当第二阶段对第一阶段的结果值不感兴趣时​​，完成阶段链接 [英] CompletionStage chaining when 2nd stage is not interested in the 1st stage result value

问题描述

场景:

• 有两个阶段
• 第二阶段只有在第一阶段完成后才能执行
• 第二阶段对第一阶段的结果不感兴趣，而只是对第一阶段的完成感兴趣

考虑现有方法:

public <U> CompletionStage<U> thenApply(Function<? super T,? extends U> fn);

它不能完全满足我的需要，因为该函数知道第一阶段结果值? super T

It doesn't quite satisfy my needs cause the function is aware of the 1st stage result value ? super T

我想拥有的东西是这样的:

What I would rather like to have is something like:

public <U> CompletionStage<U> thenApply(Supplier<? extends U> fn);

问题:我是否正确理解没有针对此问题的即用型解决方案，所以我必须编写自己的包装函数才能实现所需的行为?

Question: do I understand correctly that there's no out-of-the-box solution for that so I will have to write my own wrapper function in order to achieve the desired behavior?

推荐答案

没有这样的内置解决方案.但是您可以滥用" CompletableFuture.supplyAsync 和

There is no such built-in solution. But you could "abuse" CompletableFuture.supplyAsync and thenCompose:

Supplier<String> sup = ()->"s";
CompletableFuture.supplyAsync(()->4)
        .thenCompose(x->CompletableFuture.supplyAsync(sup))
        .thenAccept(System.out::println);

顺便说一句，我想可能没有这样的便捷方法，因为CompletionStage/CompletableFuture已经有很多方法了.

BTW, I guess probably there are no such convenience methods because CompletionStage/CompletableFuture already have quite many methods.

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