java 同时拥有 Iterator.forEachRemaining() 和 Iterable.forEach() 有什么意义？
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what's the point of having both Iterator.forEachRemaining() and Iterable.forEach()?
提问by mostafa.S
and both of them get a Consumer as parameter. so if Java 8, is meant to avoid confusions, like it has done in Time API, why has it added a new confusion? or am I missing some point?
并且他们都得到一个 Consumer 作为参数。所以如果 Java 8 是为了避免混淆，就像它在 Time API 中所做的那样，为什么它增加了一个新的混淆？或者我错过了什么？
回答by Sweeper
To understand why the two methods both exist, you need to first understand what are Iteratorand Iterable.
要了解为什么这两种方法都存在，您首先需要了解什么是Iterator和Iterable。
An Iteratorbasically is something that has a "next element" and usually, an end.
一个Iterator基本的东西，有一个“未来元素”，通常，一个结束。
An Iterableis something that contains elements in a finite or infinite sequence and hence, can be iteratedover by keep getting the next element. In other words, Iterables can be iterated over by Iterators.
AnIterable是包含有限或无限序列中的元素的东西，因此可以通过不断获取下一个元素来迭代。换句话说，Iterables 可以被 s 迭代Iterator。
Now that you understand this, I can talk about what's the difference between the two methods in question.
既然明白了这一点，我就可以谈谈所讨论的两种方法之间的区别。
Let's use an array list as an example. This is what is inside the array list:
我们以数组列表为例。这是数组列表中的内容：
[1, 3, 6, 8, 0]
Now if I call Iterable.forEach()and pass in System.out::print(), 13680will be printed. This is because Iterable.forEachiterates through the whole sequence of elements.
现在，如果我调用Iterable.forEach()并传入System.out::print()，13680将被打印。这是因为Iterable.forEach遍历整个元素序列。
On the other hand, if I get the Iteratorof the array list and called nexttwice, before calling forEachRemainingwith System.out::print(), 680will be printed. The Iteratorhas already iterated through the first two elements, so the "remaining" ones are 6, 8 and 0.
另一方面，如果我获得Iterator数组列表的 并调用next两次，则在调用forEachRemainingwith之前System.out::print()，680将打印。在Iterator已经通过前两个元素迭代，因此，“剩余”的有6,8和0。
