为什么枚举不可以进行？ [英] Why aren't Enumerations Iterable?

问题描述

在Java 5及以上版本中，你有foreach循环，它可以实现任何实现 Iterable ：

In Java 5 and above you have the foreach loop, which works magically on anything that implements Iterable:

for (Object o : list) {
  doStuff(o);
}

然而，可枚举仍然没有实现 Iterable ，这意味着迭代 Enumeration 你必须执行以下操作：

However, Enumerable still does not implement Iterable, meaning that to iterate over an Enumeration you must do the following:

for(; e.hasMoreElements() ;) {
  doStuff(e.nextElement());
}

有没有人知道是否有枚举的原因仍然没有实现 Iterable ？

Does anyone know if there is a reason why Enumeration still does not implement Iterable?

编辑作为澄清，我不是在谈论枚举的语言概念，我正在谈论Java API中特定于Java的类，名为枚举。

As a clarification, I'm not talking about the language concept of an enum, I'm talking a Java-specific class in the Java API called 'Enumeration'.

推荐答案

枚举尚未修改为支持Iterable，因为它是一个不是具体类的接口（如Vector，它被修改为支持Collections接口）。

Enumeration hasn't been modified to support Iterable because it's an interface not a concrete class (like Vector, which was modifed to support the Collections interface).

如果Enumeration被更改为支持Iterable，它会破坏一堆人的代码。

If Enumeration was changed to support Iterable it would break a bunch of people's code.

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