带有Collection或List的Java 8 CompletableFuture.allOf（...） [英] Java 8 CompletableFuture.allOf(...) with Collection or List

问题描述

Java 8有一个函数 CompletableFuture.allOf（CompletableFuture<？> ... cfs） ，返回 CompletableFuture 在所有给定的期货完成时完成。

Java 8 has a function CompletableFuture.allOf(CompletableFuture<?>...cfs) that returns a CompletableFuture that is completed when all the given futures complete.

但是，我几乎总是没有处理<$ c $的数组c> CompletableFuture s，但是具有 List< CompletableFuture> 。当然，我可以使用 toArray（）方法，但是这必须经常在数组和列表之间来回转换，这有点痛苦。

However, I almost always am not dealing with an array of CompletableFutures, but instead have a List<CompletableFuture>. Of course, I can use the toArray() method, but this ends up being a bit of a pain to have to constantly convert back and forth between arrays and lists.

如果有一个光滑的方式获得 CompletableFuture< List< T>> ，那将是非常好的交换列表< CompletableFuture< T>> ，而不是经常投入中间数组创建。有没有人知道在Java 8中这样做的方法？

It would be really nice if there were a slick way get a CompletableFuture<List<T>> in exchange for a List<CompletableFuture<T>>, instead of constantly having to throw in an intermediary array creation. Does anyone know a way to do this in Java 8?

推荐答案

不幸的是，根据我的知识，可完成的期货不支持集合。

Unfortunately, to my knowledge completable futures does not support collections.

你可以做类似的事情来使代码更清洁，但它基本上做同样的事情：

You could do something like this to make the code a bit cleaner, but it essentially does the same thing :

public <T> CompletableFuture<List<T>> allOf(List<CompletableFuture<T>> futuresList) {
    CompletableFuture<Void> allFuturesResult =
    CompletableFuture.allOf(futuresList.toArray());
    return allFuturesResult.thenApply(v ->
            futuresList.stream().
                    map(future -> future.join()).
                    collect(Collectors.<T>toList())
    );
}

发现这个非常有用的信息： http://www.nurkiewicz.com/2013/05/java-8-completablefuture-in-action。 html

Found this very informative : http://www.nurkiewicz.com/2013/05/java-8-completablefuture-in-action.html

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