Dierk König - Groovy in Action: Covers Groovy 2.4

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To our families

For anyone considering Groovy, or just interested in seeing what all of the fuss is around the features of dynamic languages, this book will deliver.

Gregory Pierce, JavaLobby.org

Not just a language guide, this book presents the clear, readable, and enjoyable specification of Groovy ... you should definitely read it.

Alexander Popescu, Mindstorm

A real page-turner. Brilliant examples ... all other programming books I know really fall behind.

Dr. Gernot Starke

Excellent code samples ... very readable.

Scott Shaw, ThoughtWorks

Great, logical focus on language features.

Norman Richards, author of XDoclet in Action

Destined to be the definitive guide. First rate!

Glen Smith, Bytecode Pty Ltd.

Examples are clear, complete, and they work!

David Sills, JavaLobby.org

Among the top five Manning books. For me personally, its also a perception-changing and influential book.

Weiqi Gao

The examples are the strongest part of the bookall assumptions are checked using assertions, and they have been run before printing so one can trust that theyre faultless. Explanations are fine-grained so even inexperienced developers can read it with understanding.

Marek Zganiacz, Comarch SA

Very readable, engaging, and does a great job of slotting Groovy into the broader world of software development. Highly recommended.

Pan Pantziarka

Real computer LITERATURE.

Johannes Link

I first integrated Groovy into a project I was working on almost two years ago. There is a long and rich history of using scripting languages as a flexible glue to stitch together, in different ways, large modular components from a variety of frameworks. Groovy is a particularly interesting language from this tradition, because it doesnt shy away from linguistic sophistication in the pursuit of concise programming, especially in the areas around XML, where it is particularly strong. Groovy goes beyond the glue tradition of the scripting world to being an effective implementation language in its own right. In fact, while Groovy is often thought of and referred to as a scripting language, it really is much more than that.

It is traditional for scripting languages to have an uneasy relationship with the underlying linguistic system in which the frameworks are implemented. In Groovys case, they have been able to leverage the underlying Java model to get integration that is smooth and efficient. And because of the linguistic similarities between Java and Groovy, it is fairly painless for developers to shift between programming in one environment and the other.

Groovy in Action by Dierk Knig and his coauthors is a clear and detailed exposition of what is groovy about Groovy. Im glad to have it on my bookshelf.

J AMES G OSLING C REATOR OF J AVA D ECEMBER 2006

Nothing is more terrible than ignorance in action.

Johann Wolfgang von Goethe

Thinking back to January 2007 when the first edition of this book hit the shelves, feels like time travel to the Middle Ages. The idea of using a programming language other than Java on the Java platform was widely considered frivolous. Today, a new language seems to pop up every other week, and we even go as far as designing languages for specific domains (DSLs) on a per-project basis.

This evolution of languages reflects a change in concerns. If performance were still our utmost concern, we would all be coding in a low-level language. But if performance is considered good enough for our purposes, we now turn our focus on human approachability.

Groovy has been a trendsetter for this development. Many Groovy features that ease the burden of developers are now commonplace in novel languages and may even find their way into newer versions of Java: literal declarations for common datatypes, simplified property access, null-safe dereferencing, closures, and more. Surprisingly many languages have adopted Groovys optional typing strategyfew languages can claim to have static and dynamic behavior at the same time, though, the way Groovy has since version 2.

Just like Groovy, the first edition of this book set some trends as well. The idea of having every single listing as a self-testing piece of code resonated in the market and may be one reason why the book is among Mannings top-ten bestsellers of the decade.

The feedback for the first edition was overwhelming. We never expected to have so many great developers speaking so nicely about our work. We have no words to express this feeling of being proud and humbled at the same time. Most touching, though, was the stranger who once gave Dierk a pat on the back and mumbled, Thank you for the book! and then disappeared into the crowd. This book is for him.

We are fully aware that the first edition would have never been so successful if Groovy itself had been less appealing. The reason for Groovys success is easy to see: it delivers its power in the most Java-friendly manner. It is Javas dynamic friend.

The development of Groovy, from version 1.0 covered in the first edition of this book until the current version 2.4, has closed what used to be a syntax gap by providing enums, annotations, generics, the classic for loop, nested classes, varargs, static imports, and the ability to use Groovy closures where Java 8 expects lambda expressions.