Java 8 introduced a wealth of new features, pushing Java towards the so-called functional programming paradigm. Benefits from this shift include succinctness and ease of developing robust multi-threaded applications.

In this course, we will introduce the key functional features of Java 8 and 9, and explain how they can be used to write code that is more expressive and easily amenable to parallelization.

Specifically, we will first discuss lambda functions and functional interfaces. Using these features, programmers can easily create objects that offer a single specific service, similarly to anonymous classes. We will also explore the predefined functional interfaces that can be found in the Java API, starting from well-known pre-existing ones like Comparator and Runnable.

Reaping the full benefits of lambda functions requires employing them with streams, a new kind of collection with built-in parallelization support. We will examine the relationship between streams and collections, and how the latter have changed as a result of the new language features.

Finally, after having mastered the key features of streams, we will consider the details related to parallel execution, such as the crucial notion of side-effect and the fork-join execution model.