Listenablefuture vs Completablefuture

Ashutosh Jha :

I tried hard but didn't find any article or blog which clearly compares ListenableFuture and CompletableFuture, and provides a good analysis.

So if anyone can explain or point me to such a blog or article, it will be really good for me.

Livia Moroianu :

Both ListenableFuture and CompletableFuture have an advantage over its parent class Future by allowing the caller to "register" in one way or another a callback to be called when the async action has been completed.

With Future you can do this:

ExecutorService executor = ...;
Future f = executor.submit(...);
f.get();

f.get() gets blocked until the async action is completed.

With ListenableFuture you can register a callback like this:

ListenableFuture listenable = service.submit(...);
    Futures.addCallback(listenable, new FutureCallback<Object>() {
                @Override
                public void onSuccess(Object o) {
                    //handle on success
                }

                @Override
                public void onFailure(Throwable throwable) {
                   //handle on failure
                }
            })

With CompletableFuture you can also register a callback for when the task is complete, but it is different from ListenableFuture in that it can be completed from any thread that wants it to complete.

CompletableFuture completableFuture = new CompletableFuture();
    completableFuture.whenComplete(new BiConsumer() {
        @Override
        public void accept(Object o, Object o2) {
            //handle complete
        }
    }); // complete the task
    completableFuture.complete(new Object())

When a thread calls complete on the task, the value received from a call to get() is set with the parameter value if the task is not already completed.

Read about CompletableFuture