Is it possible to schedule a CompletableFuture?

As said, there is support in Java 9.

But it’s not hard to create a similar feature under Java 8; you already named the necessary elements:

// prefer this constructor with zero core threads for a shared pool,
// to avoid blocking JVM exit
static final ScheduledExecutorService SCHEDULER = new ScheduledThreadPoolExecutor(0);
static Executor delayedExecutor(long delay, TimeUnit unit)
  return delayedExecutor(delay, unit, ForkJoinPool.commonPool());
static Executor delayedExecutor(long delay, TimeUnit unit, Executor executor)
  return r -> SCHEDULER.schedule(() -> executor.execute(r), delay, unit);

which can be used similarly to the Java 9 feature:

Executor afterTenSecs = delayedExecutor(10L, TimeUnit.SECONDS);
CompletableFuture<String> future 
  = CompletableFuture.supplyAsync(() -> "someValue", afterTenSecs);


Care must be taken to avoid that the shared scheduled executor’s threads prevent the JVM from terminating. The alternative to a zero core pool size is to use daemon threads:

static final ScheduledExecutorService SCHEDULER
  = Executors.newSingleThreadScheduledExecutor(r -> {
    Thread t = new Thread(r);
    return t;

If you're using Java 9+ then CompletableFuture#delayedExecutor(long,TimeUnit) may fit your needs:

Returns a new Executor that submits a task to the default executor after the given delay (or no delay if non-positive). Each delay commences upon invocation of the returned executor's execute method.

Executor delayed = CompletableFuture.delayedExecutor(10L, TimeUnit.SECONDS);
CompletableFuture.supplyAsync(() -> "someValue", delayed)

There's also an overload where you can specify the Executor to use in place of the "default executor".