优点：常量做为Key，在编译期就确定了。Enum做为key，在运行时也可以改变

package enumdemo;import java.util.EnumMap;import java.util.Map;import java.util.Set;public class EnumMaps {    public static void main(String[] args) {        EnumMap
     
       em = new EnumMap
      
       (AlarmPoints.class);        em.put(AlarmPoints.KITCHEN, new Command() {            @Override            public void action() {                System.out.println("action:kitchen...");            }        });        em.put(AlarmPoints.BATHROOM, new Command() {            @Override            public void action() {                System.out.println("action:bathroom");            }        });        Set
       
        
         > set = em.entrySet();        for (Map.Entry
         
           entry : set) {            System.out.println(entry.getKey() + "");            entry.getValue().action();        }        System.out.println(em.get(AlarmPoints.UTILITY) + "");    }}enum AlarmPoints {    KITCHEN,    BATHROOM,    UTILITY}interface Command {    void action();}