一次从流中选择2个元素 [英] pick 2 elements from stream at a time

问题描述

假设我们有一个集合（或流？）

Suppose we have a collection (or stream?)

{"1","2","3","4"...}

现在我们想要两个元素并组成一对像这样

now we want to take two elements and compose a pair like this

{{"1","2"}, {"2","3"},{"3","4"}..}

我们知道如何以丑陋的方式（for loop）。

We know how to do that the ugly way (for loop).

我想知道我们如何用java 8流做这个？

I wonder how do we do this with java 8 streams?

因为java流和被动扩展中的方法是几乎相同（都是monad）我认为可能有类似的东西RX .pick（2）这会在2个元素到达时触发事件......

Because approaches in java streams and reactive extensions are pretty much same (both are monads) I thought there might be something alike RX .pick(2) which would trigger event when 2 elements arrive...

推荐答案

可以使用 IntStream.range 循环流 - 类 - 的方式。

It is possible to use the IntStream.range to loop in a stream-kind-of-way.

String[] str = {"1", "2", "3", "4"};
final String[][] result = IntStream.range(0, str.length - 1)
        .mapToObj(i -> new String[]{str[i], str[i + 1]})
        .toArray(String[][]::new);

结果包含 {{1，2}，{ 2，3}，{3，4}} 。

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