java中的枚舉類

1. 枚舉類中枚舉值序號（類似於數組下標）默認從0開始。要獲取它的下標可以調用ordinal()方法實現。

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

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

    2. 可以給枚舉值添加各種屬性，並且可以通過構造函數給枚舉值賦予初始值，通過get,set方法更新枚舉值的屬性值。

public enum OrderStatusEnum {
        CANCELED(0, "已取消"),
        NO_PAY(10,"未支付"),
        PAID(20,"已付款"),
        SHIPPED(40,"已發貨"),
        ORDER_SUCCESS(50,"訂單完成"),
        ORDER_CLOSE(60,"訂單關閉");

        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. 枚舉類一般可以定義在常量類中，如Const類當中。