Listenablefuture vs Completablefuture

Question

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.

Answer 1

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