Dictionary Methods in Java

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.

Following are the methods defined by Dictionary are listed below −

Following is an example implementing put() and get() method of the Dictionary class −

Example

import java.util.*;
public class Demo {
   public static void main(String[] args) {
      Dictionary dictionary = new Hashtable();
      dictionary.put("20", "John");
      dictionary.put("40", "Tom");
      dictionary.put("60", "Steve");
      dictionary.put("80", "Kevin");
      dictionary.put("100", "Ryan");
      dictionary.put("120", "Tim");
      dictionary.put("140", "Jacob");
      dictionary.put("160", "David");
      System.out.println("Value at key 20 = " + dictionary.get("20"));
      System.out.println("Value at key 40 = " + dictionary.get("40"));
      System.out.println("Value at key 30 = " + dictionary.get("30"));
      System.out.println("Value at key 90 = " + dictionary.get("90"));
   }
}

Output

Value at key 20 = John
Value at key 40 = Tom
Value at key 30 = null
Value at key 90 = null

Let us see another example wherein we are displaying the Dictionary values as well using the elements () method −

Example

import java.util.*;
public class Demo {
   public static void main(String[] args) {
      Dictionary dictionary = new Hashtable();
      dictionary.put("20", "John");
      dictionary.put("40", "Tom");
      dictionary.put("60", "Steve");
      dictionary.put("80", "Kevin");
      dictionary.put("100", "Ryan");
      dictionary.put("120", "Tim");
      dictionary.put("140", "Jacob");
      dictionary.put("160", "David");
      System.out.println("Dictionary Values...");
      for (Enumeration i = dictionary.elements(); i.hasMoreElements();) {
         System.out.println(i.nextElement());
      }
      System.out.println("Value at key 20 = " + dictionary.get("20"));
      System.out.println("Value at key 40 = " + dictionary.get("40"));
      System.out.println("Value at key 30 = " + dictionary.get("30"));
      System.out.println("Value at key 90 = " + dictionary.get("90"));
   }
}

Output

Dictionary Values...
Tom
Jacob
Steve
Ryan
David
John
Kevin
Tim
Value at key 20 = John
Value at key 40 = Tom
Value at key 30 = null
Value at key 90 = null