获取forEach java 8的返回列表 [英] Getting return list from forEach java 8

问题描述

我正在尝试使用某个流，我认为我有一个概念性的误解。我试图采取一个数组，将其转换为一个流，然后.forEach项中的数组我想运行一个函数，并返回该函数的结果列表从foreach。

本质上是这样的：
$ b $ pre $ Thing [] functionedThings = Array.stream （东西）.forEach（东西 - > functionWithReturn（东西））


这可能吗？我使用错误的流功能？

解决方案

你在找什么叫做 map 操作：

pre $ Thing [] functionedThings = Arrays.stream（things）.map（thing - > functionWithReturn（thing））。toArray（Thing [] :: new）;


此方法用于将对象映射到另一个对象;引用Javadoc，它更好地说：



返回一个流，该流包含将给定函数应用到此流的元素的结果。

请注意，流将使用 toArray（generator）


I am trying to use a stream for something and I think I have a conceptual misunderstanding. I am trying to take an array, convert it to a stream, and .forEach item in the array I want to run a function and return a list of the results of that function from the foreach.

Essentially this:

Thing[] functionedThings = Array.stream(things).forEach(thing -> functionWithReturn(thing))

Is this possible? Am I using the wrong stream function?

解决方案

What you are looking for is called the map operation:

Thing[] functionedThings = Arrays.stream(things).map(thing -> functionWithReturn(thing)).toArray(Thing[]::new);

This method is used to map an object to another object; quoting the Javadoc, which says it better:

Returns a stream consisting of the results of applying the given function to the elements of this stream.

Note that the Stream is converted back to an array using the toArray(generator) method; the generator used is a function (it is actually a method reference here) returning a new Thing array.

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