/* --------------------------------------
   Iterate over the keys in a Map
   -------------------------------------- */


import java.util.*;


public class Map3
{
   public static void main(String[] args)
   {

      Map<String, String> M = new HashMap<String, String>();


      M.put("John Doe", "Brother");
      System.out.println(M);

      M.put("Tom Doe", "Cousin");
      System.out.println(M);

      M.put("Jane Doe", "Sister");
      System.out.println(M);

      M.put("Todd Hall", "Neighbor");
      System.out.println(M);

      M.put("Ralph Smith", "Teacher");
      System.out.println(M);

      System.out.println();

      /* ------------------------------------------------
	 entrySet() returns a  "Set<Map.Entry<K,V>>"
	 or: a "Set" of <Map.Entry> items
         ----------------------------------------------- */
      Collection<String> s = M.keySet();

      /* ------------------------------------------------
         Get an iterator over a Set
         ----------------------------------------------- */
      Iterator iter = s.iterator();


      /* -------------------------
	 Iterate over "iter"
         ------------------------- */
      while(iter.hasNext()) 
      {
         String x;    // Help variable

         x = (String) iter.next();		// Get next entry

         System.out.println(x);
      }
      System.out.println(); 

   }

}