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. Although not currently deprecated, Dictionary is classified as obsolete, because it is fully superseded by Map
class Dictionary<K, V>
Here, K specifies the type of keys, and V specifies the type of values
The Abstract Methods Defined by Dictionary
| Method | Purpose |
| Enumeration<V> elements( ) | Returns an enumeration of the values contained in the dictionary. |
| V 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. | |
| boolean isEmpty( ) | Returns true if the dictionary is empty, and returns false if it |
| contains at least one key. | |
| Enumeration<K> keys( ) | Returns an enumeration of the keys contained in the dictionary. |
| V put(K key, V 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. | |
| V 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. | |
| int size( ) | Returns the number of entries in the dictionary. |
To add a key and a value, use the put( ) method. Use get( ) to retrieve the value of a given key. The keys and values can each be returned as an Enumeration by the keys( ) and elements( ) methods, respectively. The size( ) method returns the number of key/value pairs stored in a dictionary, and isEmpty( ) returns true when the dictionary is empty. You can use the remove( ) method to delete a key/value pair.