java.lang.Enum

 Day day = Day.MONDAY;
        //获取对象所代表的那个枚举类型的值
        System.out.println(day.name());  //MONDAY
        
        //当前枚举常量在所定义的枚举类型中所在的位置
        System.out.println("ordinal: "+ day.ordinal()); //1
        //比较是否类型与值都相同
        System.out.println(day.equals("MONDAY")); //false
        
        System.out.println("hashcode:"+ day.hashCode());
        
        //比较同一个Enum中的数据的顺序。顺序比参数大则为正数，小为负数，相同为0.返回值就是位置相差的的个数
        System.out.println("compareTo: "+ day.compareTo(Day.SATURDAY));//-5
        
        //获得枚举对象的类
        System.out.println(day.getDeclaringClass());