Book Image

Mastering Concurrency Programming with Java 9 - Second Edition

By : Javier Fernández González
Book Image

Mastering Concurrency Programming with Java 9 - Second Edition

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. Java 9 includes a comprehensive API with lots of ready-to-use components for easily implementing powerful concurrency applications, but with high flexibility so you can adapt these components to your needs. The book starts with a full description of the design principles of concurrent applications and explains how to parallelize a sequential algorithm. You will then be introduced to Threads and Runnables, which are an integral part of Java 9's concurrency API. You will see how to use all the components of the Java concurrency API, from the basics to the most advanced techniques, and will implement them in powerful real-world concurrency applications. The book ends with a detailed description of the tools and techniques you can use to test a concurrent Java application, along with a brief insight into other concurrency mechanisms in JVM.
Table of Contents (21 chapters)
Title Page
About the Author
About the Reviewer
Customer Feedback


In this chapter, we used the different versions of the collect() method provided by the Stream framework to transform and group the elements of a Stream. This and Chapter 8, Processing Massive Datasets with Parallel Streams - the Map and Reduce Model, teach you how to work with the whole stream API.

Basically, the collect() method needs a collector that processes the data of the stream and generates a data structure returned by the set of aggregate operations that forms the stream. A collector works with three different data structures-the class of the input elements, an intermediate data structure used while processing the input elements, and a final data structure that is returned.

We used the different versions of the collect() method to implement a search tool that must look for a query in a set of files without an inverted index, a recommendation system, and a tool to calculate the common contacts between two users in a social network.

In the next chapter, we will take a deep look...