What is Executorcompletionservice in Java?
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.
What is ExecutorService Java?
ExecutorService is a JDK API that simplifies running tasks in asynchronous mode. Generally speaking, ExecutorService automatically provides a pool of threads and an API for assigning tasks to it.
How do you use ExecutorService with CompletableFuture?
The CompletableFuture API allows to easily chain more calls with thenApply() , thenCompose() etc. It is thus more flexible than the simple Future returned by ExecutorService. submit() ; Using CompletableFuture allows to easily return a future from your child() method using return CompletableFuture.
What is runnable and Callable?
Runnable is the core interface provided for representing multi-threaded tasks and Callable is an improved version of Runnable that was added in Java 1.5.
Why do we use Callable?
A callable interface was added in Java 5 to complement the existing Runnable interface, which is used to wrap a task and pass it to a Thread or thread pool for asynchronous execution. Callable actually represents an asynchronous computation, whose value is available via a Future object.
Does CompletableFuture use thread pool?
CompletableFuture executes these tasks in a thread obtained from the global ForkJoinPool. commonPool(). But we can also create a Thread Pool and pass it to runAsync() and supplyAsync() methods to let them execute their tasks in a thread obtained from our thread pool.
What is the difference between future and CompletableFuture?
Future vs CompletableFuture. CompletableFuture is an extension to Java’s Future API which was introduced in Java 5. A Future is used as a reference to the result of an asynchronous computation.