Thread pools

In this section, we will look into the Executor interfaces and their implementations provided in the java.util.concurrent package. They encapsulate thread management and minimize the time an application developer spends on the writing code related to threads' life cycles.

There are three Executor interfaces defined in the java.util.concurrent package:

• The base Executor interface has only one void execute(Runnable r) method in it. It basically replaces the following:

Runnable r = ...;
(new Thread(r)).start()

However, we can also avoid a new thread creation by getting it from a pool.

• The ExecutorService interface extends Executor and adds four groups of methods that manage the life cycle of the worker threads and of the executor itself:
• Methods submit(): Place in the queue for the execution of an object of the interface Runnable or interface Callable (allows the worker thread to return a value); return object of Future interface, which can be used to access the value returned by the...