehash method is invoked are implementation-dependent.

Generally, the default load factor (.75) offers a good tradeoff between time and space costs. Higher values decrease the space overhead but increase the time cost to look up an entry (which is reflected in most Hashtable operations, including get and put).

The initial capacity controls a tradeoff between wasted space and the need for rehash operations, which are time-consuming. No rehash operations will ever occur if the initial capacity is greater than the maximum number of entries the Hashtable will contain divided by its load factor. However, setting the initial capacity too high can waste space.

If many entries are to be made into a Hashtable, creating it with a sufficiently large capacity may allow the entries to be inserted more efficiently than letting it perform automatic rehashing as needed to grow the table.

This example creates a hashtable of numbers. It uses the names of the numbers as keys:

     Hashtable numbers = new Hashtable();
     numbers.put("one", new Integer(1));
     numbers.put("two", new Integer(2));
     numbers.put("three", new Integer(3));
 

To retrieve a number, use the following code:

     Integer n = (Integer)numbers.get("two");
     if (n != null) {
         System.out.println("two = " + n);
     }
 

As of the Java 2 platform v1.2, this class has been retrofitted to implement Map, so that it becomes a part of Java's collection framework. Unlike the new collection implementations, Hashtable is synchronized.

The Iterators returned by the iterator and listIterator methods of the Collections returned by all of Hashtable's "collection view methods" are fail-fast: if the Hashtable is structurally modified at any time after the Iterator is created, in any way except through the Iterator's own remove or add methods, the Iterator will throw a ConcurrentModificationException. Thus, in the face of concurrent modification, the Iterator fails quickly and cleanly, rather than risking arbitrary, non-deterministic behavior at an undetermined time in the future. The Enumerations returned by Hashtable's keys and values methods are not fail-fast.

Note that the fail-fast behavior of an iterator cannot be guaranteed as it is, generally speaking, impossible to make any hard guarantees in the presence of unsynchronized concurrent modification. Fail-fast iterators throw ConcurrentModificationException on a best-effort basis. Therefore, it would be wrong to write a program that depended on this exception for its correctness: the fail-fast behavior of iterators should be used only to detect bugs.

This class is a member of the Java Collections Framework.

Since:
JDK1.0
See Also:
Object.equals(java.lang.Object) sample code for java.lang.Object.equals(java.lang.Object) definition code for java.lang.Object.equals(java.lang.Object) , Object.hashCode() sample code for java.lang.Object.hashCode() definition code for java.lang.Object.hashCode() , rehash() sample code for java.util.Hashtable.rehash() definition code for java.util.Hashtable.rehash() , Collection sample code for java.util.Collection definition code for java.util.Collection , Map sample code for java.util.Map definition code for java.util.Map , HashMap sample code for java.util.HashMap definition code for java.util.HashMap , TreeMap sample code for java.util.TreeMap definition code for java.util.TreeMap , Serialized Form

Constructor Summary
Hashtable sample code for java.util.Hashtable.Hashtable() definition code for java.util.Hashtable.Hashtable() ()
          Constructs a new, empty hashtable with a default initial capacity (11) and load factor, which is 0.75.
Hashtable sample code for java.util.Hashtable.Hashtable(int) definition code for java.util.Hashtable.Hashtable(int) (int initialCapacity)
          Constructs a new, empty hashtable with the specified initial capacity and default load factor, which is 0.75.
Hashtable sample code for java.util.Hashtable.Hashtable(int, float) definition code for java.util.Hashtable.Hashtable(int, float) (int initialCapacity, float loadFactor)
          Constructs a new, empty hashtable with the specified initial capacity and the specified load factor.
Hashtable sample code for java.util.Hashtable.Hashtable(java.util.Map) definition code for java.util.Hashtable.Hashtable(java.util.Map) (Map sample code for java.util.Map definition code for java.util.Map <? extends K,? extends V> t)
          Constructs a new hashtable with the same mappings as the given Map.
 
Method Summary
 void clear sample code for java.util.Hashtable.clear() definition code for java.util.Hashtable.clear() ()
          Clears this hashtable so that it contains no keys.
 Object sample code for java.lang.Object definition code for java.lang.Object clone sample code for java.util.Hashtable.clone() definition code for java.util.Hashtable.clone() ()
          Creates a shallow copy of this hashtable.
 boolean contains sample code for java.util.Hashtable.contains(java.lang.Object) definition code for java.util.Hashtable.contains(java.lang.Object) (Object sample code for java.lang.Object definition code for java.lang.Object  value)
          Tests if some key maps into the specified value in this hashtable.
 boolean containsKey sample code for java.util.Hashtable.containsKey(java.lang.Object) definition code for java.util.Hashtable.containsKey(java.lang.Object) (Object sample code for java.lang.Object definition code for java.lang.Object  key)
          Tests if the specified object is a key in this hashtable.
 boolean containsValue sample code for java.util.Hashtable.containsValue(java.lang.Object) definition code for java.util.Hashtable.containsValue(java.lang.Object) (Object sample code for java.lang.Object definition code for java.lang.Object  value)
          Returns true if this Hashtable maps one or more keys to this value.
 Enumeration sample code for java.util.Enumeration definition code for java.util.Enumeration <V> elements sample code for java.util.Hashtable.elements() definition code for java.util.Hashtable.elements() ()
          Returns an enumeration of the values in this hashtable.
 Set sample code for java.util.Set definition code for java.util.Set <Map.Entry sample code for java.util.Map.Entry definition code for java.util.Map.Entry <K,V>> entrySet sample code for java.util.Hashtable.entrySet() definition code for java.util.Hashtable.entrySet() ()
          Returns a Set view of the entries contained in this Hashtable.
 boolean equals sample code for java.util.Hashtable.equals(java.lang.Object) definition code for java.util.Hashtable.equals(java.lang.Object) (Object sample code for java.lang.Object definition code for java.lang.Object  o)
          Compares the specified Object with this Map for equality, as per the definition in the Map interface.
 V get sample code for java.util.Hashtable.get(java.lang.Object) definition code for java.util.Hashtable.get(java.lang.Object) (Object sample code for java.lang.Object definition code for java.lang.Object  key)
          Returns the value to which the specified key is mapped in this hashtable.
 int hashCode sample code for java.util.Hashtable.hashCode() definition code for java.util.Hashtable.hashCode() ()
          Returns the hash code value for this Map as per the definition in the Map interface.
 boolean isEmpty sample code for java.util.Hashtable.isEmpty() definition code for java.util.Hashtable.isEmpty() ()
          Tests if this hashtable maps no keys to values.
 Enumeration sample code for java.util.Enumeration definition code for java.util.Enumeration <K> keys sample code for java.util.Hashtable.keys() definition code for java.util.Hashtable.keys() ()
          Returns an enumeration of the keys in this hashtable.
 Set sample code for java.util.Set definition code for java.util.Set <K> keySet sample code for java.util.Hashtable.keySet() definition code for java.util.Hashtable.keySet() ()
          Returns a Set view of the keys contained in this Hashtable.
 V put sample code for java.util.Hashtable.put(K, V) definition code for java.util.Hashtable.put(K, V) (K key, V value)
          Maps the specified key to the specified value in this hashtable.
 void putAll sample code for java.util.Hashtable.putAll(java.util.Map) definition code for java.util.Hashtable.putAll(java.util.Map) (Map sample code for java.util.Map definition code for java.util.Map <? extends K,? extends V> t)
          Copies all of the mappings from the specified Map to this Hashtable These mappings will replace any mappings that this Hashtable had for any of the keys currently in the specified Map.
protected  void rehash sample code for java.util.Hashtable.rehash() definition code for java.util.Hashtable.rehash() ()
          Increases the capacity of and internally reorganizes this hashtable, in order to accommodate and access its entries more efficiently.
 V remove sample code for java.util.Hashtable.remove(java.lang.Object) definition code for java.util.Hashtable.remove(java.lang.Object) (Object sample code for java.lang.Object definition code for java.lang.Object  key)
          Removes the key (and its corresponding value) from this hashtable.
 int size sample code for java.util.Hashtable.size() definition code for java.util.Hashtable.size() ()
          Returns the number of keys in this hashtable.
 String sample code for java.lang.String definition code for java.lang.String toString sample code for java.util.Hashtable.toString() definition code for java.util.Hashtable.toString() ()
          Returns a string representation of this Hashtable object in the form of a set of entries, enclosed in braces and separated by the ASCII characters "" (comma and space).
 Collection sample code for java.util.Collection definition code for java.util.Collection <V> values sample code for java.util.Hashtable.values() definition code for java.util.Hashtable.values() ()
          Returns a Collection view of the values contained in this Hashtable.
 
Methods inherited from class java.lang.Object sample code for java.lang.Object definition code for java.lang.Object
finalize sample code for java.lang.Object.finalize() definition code for java.lang.Object.finalize() , getClass sample code for java.lang.Object.getClass() definition code for java.lang.Object.getClass() , notify sample code for java.lang.Object.notify() definition code for java.lang.Object.notify() , notifyAll sample code for java.lang.Object.notifyAll() definition code for java.lang.Object.notifyAll() , wait sample code for java.lang.Object.wait() definition code for java.lang.Object.wait() , wait sample code for java.lang.Object.wait(long) definition code for java.lang.Object.wait(long) , wait sample code for java.lang.Object.wait(long, int) definition code for java.lang.Object.wait(long, int)
 

Constructor Detail

Hashtable sample code for java.util.Hashtable(int, float) definition code for java.util.Hashtable(int, float)

public Hashtable(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 - the load factor of the hashtable.
Throws:
IllegalArgumentException sample code for java.lang.IllegalArgumentException definition code for java.lang.IllegalArgumentException - if the initial capacity is less than zero, or if the load factor is nonpositive.

Hashtable sample code for java.util.Hashtable(int) definition code for java.util.Hashtable(int)

public Hashtable(int initialCapacity)
Constructs a new, empty hashtable with the specified initial capacity and default load factor, which is 0.75.

Parameters:
initialCapacity - the initial capacity of the hashtable.
Throws:
IllegalArgumentException sample code for java.lang.IllegalArgumentException definition code for java.lang.IllegalArgumentException - if the initial capacity is less than zero.

Hashtable sample code for java.util.Hashtable() definition code for java.util.Hashtable()

public Hashtable()
Constructs a new, empty hashtable with a default initial capacity (11) and load factor, which is 0.75.


Hashtable sample code for java.util.Hashtable(java.util.Map<? extends K, ? extends V>) definition code for java.util.Hashtable(java.util.Map<? extends K, ? extends V>)

public Hashtable(Map sample code for java.util.Map definition code for java.util.Map <? extends K,? extends V> t)
Constructs a new hashtable with the same mappings as the given Map. The hashtable is created with an initial capacity sufficient to hold the mappings in the given Map and a default load factor, which is 0.75.

Parameters:
t - the map whose mappings are to be placed in this map.
Throws:
NullPointerException sample code for java.lang.NullPointerException definition code for java.lang.NullPointerException - if the specified map is null.
Since:
1.2
Method Detail

size sample code for java.util.Hashtable.size() definition code for java.util.Hashtable.size()

public int size()
Returns the number of keys in this hashtable.

Specified by:
size sample code for java.util.Map.size() definition code for java.util.Map.size() in interface Map sample code for java.util.Map definition code for java.util.Map <K,V>
Specified by:
size sample code for java.util.Dictionary.size() definition code for java.util.Dictionary.size() in class Dictionary sample code for java.util.Dictionary definition code for java.util.Dictionary <K,V>
Returns:
the number of keys in this hashtable.

isEmpty sample code for java.util.Hashtable.isEmpty() definition code for java.util.Hashtable.isEmpty()

public boolean isEmpty()
Tests if this hashtable maps no keys to values.

Specified by:
isEmpty sample code for java.util.Map.isEmpty() definition code for java.util.Map.isEmpty() in interface Map sample code for java.util.Map definition code for java.util.Map <K,V>
Specified by:
isEmpty sample code for java.util.Dictionary.isEmpty() definition code for java.util.Dictionary.isEmpty() in class Dictionary sample code for java.util.Dictionary definition code for java.util.Dictionary <K,V>
Returns:
true if this hashtable maps no keys to values; false otherwise.

keys sample code for java.util.Hashtable.keys() definition code for java.util.Hashtable.keys()

public Enumeration sample code for java.util.Enumeration definition code for java.util.Enumeration <K> keys()
Returns an enumeration of the keys in this hashtable.

Specified by:
keys sample code for java.util.Dictionary.keys() definition code for java.util.Dictionary.keys() in class Dictionary sample code for java.util.Dictionary definition code for java.util.Dictionary <K,V>
Returns:
an enumeration of the keys in this hashtable.
See Also:
Enumeration sample code for java.util.Enumeration definition code for java.util.Enumeration , elements() sample code for java.util.Hashtable.elements() definition code for java.util.Hashtable.elements() , keySet() sample code for java.util.Hashtable.keySet() definition code for java.util.Hashtable.keySet() , Map sample code for java.util.Map definition code for java.util.Map

elements sample code for java.util.Hashtable.elements() definition code for java.util.Hashtable.elements()

public Enumeration sample code for java.util.Enumeration definition code for java.util.Enumeration <V> 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 sample code for java.util.Dictionary.elements() definition code for java.util.Dictionary.elements() in class Dictionary sample code for java.util.Dictionary definition code for java.util.Dictionary <K,V>
Returns:
an enumeration of the values in this hashtable.
See Also:
Enumeration sample code for java.util.Enumeration definition code for java.util.Enumeration , keys() sample code for java.util.Hashtable.keys() definition code for java.util.Hashtable.keys() , values() sample code for java.util.Hashtable.values() definition code for java.util.Hashtable.values() , Map sample code for java.util.Map definition code for java.util.Map

contains sample code for java.util.Hashtable.contains(java.lang.Object) definition code for java.util.Hashtable.contains(java.lang.Object)

public boolean contains(Object sample code for java.lang.Object definition code for java.lang.Object  value)
Tests if some key maps into the specified value in this hashtable. This operation is more expensive than the containsKey method.

Note that this method is identical in functionality to containsValue, (which is part of the Map interface in the collections framework).

Parameters:
value - a value to search for.
Returns:
true if and only if some key maps to the value argument in this hashtable as determined by the equals method; false otherwise.
Throws:
NullPointerException sample code for java.lang.NullPointerException definition code for java.lang.NullPointerException - if the value is null.
See Also:
containsKey(Object) sample code for java.util.Hashtable.containsKey(java.lang.Object) definition code for java.util.Hashtable.containsKey(java.lang.Object) , containsValue(Object) sample code for java.util.Hashtable.containsValue(java.lang.Object) definition code for java.util.Hashtable.containsValue(java.lang.Object) , Map sample code for java.util.Map definition code for java.util.Map

containsValue sample code for java.util.Hashtable.containsValue(java.lang.Object) definition code for java.util.Hashtable.containsValue(java.lang.Object)

public boolean containsValue(Object sample code for java.lang.Object definition code for java.lang.Object  value)
Returns true if this Hashtable maps one or more keys to this value.

Note that this method is identical in functionality to contains (which predates the Map interface).

Specified by:
containsValue sample code for java.util.Map.containsValue(java.lang.Object) definition code for java.util.Map.containsValue(java.lang.Object) in interface Map sample code for java.util.Map definition code for java.util.Map <K,V>
Parameters:
value - value whose presence in this Hashtable is to be tested.
Returns:
true if this map maps one or more keys to the specified value.
Throws:
NullPointerException sample code for java.lang.NullPointerException definition code for java.lang.NullPointerException - if the value is null.
Since:
1.2
See Also:
Map sample code for java.util.Map definition code for java.util.Map

containsKey sample code for java.util.Hashtable.containsKey(java.lang.Object) definition code for java.util.Hashtable.containsKey(java.lang.Object)

public boolean containsKey(Object sample code for java.lang.Object definition code for java.lang.Object  key)
Tests if the specified object is a key in this hashtable.

Specified by:
containsKey sample code for java.util.Map.containsKey(java.lang.Object) definition code for java.util.Map.containsKey(java.lang.Object) in interface Map sample code for java.util.Map definition code for java.util.Map <K,V>
Parameters:
key - possible key.
Returns:
true if and only if the specified object is a key in this hashtable, as determined by the equals method; false otherwise.
Throws:
NullPointerException sample code for java.lang.NullPointerException definition code for java.lang.NullPointerException - if the key is null.
See Also:
contains(Object) sample code for java.util.Hashtable.contains(java.lang.Object) definition code for java.util.Hashtable.contains(java.lang.Object)

get sample code for java.util.Hashtable.get(java.lang.Object) definition code for java.util.Hashtable.get(java.lang.Object)

public V get(Object sample code for java.lang.Object definition code for java.lang.Object  key)
Returns the value to which the specified key is mapped in this hashtable.

Specified by:
get sample code for java.util.Map.get(java.lang.Object) definition code for java.util.Map.get(java.lang.Object) in interface Map sample code for java.util.Map definition code for java.util.Map <K,V>
Specified by:
get sample code for java.util.Dictionary.get(java.lang.Object) definition code for java.util.Dictionary.get(java.lang.Object) in class Dictionary sample code for java.util.Dictionary definition code for java.util.Dictionary <K,V>
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.
Throws:
NullPointerException sample code for java.lang.NullPointerException definition code for java.lang.NullPointerException - if the key is null.
See Also:
put(Object, Object) sample code for java.util.Hashtable.put(K, V) definition code for java.util.Hashtable.put(K, V)

rehash sample code for java.util.Hashtable.rehash() definition code for java.util.Hashtable.rehash()

protected void rehash()
Increases the capacity of and internally reorganizes this hashtable, in order to accommodate and access its entries more efficiently. This method is called automatically when the number of keys in the hashtable exceeds this hashtable's capacity and load factor.


put sample code for java.util.Hashtable.put(K, V) definition code for java.util.Hashtable.put(K, V)

public V put(K key,
             V 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 sample code for java.util.Map.put(K, V) definition code for java.util.Map.put(K, V) in interface Map sample code for java.util.Map definition code for java.util.Map <K,V>
Specified by:
put sample code for java.util.Dictionary.put(K, V) definition code for java.util.Dictionary.put(K, V) in class Dictionary sample code for java.util.Dictionary definition code for java.util.Dictionary <K,V>
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 sample code for java.lang.NullPointerException definition code for java.lang.NullPointerException - if the key or value is null.
See Also:
Object.equals(Object) sample code for java.lang.Object.equals(java.lang.Object) definition code for java.lang.Object.equals(java.lang.Object) , get(Object) sample code for java.util.Hashtable.get(java.lang.Object) definition code for java.util.Hashtable.get(java.lang.Object)

remove sample code for java.util.Hashtable.remove(java.lang.Object) definition code for java.util.Hashtable.remove(java.lang.Object)

public V remove(Object sample code for java.lang.Object definition code for java.lang.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 sample code for java.util.Map.remove(java.lang.Object) definition code for java.util.Map.remove(java.lang.Object) in interface Map sample code for java.util.Map definition code for java.util.Map <K,V>
Specified by:
remove sample code for java.util.Dictionary.remove(java.lang.Object) definition code for java.util.Dictionary.remove(java.lang.Object) in class Dictionary sample code for java.util.Dictionary definition code for java.util.Dictionary <K,V>
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.
Throws:
NullPointerException sample code for java.lang.NullPointerException definition code for java.lang.NullPointerException - if the key is null.

putAll sample code for java.util.Hashtable.putAll(java.util.Map<? extends K, ? extends V>) definition code for java.util.Hashtable.putAll(java.util.Map<? extends K, ? extends V>)

public void putAll(Map sample code for java.util.Map definition code for java.util.Map <? extends K,? extends V> t)
Copies all of the mappings from the specified Map to this Hashtable These mappings will replace any mappings that this Hashtable had for any of the keys currently in the specified Map.

Specified by:
putAll sample code for java.util.Map.putAll(java.util.Map) definition code for java.util.Map.putAll(java.util.Map) in interface Map sample code for java.util.Map definition code for java.util.Map <K,V>
Parameters:
t - Mappings to be stored in this map.
Throws:
NullPointerException sample code for java.lang.NullPointerException definition code for java.lang.NullPointerException - if the specified map is null.
Since:
1.2

clear sample code for java.util.Hashtable.clear() definition code for java.util.Hashtable.clear()

public void clear()
Clears this hashtable so that it contains no keys.

Specified by:
clear sample code for java.util.Map.clear() definition code for java.util.Map.clear() in interface Map sample code for java.util.Map definition code for java.util.Map <K,V>

clone sample code for java.util.Hashtable.clone() definition code for java.util.Hashtable.clone()

public Object sample code for java.lang.Object definition code for java.lang.Object  clone()
Creates a shallow copy of this hashtable. All the structure of the hashtable itself is copied, but the keys and values are not cloned. This is a relatively expensive operation.

Overrides:
clone sample code for java.lang.Object.clone() definition code for java.lang.Object.clone() in class Object sample code for java.lang.Object definition code for java.lang.Object
Returns:
a clone of the hashtable.
See Also:
Cloneable sample code for java.lang.Cloneable definition code for java.lang.Cloneable

toString sample code for java.util.Hashtable.toString() definition code for java.util.Hashtable.toString()

public String sample code for java.lang.String definition code for java.lang.String  toString()
Returns a string representation of this Hashtable object in the form of a set of entries, enclosed in braces and separated by the ASCII characters "" (comma and space). Each entry is rendered as the key, an equals sign =, and the associated element, where the toString method is used to convert the key and element to strings.

Overrides to toString method of Object.

Overrides:
toString sample code for java.lang.Object.toString() definition code for java.lang.Object.toString() in class Object sample code for java.lang.Object definition code for java.lang.Object
Returns:
a string representation of this hashtable.

keySet sample code for java.util.Hashtable.keySet() definition code for java.util.Hashtable.keySet()

public Set sample code for java.util.Set definition code for java.util.Set <K> keySet()
Returns a Set view of the keys contained in this Hashtable. The Set is backed by the Hashtable, so changes to the Hashtable are reflected in the Set, and vice-versa. The Set supports element removal (which removes the corresponding entry from the Hashtable), but not element addition.

Specified by:
keySet sample code for java.util.Map.keySet() definition code for java.util.Map.keySet() in interface Map sample code for java.util.Map definition code for java.util.Map <K,V>
Returns:
a set view of the keys contained in this map.
Since:
1.2

entrySet sample code for java.util.Hashtable.entrySet() definition code for java.util.Hashtable.entrySet()

public Set sample code for java.util.Set definition code for java.util.Set <Map.Entry sample code for java.util.Map.Entry definition code for java.util.Map.Entry <K,V>> entrySet()
Returns a Set view of the entries contained in this Hashtable. Each element in this collection is a Map.Entry. The Set is backed by the Hashtable, so changes to the Hashtable are reflected in the Set, and vice-versa. The Set supports element removal (which removes the corresponding entry from the Hashtable), but not element addition.

Specified by:
entrySet sample code for java.util.Map.entrySet() definition code for java.util.Map.entrySet() in interface Map sample code for java.util.Map definition code for java.util.Map <K,V>
Returns:
a set view of the mappings contained in this map.
Since:
1.2
See Also:
Map.Entry sample code for java.util.Map.Entry definition code for java.util.Map.Entry

values sample code for java.util.Hashtable.values() definition code for java.util.Hashtable.values()

public Collection sample code for java.util.Collection definition code for java.util.Collection <V> values()
Returns a Collection view of the values contained in this Hashtable. The Collection is backed by the Hashtable, so changes to the Hashtable are reflected in the Collection, and vice-versa. The Collection supports element removal (which removes the corresponding entry from the Hashtable), but not element addition.

Specified by:
values sample code for java.util.Map.values() definition code for java.util.Map.values() in interface Map sample code for java.util.Map definition code for java.util.Map <K,V>
Returns:
a collection view of the values contained in this map.
Since:
1.2

equals sample code for java.util.Hashtable.equals(java.lang.Object) definition code for java.util.Hashtable.equals(java.lang.Object)

public boolean equals(Object sample code for java.lang.Object definition code for java.lang.Object  o)
Compares the specified Object with this Map for equality, as per the definition in the Map interface.

Specified by:
equals sample code for java.util.Map.equals(java.lang.Object) definition code for java.util.Map.equals(java.lang.Object) in interface Map sample code for java.util.Map definition code for java.util.Map <K,V>
Overrides:
equals sample code for java.lang.Object.equals(java.lang.Object) definition code for java.lang.Object.equals(java.lang.Object) in class Object sample code for java.lang.Object definition code for java.lang.Object
Parameters:
o - object to be compared for equality with this Hashtable
Returns:
true if the specified Object is equal to this Map.
Since:
1.2
See Also:
Map.equals(Object) sample code for java.util.Map.equals(java.lang.Object) definition code for java.util.Map.equals(java.lang.Object)

hashCode sample code for java.util.Hashtable.hashCode() definition code for java.util.Hashtable.hashCode()

public int hashCode()
Returns the hash code value for this Map as per the definition in the Map interface.

Specified by:
hashCode sample code for java.util.Map.hashCode() definition code for java.util.Map.hashCode() in interface Map sample code for java.util.Map definition code for java.util.Map <K,V>
Overrides:
hashCode sample code for java.lang.Object.hashCode() definition code for java.lang.Object.hashCode() in class Object sample code for java.lang.Object definition code for java.lang.Object
Returns:
a hash code value for this object.
Since:
1.2
See Also:
Map.hashCode() sample code for java.util.Map.hashCode() definition code for java.util.Map.hashCode()