Scala for Java developers : build reactive, scalable applications and integrate Java code with the power of Scala

282 Pages·2014·3.9 MB·English

by  Alexandre

Scala for Java Developers
Build reactive, scalable applications and integrate Java
code with the power of Scala
Thomas Alexandre
BIRMINGHAM - MUMBAI
Scala for Java Developers
Copyright © 2014 Packt Publishing
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First published: April 2014
Production Reference: 2230414
Published by Packt Publishing Ltd.
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ISBN 978-1-78328-363-7
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Cover Image by Grégoire Alexandre ([email protected])
Credits
Author Copy Editors
Thomas Alexandre Roshni Banerjee
Deepa Nambiar
Reviewers
Carlos Estebes Alfida Paiva
Tomer Gabel Stuti Srivastava
Eric Le Goff Laxmi Subramanian
Steve Perkins Sayanee Mukherjee
Erik Wallin
Project Coordinator
Akash Poojary
Commissioning Editor
Kunal Parikh
Proofreaders
Acquisition Editors Simran Bhogal
Rubal Kaur Paul Hindle
Neha Nagwekar
Maria Gould
Content Development Editors Stephen Copestake
Neil Alexander
Indexer
Larissa Pinto
Monica Ajmera Mehta
Technical Editors
Miloni Dutia Graphics
Ronak Dhruv
Kunal Anil Gaikwad
Kapil Hemnani
Production Coordinator
Mukul Pawar Nilesh Bambardekar
Cover Work
Nilesh Bambardekar

Foreword
I wish this book had been available when I first started my own Scala journey.
As a Java developer, you must have heard a lot about Scala, even if you haven't yet
written any Scala code. You must have noticed that Scala is becoming popular and
heard vigorous debate about it. As I sat down to write this, I typed "scala is" into
Google. The top completions included "scala is awesome", "scala is too complex", and
"scala is hard." Understandably, you may be confused by such polarization. You may
also have heard arcane, possibly off-putting details about obscure Scala idioms and
advanced functional programming.
What you probably have not heard is a methodical, impartial attempt to answer
questions such as "might Scala make me more productive in my daily work?",
"will it be easy for me to pick up Scala?", and ultimately, "Should I switch from
Java to Scala?".
Given the size of the Java community and the quality and ubiquity of the JVM,
these are vital questions for many of us as developers and to our industry as a whole.
Author Thomas Alexandre directly addresses them, presenting solid evidence in
the form of working code. He shows that "Scala is awesome", if "awesome" means
providing elegant solutions to common, real world problems. He shows that "Scala
is not hard" by listing the straightforward steps to each of those solutions. He shows
how Scala code is usually less complex than the familiar Java code to solve the same
problem. He equips you to answer the question of whether you want to switch from
Java to Scala.
The focus is on solving practical problem, and not on evangelizing language features
for its own sake. Thomas explains core concept, such as functional programming,
which may be relatively unfamiliar to Java developers, but his main emphasis is
building on what the reader already knows. He does all this without a hint of the
programming language chauvinism that often causes language debates to shed
more heat than light.
The topics covered are all relevant to everyday Java development. Naturally, there
is material that is purely Scala related, such as the coverage of REPL (the Scala
interactive interpreter that has no Java equivalent). However throughout the book,
the emphasis is on how to use Scala to provide better solutions to familiar problem,
such as accessing relational data from Java. The coverage of Scala/Java integration is
particularly welcome, as the topic seldom gets the attention it deserves. (In fact, Scala
is so important partly because it does not force developers to abandon Java and the
JVM). The material is up to date: for example, in its coverage of new but important
technologies such as Typesafe Activator.
After reading this book, you will be ready to decide for yourself whether Scala is for
you. Like Thomas and myself, you may well decide to program in Scala rather than
Java when you have a choice. You will then be eager to learn more about functional
programming and advanced Scala syntax, and you'll be ready for a more conceptual,
reference-oriented book like Martin Odersky's Programming in Scala.
Thomas Alexandre provides the perfect starter to whet the appetite of Java
developers for the rich main course that Scala has to offer. Bon appetit!
Rod Johnson
Creator of Spring framework
Co-founder of SpringSource
About the Author
Thomas Alexandre is a senior consultant at DevCode, specializing in Java and
Scala software development. He is passionate about technology, enthusiastic about
sharing knowledge, and is always looking for ways to code more effectively through
the adoption of new open source software and standards. In addition to 15 years of
Java development, he has focused these past few years on emerging languages and
web frameworks such as Groovy and Scala. He also has a Ph.D. in Computer Science
from the University of Lille, France, and has spent two years as a postdoc with
Carnegie Mellon University in the fields of Security and E-commerce.
Thomas is a certified trainer by Typesafe, the creators of Scala.
Acknowledgments
There are many people who have contributed to this book in one form or another
and I would like to thank them for their help.
First, I would like to thank Martin Odersky, the creator of Scala and co-founder
of Typesafe for inspiring me through his fantastic lectures and two online courses
to write this book. The online courses were written together with Erik Meijer and
Roland Kuhn who are also to be thanked. I am also grateful to many Typesafe
employees as well as Zengularity for creating and enhancing such amazing
technologies. In particular, I would like to thank Viktor Klang and Jonas Bonér
for their numerous tweets with links to great reading material and conference talks.
Thanks to Heiko Seeberger and Trond Bjerkestrand for certifying me as a Typesafe
Trainer for their Fast Track to Scala course.
A big thank you to the very active Scala Community for all their contributions in
terms of open source projects, talks at user groups, and workshops. The meetups at the
Stockholm Scala User Group have been a good source of inspiration as well, thanks.
The team at Packt Publishing has been very helpful and has done a great job at all
levels in reviewing and producing this book. In particular, I would like to thank Akash
Poojary, Neha Nagwekar, Neil Alexander, Miloni Dutia, Kunal Gaikwad, Mukul Pawar,
Kunal Parikh, Rubal Kaur, Apeksha Chitnis, Larissa Pinto, Tomer Gabel, Steve Perkins,
Eric Le Goff, and Sumeet Sawant for their extensive participation.
Thank you to my employer and awesome colleagues at DevCode for all the
encouragement they have given me. Special thanks go to my colleague Erik Wallin
for putting much effort into technical review and producing very useful feedback
under a tight schedule. Thank you to all my great friends and ex-colleagues as well
for their support.
Finally, I would like to thank my family. My parents have always supported me in
everything I have been doing and I would like to thank them for that. I would like to
thank my lovely wife Malin and awesome kids Valdemar (four years old) and Edvin
(three years old) for their great patience and encouragement. Thank you to my
parents-in-law for watching after the kids many a times during the writing of
this book.
Also, a big thank you to my talented brother Grégoire for realizing this terrific
cover picture.
I would like to express my sincere gratitude to Rod Johnson, creator of the Spring
framework and co-founder of SpringSource, for his foreword.