如何在Java 8中从有限流构建无限重复流？ [英] How do you build an infinite repeating stream from a finite stream in Java 8?

问题描述

如何将有限的事物流 Stream< Thing> 变成无限重复的事物流？

How can I turn a finite Stream of things Stream<Thing> into an infinite repeating stream of things?

推荐答案

Boris the Spider是对的：Stream只能遍历一次，所以你需要供应商< Stream< Thing>> 或者你需要一个收藏。

Boris the Spider is right: a Stream can only be traversed once, so you need a Supplier<Stream<Thing>> or you need a Collection.

<T> Stream<T> repeat(Supplier<Stream<T>> stream) {
    return Stream.generate(stream).flatMap(s -> s);
}

<T> Stream<T> repeat(Collection<T> collection) {
    return Stream.generate(() -> collection.stream()).flatMap(s -> s);
}

示例调用：

Supplier<Stream<Thing>> stream = () ->
    Stream.of(new Thing(1), new Thing(2), new Thing(3));

Stream<Thing> infinite = repeat(stream);
infinite.limit(50).forEachOrdered(System.out::println);

System.out.println();

Collection<Thing> things =
    Arrays.asList(new Thing(1), new Thing(2), new Thing(3));

Stream<Thing> infinite2 = repeat(things);
infinite2.limit(50).forEachOrdered(System.out::println);

这篇关于如何在Java 8中从有限流构建无限重复流？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！