What is the use of future in Java?

The Callable object returns a Future object which provides methods to monitor the progress of a task being executed by a thread. The future object can be used to check the status of a Callable and then retrieve the result from the Callable once the thread is done. It also provides timeout functionality.

How does a Java Future work?

Future , represents the result of an asynchronous computation. When the asynchronous task is created, a Java Future object is returned. … In the case of the ExecutorService , it returns a Future when you submit a Callable for it to execute concurrently (asynchronously).

What does Future get do?

The future. get() method blocks and waits for the task to complete. If you call an API from a remote service in the callable task and the remote service is down, then future. get() will block forever, which will make the application unresponsive.

What is the use of Future interface?

The Future interface is an interface that represents a result that will eventually be returned in the future. We can check if a Future has been fed the result, if it’s awaiting a result or if it has failed before we try to access it, which we’ll cover in the upcoming sections. The get() method retrieves the result.

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How can I use FutureTask and Future in Java?


  1. FutureTask implementation Future interface and RunnableFuture Interface, means one can use FutureTask as Runnable and can be submitted to ExecutorService for execution.
  2. When one call Future. …
  3. FutureTask acts like a latch.
  4. Computation represent by FutureTask is implemented with Callable interface.

Does Java have future?

Java has and will continue to have a very good future. Software that solves specific purposes like ERP, CRMs, cloud internal software, Orchestration frameworks, IDMs, etc, have been built using Java. Since this has taken years to build them they will continue to use them now and in the future.

What is the difference between future and CompletableFuture?

CompletableFuture is used for asynchronous programming in Java. … A Future is used as a reference to the result of an asynchronous computation. It provides an isDone() method to check whether the computation is done or not, and a get() method to retrieve the result of the computation when it is done.

Does Future get () block?

Yes, documentation of Future. get() says: Waits if necessary for the computation to complete, and then retrieves its result. so, it will block until results of computation are available, or the computation was interrupted (cancelled or resulting in exception).

How can I use Future?

Future. get() is used to retrieve the result of computation.

You have a couple of options:

  1. call isDone() and if the result is ready ask for it by invoking get() , notice how there is no blocking.
  2. block indefinitely with get()
  3. block for specified timeout with get(long timeout, TimeUnit unit)
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What is the Future class in Java?

Simply put, the Future class represents a future result of an asynchronous computation – a result that will eventually appear in the Future after the processing is complete. Let’s see how to write methods that create and return a Future instance.

What is callable and Future in Java?

Observe that Callable and Future do two different things – Callable is similar to Runnable, in that it encapsulates a task that is meant to run on another thread, whereas a Future is used to store a result obtained from a different thread.

How do you use Future in Vertx?

Best Java code snippets using io.vertx.core.Future.compose (Showing top 20 results out of 432)

  1. Future.succeededFuture()
  2. Future.future()
  3. Throwable t;Future.failedFuture(t)
  4. Smart code suggestions by Tabnine.

What is ExecutorCompletionService in Java?

Class ExecutorCompletionService<V>

A CompletionService that uses a supplied Executor to execute tasks. This class arranges that submitted tasks are, upon completion, placed on a queue accessible using take . The class is lightweight enough to be suitable for transient use when processing groups of tasks.

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