Java.util.EnumMap.keySet() 方法

package com.codingdict;

import java.util.*;

public class EnumMapDemo {

   // create an enum
   public enum Numbers {
      ONE, TWO, THREE, FOUR, FIVE
   };

   public static void main(String[] args) {

      EnumMap<Numbers, String> map =
         new EnumMap<Numbers, String>(Numbers.class);

      // associate values in map
      map.put(Numbers.ONE, "1");
      map.put(Numbers.TWO, "2");
      map.put(Numbers.THREE, "3");
      map.put(Numbers.FOUR, "4");

      // print the map
      System.out.println("Map: " + map);

      // create a new set and return the set view of the keys contained
      Set<Numbers> set = map.keySet();

      // print the set
      System.out.println("Set: " + set);
   }
}