java.util
Class Dictionary

java.lang.Object
  |
  +--java.util.Dictionary

Direct Known Subclasses:

Hashtable

public abstract class Dictionary

extends Object

The Dictionary class is the abstract parent of Hashtable, which maps keys to values. Any object can be used as a key and/or value.

See Also:

Hashtable, Object.hashCode(), Object.equals(java.lang.Object)

Constructor Summary

Dictionary()

Method Summary

abstract Enumeration	elements() Returns an enumeration of the elements.
abstract Object	get(Object key) Gets the object associated with the specified key in the Dictionary.
abstract boolean	isEmpty() Returns true if the Dictionary contains no elements.
abstract Enumeration	keys() Returns an enumeration of the Dictionary's keys.
abstract Object	put(Object key, Object value) Puts the specified element into the Dictionary, using the specified key.
abstract Object	remove(Object key) Removes the element corresponding to the key.
abstract int	size() Returns the number of elements contained within the Dictionary.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Dictionary

public Dictionary()

Method Detail

size

public abstract int size()

Returns the number of elements contained within the Dictionary.

isEmpty

public abstract boolean isEmpty()

Returns true if the Dictionary contains no elements.

keys

public abstract Enumeration keys()

Returns an enumeration of the Dictionary's keys.

See Also:

elements(), Enumeration

elements

public abstract Enumeration elements()

Returns an enumeration of the elements. Use the Enumeration methods on the returned object to fetch the elements sequentially.

See Also:

keys(), Enumeration

get

public abstract Object get(Object key)

Gets the object associated with the specified key in the Dictionary.

Parameters:

key - the key in the hash table

See Also:

put(java.lang.Object, java.lang.Object)

put

public abstract Object put(Object key,
                           Object value)

Puts the specified element into the Dictionary, using the specified key. The element may be retrieved by doing a get() with the same key. The key and the element cannot be null.

Parameters:

key - the specified hashtable key

value - the specified element

Returns:

the old value of the key, or null if it did not have one.

Throws:

NullPointerException - If the value of the specified element is null.

See Also:

get(java.lang.Object)

remove

public abstract Object remove(Object key)

Removes the element corresponding to the key. Does nothing if the key is not present.

Parameters:

key - the key that needs to be removed

Returns:

the value of key, or null if the key was not found.