Java 8 Stream 和对数组的操作 [英] Java 8 Stream and operation on arrays

问题描述

我刚刚发现了新的 Java 8 流功能.来自 Python，我想知道现在是否有一种巧妙的方法来对数组进行运算，例如求和，以一行 pythonic"方式将两个数组相乘?

I have just discovered the new Java 8 stream capabilities. Coming from Python, I was wondering if there was now a neat way to do operations on arrays like summing, multiplying two arrays in a "one line pythonic" way ?

谢谢

推荐答案

java.util.Arrays 中添加了一些新方法，可以将数组转换为 Java 8 流，然后可以将其用于求和等

There are new methods added to java.util.Arrays to convert an array into a Java 8 stream which can then be used for summing etc.

int sum =  Arrays.stream(myIntArray).sum();

将两个数组相乘有点困难，因为我想不出一种方法可以在 Stream 操作的同时获取值和索引.这意味着您可能必须对数组的索引进行流式处理.

Multiplying two arrays is a little more difficult because I can't think of a way to get the value AND the index at the same time as a Stream operation. This means you probably have to stream over the indexes of the array.

//in this example a[] and b[] are same length
int[] a = ...
int[] b = ...
 
int[] result = new int[a.length];

IntStream.range(0, a.length).forEach(i -> result[i] = a[i] * b[i]);

---

评论员 @Holger 指出您可以使用 map 方法代替 forEach 像这样:

---

Commenter @Holger points out you can use the map method instead of forEach like this:

int[] result = IntStream.range(0, a.length).map(i -> a[i] * b[i]).toArray();

这篇关于Java 8 Stream 和对数组的操作的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！