Nowadays, computer systems (and other related systems, such as tablets or smartphones) allow you to do several tasks at the same time. This is possible because they have concurrent operating systems that control several tasks at the same time. You can also have one application that executes several tasks (read a file, show a message, and read data over a network) if you work with the concurrency API of your favorite programming language. Java includes a very powerful concurrency API that allows you to implement any kind of concurrency applications with very little effort. This API increases the features provided to programmers in every version--now, in Java 8, it has included the Stream API and new methods and classes to facilitate the implementation of concurrent applications. This book covers the most important elements of the Java concurrency API, showing you how to use them in real-world applications. These elements are as follows:

• The Executor framework, to control the execution of a lot of tasks
• The Phaser class, to execute tasks that can be divided into phases
• The fork/join framework, to execute that tasks that solve a problem using the divide and conquer technique
• The Stream API, to process big sources of data, including the new reactive streams
• Concurrent data structures, to store the data in concurrent applications
• Synchronization mechanisms, to organize concurrent tasks

However, the Java concurrency API includes much more--a methodology to design concurrency applications, design patterns, tips and tricks to implement good concurrency applications, the tools and techniques to test concurrency applications, and ways to implement concurrency applications in other languages for the Java Virtual Machine, such as Clojure, Groovy, and Scala.