Hashtable (Codename One API)

java.lang.Object
- java.util.Dictionary<K,V>
- - java.util.Hashtable<K,V>

All Implemented Interfaces:

Map<K,V>
```
public class Hashtable<K,V>
extends Dictionary<K,V>
implements Map<K,V>
```
Hashtable associates keys with values. Both 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()

Constructor Summary

Constructors
Constructor and Description
`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

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`void`	`clear()` Removes all key/value pairs from this `Hashtable`, leaving the size zero and the capacity unchanged.
`boolean`	`contains(Object value)` Returns true if this `Hashtable` contains the specified object as the value of at least one of the key/value pairs.
`boolean`	`containsKey(Object key)` Returns true 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 this `Hashtable` with the specified object and indicates if they are equal.
`V`	`get(Object key)` Returns the value associated with the specified key in this `Hashtable`.
`int`	`hashCode()` Returns a hash code value for the object.
`boolean`	`isEmpty()` Returns true if this `Hashtable` has no key/value pairs.
`Enumeration<K>`	`keys()` Returns an enumeration on the keys of this `Hashtable` instance.
`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 to this `Hashtable` from the specified map.
`protected void`	`rehash()` Increases the capacity of this `Hashtable`.
`V`	`remove(Object key)` Removes 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
clone, getClass, notify, notifyAll, wait, wait, wait

- 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()
  - contains
```
public boolean contains(Object value)
```
    Returns true 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 true 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 this Hashtable with the specified object and indicates if they are equal. In order to be equal, 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, or null if the specified key does not exist.
    
    See Also:
    
    put(K, V)
  - hashCode
```
public int hashCode()
```
    Description copied from class: Object
    
    Returns a hash code value for the object. This method is supported for the benefit of hashtables such as those provided by java.util.Hashtable. The general contract of hashCode is: Whenever it is invoked on the same object more than once during an execution of a Java application, the hashCode method must consistently return the same integer, provided no information used in equals comparisons on the object is modified. This integer need not remain consistent from one execution of an application to another execution of the same application. If two objects are equal according to the equals(Object) method, then calling the hashCode method on each of the two objects must produce the same integer result. It is not required that if two objects are unequal according to the equals(java.lang.Object) method, then calling the hashCode method on each of the two objects must produce distinct integer results. However, the programmer should be aware that producing distinct integer results for unequal objects may improve the performance of hashtables. As much as is reasonably practical, the hashCode method defined by class Object does return distinct integers for distinct objects. (This is typically implemented by converting the internal address of the object into an integer, but this implementation technique is not required by the JavaTM programming language.)
    
    Specified by:
    
    hashCode in interface Map<K,V>
    
    Overrides:
    
    hashCode in class Object
    
    Returns:
    
    the receiver's hash.
    
    See Also:
    
    Map.equals(Object)
  - isEmpty
```
public boolean isEmpty()
```
    Returns true if this Hashtable has no key/value pairs.
    
    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 instance. 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, or 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 to this Hashtable from the specified map.
    
    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 called when the size of this Hashtable exceeds the load factor.
  - remove
```
public V remove(Object key)
```
    Removes 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, or 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.

Class Hashtable<K,V>

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

Hashtable

Hashtable

Hashtable

Hashtable

Method Detail

clear

contains

containsKey

containsValue

elements

entrySet

equals

get

hashCode

isEmpty

keys

keySet

put

putAll

rehash

remove

size

toString

values