Maurice Naftalin - Mastering Lambdas: Java Programming in a Multicore World

Copyright 2015 by Maurice Naftalin. All rights reserved. Except as permitted under the United States Copyright Act of 1976, no part of this publication may be reproduced or distributed in any form or by any means, or stored in a data base or retrieval system, without the prior written permission of the publisher.

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To my boys: Joe, Isaac, Daniel, and Ben

Maurice Naftalin has over 30 years experience in IT as a developer, designer, architect, manager, teacher, and author. Naftalin, a certified Java programmer, has worked in every release of Java to date. His experience in Java and business gives him a unique perspective on the fundamental change that comes with introducing lambda expressions in Java SE 8. Naftalin is a frequent presenter at conferences worldwide, including the annual JavaOne. He runs a popular tutorial site in collaboration with Oracles development team, www.lambdafaq.org, focused on the new language features in Java 8.

About the Technical Editors

Stuart Marks works on the JDK Core Libraries team in the Java Platform Group at Oracle. He is currently working on lambda, streams, and collections, as well as improving test quality and performance. He has previously worked on JavaFX and Java ME at Sun Microsystems. He has over 20 years of software platform product development experience in the areas of window systems, interactive graphics, and mobile and embedded systems. Stuart holds a masters degree in Computer Science and a bachelors degree in Electrical Engineering from Stanford University. He lives with his wife and daughter in California.

Brian Goetz is one of the leading authorities on Java programming. He is the author of the very successful Java Concurrency in Practice, as well as over 75 articles on Java development. He was the specification lead for JSR-335 (Lambda Expressions for the Java Language) and has served on numerous other JCP Expert Groups. Brian is the Java Language Architect at Oracle.

J ava SE 8 may well represent the largest change ever to the Java language and libraries. Since youre reading a book called Mastering Lambdas, you probably already know that the biggest new feature is the addition of lambda expressions. Depending on your perspective, this evolution began in 2009 (when Project Lambda was launched), or 2006 (when several proposals were made for adding closures to Java), or 1997 (when inner classes were added), or 1941 (when Alonzo Church published his foundational work on the theory of computing, from which lambda expressions get their name).

However long it took to get here, its about time! While it may initially appear that lambda expressions are just another language feature, in reality, they will change the way you think about programming, offering a powerful new tool for applying abstraction to the programming challenges you face every day. Of course, Java already gives us powerful tools for abstraction, such as inheritance and generics, but these are largely about abstracting over data. Lambda expressions complement these by giving us a better tool for abstracting over behavior.

In embracing lambda expressions, Java has taken a mild turn towards functional programming. While it might seem that object-oriented programming and functional programming are competing disciplines, they offer us complementary tools for managing program complexity. And, as hardware parallelism continues to increase, the building blocks of functional programmingimmutable values and pure functionsbecome even more effective tools for managing that complexity.