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?

Answer 1

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