CompletableFuture VS @Async

Question

I am not good at English.

I use asynchronous methods.

Option 1

public CompletableFuture<Integer> getDiscountPriceAsync(Integer price) {
        return CompletableFuture.supplyAsync(() -> {
            log.info("supplyAsync");
            return (int)(price * 0.9);
        }, threadPoolTaskExecutor);
    }

Option 2

@Async
public CompletableFuture<Integer> getDiscountPriceAsync(Integer price) {
        return CompletableFuture.supplyAsync(() -> {
            log.info("supplyAsync");
            return (int)(price * 0.9);
        }, threadPoolTaskExecutor);
    }

I wonder what the difference is between using @Async and not using it.

I think the first Option1 provides enough asynchronous methods.
However, is it correct to use it like Option2?

Related: [What advantage is there to using Spring @Async vs. CompleteableFuture directly?](https://stackoverflow.com/q/44685187/525036) — Didier L, May 04 '20 at 09:57

score 10 · Accepted Answer · answered Apr 24 '20 at 09:58

10

Option 2 is asynchronous done twice.

If you annotated a method withe @Async it will be executed by Spring asynchronously. So you don't need to use the ThreadPoolExecutor by yourself.

Instead you could write:

@Async
public CompletableFuture<Integer> getDiscountPriceAsync(Integer price) {
    log.info("supplyAsync");

    return new AsyncResult<Integer>((int)(price * 0.9)); 
}

Read more about Async with Spring here: https://www.baeldung.com/spring-async

answered Apr 24 '20 at 09:58

Simon Martinelli

34,053
5
48
82

If my answer was helpful, please accept it. Thank you – Simon Martinelli Apr 25 '20 at 08:58
To return CompleteFuture, I have to use the complete() method of AsyncResult. --> return new AsyncResult<>((int) (price * 0.9)).completable(); – Eddy Kim Apr 25 '20 at 10:58
1

@EddyKim, you can also use `return CompletableFuture.completedFuture((int)(price * 0.9));` – Didier L May 04 '20 at 09:55
1

I can update my answer but before: Do you really need a CompletableFuture? Wouldn't Future be good enough? – Simon Martinelli May 04 '20 at 11:15
@DidierL I like your comment! – yuen26 Jul 14 '21 at 07:10

CompletableFuture VS @Async

1 Answers1