Java 8 in Action

Introduction

The book "Java 8 in Action" (authors: Raoul-Gabriel Urma, Mario Fusco, Alan Mycroft) was published in 2014 and instantly became a desktop guide for everyone who wanted to master the innovations of the eighth version of Java. This is not just a reference book — it is a full immersion into the functional programming style that changed the approach to writing code in Java. Over 424 pages, the authors sequentially reveal lambda expressions, Streams, Optional, CompletableFuture, and the new Date/Time API.

What the book is about

The book is divided into four parts. The first part introduces the basics of lambda expressions and functional interfaces. The second part — the heart of the book — is dedicated to the Stream API: creation, processing, parallel streams. The third part covers Optional, CompletableFuture, and the new date handling model. The fourth part — "Beyond Java 8" — examines the ideas that laid the foundation for future versions (including reactive programming).

Who this book is for

The book is intended for Java developers of any level who are already familiar with Java syntax (classes, interfaces, inheritance) and want to transition to a modern style. It will be useful both for beginners encountering lambdas for the first time and for experienced programmers wanting to systematize their knowledge of Streams and parallel computing.

What the reader will learn

• How to write lambda expressions and method references
• How to use functional interfaces (Predicate, Function, Consumer, Supplier)
• How to create and process data streams using the Stream API
• How to perform parallel operations with minimal effort
• How to avoid NullPointerException using Optional
• How to write asynchronous code with CompletableFuture
• How to work with the new Date/Time API (LocalDate, LocalTime, ZonedDateTime)
• How to refactor old code using functional approaches
• How to test lambda expressions

Strengths

Practical focus. Each concept is accompanied by code examples that can be tried out immediately. Gradual increase in complexity. The authors start with simple lambdas and gradually lead to complex topics like parallel streams and CompletableFuture. In-depth explanation. The book shows not just "how" but also "why" it works that way — this helps form the right mindset. Relevance. Despite the release of Java 17, the foundations laid in Java 8 remain the bedrock of modern development.

Who it is recommended for

The book is a must-read for everyone who writes in Java and wants to keep up with the times. I especially recommend it to developers transitioning from Java 7 and below, as well as to those who want to understand functional programming in the context of Java. If you are preparing for a Java developer interview — this book will help cover most questions about Java 8.

Conclusion: "Java 8 in Action" is a classic that does not lose its relevance. A clear structure, vivid examples, and the authors' style make it one of the best books on Java 8 on the market.