Java - The Dictionary Class


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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The Dictionary class is obsolete.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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