### Question:
FutureCallbackAdapter extends CompletableFuture<V> implements Callback<V> { @Override public void call(V value) { this.complete(value); }  @Override void call(V value); @Override void callException(Exception ex);  }### Answer:
@Test public void test() throws InterruptedException, ExecutionException, TimeoutException { FutureCallbackAdapter<String> f = new FutureCallbackAdapter<>(); assertFalse(f.isDone()); assertFalse(f.isCancelled()); f.call("test"); assertEquals("test", f.get()); assertEquals("test", f.get(1, TimeUnit.SECONDS)); assertTrue(f.isDone()); assertFalse(f.cancel(true)); assertFalse(f.isCancelled()); }