5.6 枚举类

所有枚举类型都是Enum的子类

枚举类编写时就指明了它将有几个实例

    public enum Workday {

        Monday(1), Tuesday(2), Wednesday(3), Thursday(4), Friday(5);

        private int dayOfWeek;

        Workday(int dayOfWeek) {
            this.dayOfWeek = dayOfWeek;
        }
    }

每个枚举类型都有一个静态values方法，它将返回一个包含全部枚举值的数组

      Workday[] values = Workday.values();//[Monday, Tuesday, Wednesday, Thursday, Friday]