Listenablefuture vs Completablefuture
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