为什么 Java 的 Iterator 不是 Iterable? [英] Why is Java's Iterator not an Iterable?
问题描述
为什么Iterator
接口没有扩展Iterable
?
Why does the Iterator
interface not extend Iterable
?
iterator()
方法可以简单地返回 this
.
The iterator()
method could simply return this
.
这是故意的还是只是 Java 设计者的疏忽?
Is it on purpose or just an oversight of Java's designers?
能够使用带有迭代器的 for-each 循环会很方便:
It would be convenient to be able to use a for-each loop with iterators like this:
for(Object o : someContainer.listSomeObjects()) {
....
}
其中 listSomeObjects()
返回一个迭代器.
where listSomeObjects()
returns an iterator.
推荐答案
因为迭代器通常指向集合中的单个实例.Iterable 意味着可以从对象中获取一个迭代器来遍历它的元素——并且不需要迭代单个实例,这就是迭代器所代表的.
Because an iterator generally points to a single instance in a collection. Iterable implies that one may obtain an iterator from an object to traverse over its elements - and there's no need to iterate over a single instance, which is what an iterator represents.
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