如何将 Java 8 Stream 转换为数组? [英] How to convert a Java 8 Stream to an Array?

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问题描述

将 Java 8 Stream 转换为数组的最简单/最短的方法是什么?

What is the easiest/shortest way to convert a Java 8 Stream into an array?

推荐答案

最简单的方法是使用带有数组构造函数引用的 toArray(IntFunction generator) 方法.这在 该方法的 API 文档.

The easiest method is to use the toArray(IntFunction<A[]> generator) method with an array constructor reference. This is suggested in the API documentation for the method.

String[] stringArray = stringStream.toArray(String[]::new);

它所做的是找到一个以整数(大小)作为参数的方法,并返回一个String[],这正是的(重载之一)new String[] 确实如此.

What it does is find a method that takes in an integer (the size) as argument, and returns a String[], which is exactly what (one of the overloads of) new String[] does.

您也可以编写自己的IntFunction:

Stream<String> stringStream = ...;
String[] stringArray = stringStream.toArray(size -> new String[size]);

IntFunction的目的generator 是将一个整数,即数组的大小,转换为一个新的数组.

The purpose of the IntFunction<A[]> generator is to convert an integer, the size of the array, to a new array.

示例代码:

Stream<String> stringStream = Stream.of("a", "b", "c");
String[] stringArray = stringStream.toArray(size -> new String[size]);
Arrays.stream(stringArray).forEach(System.out::println);

打印:

a
b
c

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