Tuesday, March 19, 2013

The Dictionary Class


Dictionary is an abstract class that represents a key/value storage repository and operates much like Map.
Given a key and value, you can store the value in a Dictionary object. Once the value is stored, you can retrieve it by using its key. Thus, like a map, a dictionary can be thought of as a list of key/value pairs.
The abstract methods defined by Dictionary are listed below:
SN
Methods with Description
1
Enumeration elements( )
Returns an enumeration of the values contained in the dictionary.
2
Object get(Object key)
Returns the object that contains the value associated with key. If key is not in the dictionary, a null object is returned.
3
boolean isEmpty( )
Returns true if the dictionary is empty, and returns false if it contains at least one key.
4
Enumeration keys( )
Returns an enumeration of the keys contained in the dictionary.
5
Object put(Object key, Object value)
Inserts a key and its value into the dictionary. Returns null if key is not already in the dictionary; returns the previous value associated with key if key is already in the dictionary.
6
Object remove(Object key)
Removes key and its value. Returns the value associated with key. If key is not in the dictionary, a null is returned.
7
int size( )
Returns the number of entries in the dictionary.
The Dictionary class is obsolete. You should implement the Map interface to obtain key/value storage functionality.

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