java中的枚举类

1. 枚举类中枚举值序号（类似于数组下标）默认从0开始。要获取它的下标可以调用ordinal()方法实现。

    public enum Days{
        Monday,
        Tuesday,
        Wednesday,
        Thursday,
        Friday,
        Saturday,
        Sunday;
    }

    public static void main(String[] args) {
        System.out.println(Days.Sunday.ordinal());
    }

    2. 可以给枚举值添加各种属性，并且可以通过构造函数给枚举值赋予初始值，通过get,set方法更新枚举值的属性值。

public enum OrderStatusEnum {
        CANCELED(0, "已取消"),
        NO_PAY(10,"未支付"),
        PAID(20,"已付款"),
        SHIPPED(40,"已发货"),
        ORDER_SUCCESS(50,"订单完成"),
        ORDER_CLOSE(60,"订单关闭");

        private int code;
        private String value;

        OrderStatusEnum(int code, String value) {
            this.code = code;
            this.value = value;
        }

        public int getCode() {
            return code;
        }

        public void setCode(int code) {
            this.code = code;
        }

        public String getValue() {
            return value;
        }

        public void setValue(String value) {
            this.value = value;
        }
    }

    public static void main(String[] args) {
        OrderStatusEnum.CANCELED.setCode(1);
        System.out.println(OrderStatusEnum.CANCELED.getCode());
    }

    3. 枚举类一般可以定义在常量类中，如Const类当中。