thenAcceptAsync

thenAcceptAsync is a method of Java's CompletableFuture used to perform a side-effect action after a stage completes, with the action executed asynchronously. The method consumes the result of the preceding stage but does not produce a new value, and it returns a new CompletableFuture<Void> that completes when the action itself finishes.

There are two overloads: thenAcceptAsync(Consumer<? super T> action) and thenAcceptAsync(Consumer<? super T> action, Executor executor). In both cases, when the previous stage completes normally, the provided Consumer is invoked with the stage’s result. If the preceding stage completes exceptionally, the returned CompletableFuture completes exceptionally and the action is not invoked.

If an Executor is supplied, the action runs using that executor. If no executor is provided, the action is scheduled to run asynchronously, typically in the common ForkJoinPool.

thenAcceptAsync contrasts with thenAccept, which may execute the action in the completion thread (potentially synchronously with the completing stage) rather than asynchronously. The Async variant ensures that the consumer runs asynchronously, enabling safer separation of concerns and avoiding blocking the completion thread.

Usage notes include that the action can perform side effects such as logging, I/O, or updating external state, without producing a value for downstream stages. Any exception thrown by the consumer causes the returned CompletableFuture to complete exceptionally, which can be handled via further composition methods such as exceptionally or handle.