Lesson 12 - Multithreading in Java - CompletableFuture
In the previous lesson, Multithreading in Java - ForkJoinPool, we talked about
ForkJoinPool
. In this lesson, we're going to learn what is in my
opinion the best class for parallel programming offered by the basic Java
Concurrency framework - CompletableFuture
.
A few lessons back, we introduced different interfaces related to parallel
programming: Runnable
, Callable
, and
Future
. The interfaces are ordered according to the increasing
functionality. We described the Future
interface as an object that
will contain the result of a task sometime in the future. The problem with this
interface is that we don't know when the result will be available. The only way
to get the result is to use the blocking get()
method, which blocks the thread in which it's called. The developers tried to
solve this problem by using the CompletableFuture
class and I must
say that they did great. Let's introduce CompletableFuture
.
CompletableFuture
Right at the beginning I have to say that if you know something about reactive programming, you will feel at home. Alternatively, you can find many similarities to the promises from JavaScript.
The class implements two interfaces:
...End of the preview...

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In this tutorial, we'll introduce advanced techniques for parallel programming in Java. Let's describe CompletableFuture.
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