Learning a new programming language is comparable to learning to speak a foreign language. You have to deal with new vocabulary, grammar, and language idioms. This initial effort pays off multiple times, however. With the new language, you find unique ways to express yourself, you are exposed to new concepts and styles that add to your personal abilities, and you may even explore new perspectives on your world. This is what Groovy did for us, and we hope Groovy will do it for you, too.
The first part of this book introduces you to the language basics: the Groovy syntax, grammar, and typical idioms. We present the language by example as opposed to using an academic style.
You may skim this part on first read and revisit it before going into serious development with Groovy. If you decide to skim, please make sure you visit chapter 2 and its examples. They are cross-linked to the in-depth chapters so you can easily look up details about any topic that interests you.
One of the difficulties of explaining a programming language by example is that you have to start somewhere. No matter where you start, you end up needing to use some concept or feature that you haven’t explained yet for your examples. Section 2.3 serves to resolve this perceived deadlock by providing a collection of self-explanatory warm-up examples.
We explain the main portion of the language using its built-in datatypes and introduce expressions, operators, and keywords as we go along. By starting with some of the most familiar aspects of the language and building up your knowledge in stages, we hope you’ll always feel confident when exploring new territory.
Chapter 3 introduces Groovy’s typing policy and walks through the text and numeric datatypes that Groovy supports at the language level.
Chapter 4 continues looking at Groovy’s rich set of built-in types, examining those with a collection-like nature: ranges, lists, and maps.
Chapter 5 builds on the preceding sections and provides an in-depth description of the closure concept.
Chapter 6 touches on logical branching, looping, and shortcutting program execution flow.
Finally, chapter 7 sheds light on the way Groovy builds on Java’s objectoriented features and takes them to a new level of dynamic execution.
At the end of part 1, you’ll have the whole picture of the Groovy language. This is the basis for getting the most out of part 2, which explores the Groovy library: the classes and methods that Groovy adds to the Java platform. Part 3, titled “Everyday Groovy,” will apply the knowledge obtained in parts 1 and 2 to the daily tasks of your programming business.