如何使用Streams api peek（）函数并使其工作？ [英] How to use Streams api peek() function and make it work?

问题描述

根据这个问题， peek（）很懒，这意味着我们应该以某种方式激活它。事实上，要激活它以向控制台输出内容我尝试了这个：

According to this question, peek() is lazy it means we should somehow activate it. In fact, to activate it to print something out to the console I tried this :

Stream<String> ss = Stream.of("Hi","Hello","Halo","Hacker News");
ss.parallel().peek(System.out::println);
System.out.println("lol"); // I wrote this line to print sth out to terminal to wake peek method up

但是没有工作和输出是：

But that doesn't work and the output is :

lol

因此，如何让 peek 函数真正起作用？

Thus, how can I make the peek function actually work?

如果没有办法，那么使用 peek 是什么意思？

If there is no way to that so whats the point of using peek?

推荐答案

你必须使用终端操作在流上执行（peek不是终端，它是一个中间操作，返回一个新流），例如count（）：

You have to use terminal operation on a stream for it to execute (peek is not terminal, it is an intermediate operation, that returns a new Stream), e.g. count():

Stream<String> ss = Stream.of("Hi","Hello","Halo","Hacker News");
ss.parallel().peek(System.out::println).count();

或用<$ c $替换 peek c> forEach （这是终端）：

Or replace peek with forEach (which is terminal):

    ss.parallel().forEach(System.out::println);

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