Book Image

Mastering Concurrency Programming with Java 8

By : Javier Fernández González
Book Image

Mastering Concurrency Programming with Java 8

By: Javier Fernández González

Overview of this book

Concurrency programming allows several large tasks to be divided into smaller sub-tasks, which are further processed as individual tasks that run in parallel. All the sub-tasks are combined together once the required results are achieved; they are then merged to get the final output. The whole process is very complex. This process goes from the design of concurrent algorithms to the testing phase where concurrent applications need extra attention. Java includes a comprehensive API with a lot of ready-to-use components to implement powerful concurrency applications in an easy way, but with a high flexibility to adapt these components to your needs. The book starts with a full description of design principles of concurrent applications and how to parallelize a sequential algorithm. We'll show you how to use all the components of the Java Concurrency API from basics to the most advanced techniques to implement them in powerful concurrency applications in Java. You will be using real-world examples of complex algorithms related to machine learning, data mining, natural language processing, image processing in client / server environments. Next, you will learn how to use the most important components of the Java 8 Concurrency API: the Executor framework to execute multiple tasks in your applications, the phaser class to implement concurrent tasks divided into phases, and the Fork/Join framework to implement concurrent tasks that can be split into smaller problems (using the divide and conquer technique). Toward the end, we will cover the new inclusions in Java 8 API, the Map and Reduce model, and the Map and Collect model. The book will also teach you about the data structures and synchronization utilities to avoid data-race conditions and other critical problems. Finally, the book ends with a detailed description of the tools and techniques that you can use to test a Java concurrent application.
Table of Contents (18 chapters)
Mastering Concurrency Programming with Java 8
About the Author
About the Reviewers

An introduction to streams

A stream is a sequence of data (it is not a data structure) that allows you to apply a sequence of operations in a sequential or concurrent way to filter, convert, sort, reduce, or organize those elements to obtain a final object. For example, if you have a stream with the data of your employees, you can use a stream to:

  • Count the total number of employees

  • Calculate the average salary of all employees who live in a particular place

  • Obtain a list of the employees who haven't met their objectives

  • Any operation that implies work with all or part of the employees

Streams are greatly influenced by functional programming (the Scala programming language provides a very similar mechanism), and they were thought to work with lambda expressions. A stream API resembles LINQ (short for Language-Integrated Query) queries available in C# language and, to some extent, could be compared with SQL queries.

In the following sections, we will explain the basic characteristics of streams...