What can be submitted to ExecutorService?

An ExecutorService should be shut down once it is no longer needed to free up system resources and to allow graceful application shutdown . Because the threads in an ExecutorService may be nondaemon threads, they may prevent normal application termination.

The executor service creates and maintains a reusable pool of threads for executing submitted tasks . The service also manages a queue, which is used when there are more tasks than the number of threads in the pool and there is a need to queue up tasks until there is a free thread available to execute the task.

Submit Runnable The Java ExecutorService submit(Runnable) method also takes a Runnable implementation, but returns a Future object. This Future object can be used to check if the Runnable has finished executing.

The newSingleThreadExecutor() method of Executors class creates an Executor that uses a single worker thread operating off an unbounded queue . (Note however that if this single thread terminates due to a failure during execution before the shutdown, a new one will take its place if needed to execute subsequent tasks.).

ExecutorService executor = Executors. newCachedThreadPool(); When you instantiate your Executor Service, a few parameters are initialized. Depending on how you instantiated your Executor Service, you may manually specify these parameters or they may be provided for you by default.23 Mar 2018

The Java ExecutorService is a construct that allows you to pass a task to be executed by a thread asynchronously . This service creates and maintains a reusable pool of threads for executing submitted tasks.23 May 2021

A simple program of Java ExecutorService