Java.util.Dictionary Class in Java

07 Dec, 2021
util.Dictionary is an abstract class, representing a key-value relation and works similar to a map. Given a key you can store values and when needed can retrieve the value back using its key. Thus, it is a list of key-value pair. 
Declaration 
public abstract class Dictionary extends Object
Constructors: Dictionary() Sole constructor. 
Methods of util.Dictionary Class : 
1. put(K key, V value) : java.util.Dictionary.put(K key, V value) adds key-value pair to the dictionary.
Syntax :
public abstract V put(K key, V value)
Parameters : 
-> key
-> value
Return : 
key-value pair mapped in the dictionary
2. elements() : java.util.Dictionary.elements() returns value representation in dictionary.
Syntax :
public abstract Enumeration elements()
Parameters : 
--------
Return : 
value enumeration in dictionary
3. get(Object key) : java.util.Dictionary.get(Object key) returns the value that is mapped with the argumented key in the dictionary.
Syntax :
public abstract V get(Object key)
Parameters : 
key - key whose mapped value we want
Return : 
value mapped with the argumented key
4. isEmpty() : java.util.Dictionary.isEmpty() checks whether the dictionary is empty or not. 
Syntax :
public abstract boolean isEmpty()
Parameters : 
------
Return : 
true, if there is no key-value relation in the dictionary; else false
5. keys() : java.util.Dictionary.keys() returns key representation in dictionary.
Syntax :
public abstract Enumeration keys()
Parameters : 
--------
Return : 
key enumeration in dictionary
6. remove(Object key) : java.util.Dictionary.remove(Object key) removes the key-value pair mapped with the argumented key. 
Syntax :
public abstract V remove(Object key)
Parameters : 
key : key to be removed
Return : 
value mapped with the key
7. size() : java.util.Dictionary.size() returns the no. of key-value pairs in the Dictionary.
Syntax :
public abstract int size()
Parameters : 
-------
Return : 
returns the no. of key-value pairs in the Dictionary
Java
// Java Program explaining util.Dictionary class Methods// put(), elements(), get(), isEmpty(), keys()// remove(), size() import java.util.*;public class New_Class{    public static void main(String[] args)    {         // Initializing a Dictionary        Dictionary geek = new Hashtable();         // put() method        geek.put("123", "Code");        geek.put("456", "Program");         // elements() method :        for (Enumeration i = geek.elements(); i.hasMoreElements();)        {            System.out.println("Value in Dictionary : " + i.nextElement());        }         // get() method :        System.out.println("\nValue at key = 6 : " + geek.get("6"));        System.out.println("Value at key = 456 : " + geek.get("123"));         // isEmpty() method :        System.out.println("\nThere is no key-value pair : " + geek.isEmpty() + "\n");         // keys() method :        for (Enumeration k = geek.keys(); k.hasMoreElements();)        {            System.out.println("Keys in Dictionary : " + k.nextElement());        }         // remove() method :        System.out.println("\nRemove : " + geek.remove("123"));        System.out.println("Check the value of removed key : " + geek.get("123"));         System.out.println("\nSize of Dictionary : " + geek.size());     }}
Output: 
Value in Dictionary : Code
Value in Dictionary : Program

Value at key = 6 : null
Value at key = 456 : Code

There is no key-value pair : false

Keys in Dictionary : 123
Keys in Dictionary : 456

Remove : Code
Check the value of removed key : null

Size of Dictionary : 1
This article is contributed by Mohit Gupta_OMG . If you like GeeksforGeeks and would like to contribute, you can also write an article using write.geeksforgeeks.org or mail your article to review-team@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above. 
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