Keys from HashtTable in java pgm

Set View of Keys from HashtTable

import java.util.Enumeration;

import java.util.Hashtable;

public class Main

{

   public static void main(String[] args)

   {

      Hashtable ht = new Hashtable();

      ht.put("1", "One");

      ht.put("2", "Two");

      ht.put("3", "Three");

      Enumeration e = ht.keys();

      while (e.hasMoreElements())

     {

         System.out.println(e.nextElement());

      }

   }

}