Java Dictionary Class with Example

Dictionary in Java is an abstract class that represents a key/value storage repository and operates as a map. If we have a key-value pair then we can store the value in the Dictionary object. Once the value is stored in a dictionary object, we can retrieve it by using its key. In Dictionary, any non-null object can be used as a key and as a value. 

Methods of Java Dictionary

The abstract methods defined by Java Dictionary are listed below:

1. Object put(Object key, Object value): This method is used to insert a key/value pair into a Dictionary.

2. Object get(Object key): It returns the object that contains the value associated with the key.

3. boolean isEmpty(): It checks whether the Dictionary is empty or not. If the Dictionary is empty it will return true else return false.

4. int size(): Returns the number of key/value pair in the dictionary.

5. Enumeration elements(): This method returns an enumeration of the values contained in the dictionary.

6. Enumeration keys(): This method returns an enumeration of the keys contained in the dictionary.

Java Dictionary Example:

import java.util.*;
class DictionaryExample{
 public static void main(String args[]){
  
  //creating a dictionary
  Dictionary dict = new Hashtable();
  
  //adding values in this dictionary
  dict.put(101, "Rahul");
  dict.put(109, "Amit");
  dict.put(103, "Vijay");
  dict.put(102, "Suresh");
  dict.put(108, "Prashant");
  
  //returns size of the dictionary
  System.out.println("Dictionary size is: "+dict.size());
  
  //enumeration of the values contained in the dictionary.
  for(Enumeration enm = dict.elements(); enm.hasMoreElements();){
   System.out.println("Dictionary values are: "+enm.nextElement());
  }
  
  //returns the value at key 108.
  System.out.println("Retrieve value at key 108: " +dict.get(108));
  
  //returns a boolean value
  System.out.println("Check dictionary is empty or not: " +dict.isEmpty());
  
  //enumeration of the keys contained in the dictionary.
  for(Enumeration enm = dict.keys(); enm.hasMoreElements();){
   System.out.println("Dictionary keys are: "+enm.nextElement());
  }
 }
}

Output:

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