可以枚举枚举以添加新元素吗？ [英] Can enums be subclassed to add new elements?

问题描述

我想获取现有的枚举并添加更多元素，如下所示：

I want to take an existing enum and add more elements to it as follows:

enum A {a,b,c}

enum B extends A {d}

/*B is {a,b,c,d}*/

这在Java中是否可行？

Is this possible in Java?

推荐答案

不，你不能用Java做到这一点。除此之外， d 可能会是 A 的一个实例（假设扩展的正常概念） ，但只知道 A 的用户不会知道它 - 这会使枚举点成为一组众所周知的值。

No, you can't do this in Java. Aside from anything else, d would then presumably be an instance of A (given the normal idea of "extends"), but users who only knew about A wouldn't know about it - which defeats the point of an enum being a well-known set of values.

如果您可以告诉我们更多关于您如何使用的信息，我们可以建议其他解决方案。

If you could tell us more about how you want to use this, we could potentially suggest alternative solutions.

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