Venkat Subramaniam - Programming Groovy 2: Dynamic Productivity for the Java Developer

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To Mythili and Balufor being much more than an aunt and an unclefor being there when I needed them most.

As the saying goes, time flies. In the first edition of this book, Venkat guided you through all the nice features of Groovy 1.5 and turned you into a proficient Groovy-ist, but its now time to discover what Groovy 2 has in store. Of course, your favorite author has you covered!

The Groovy team worked on three major themes for the 2.0 version. First of all, we brought Groovy in line with JDK 7: we added the Java 7 Project Coin syntax enhancements, and we also powered Groovys runtime with the invoke dynamic bytecode instruction and APIs under the hood. That way, you can use the latest syntax additions in Groovy even on older JDKs, but by running JDK 7 youll benefit from performance improvements.

Secondly, we broke up Groovy into smaller modules, a core and several API-related ones, so you can pick the pieces you are interested in to compose your application. We also extended the Groovy Development Kit to allow you to create your own extension methodsjust like Groovy does with its enriched JDK with the famous DefaultGroovyMethods class!

Last but not least, we introduced a static theme with two key novelties: static type-checking and static compilation. With the former, you can catch typos and other errors easily at compile time and even allow your domain-specific languages to be type-checked, while with the latter you can get the same performance as Java for critical parts of your application that request the highest level of speed.

With all those additions to the language and APIs, Groovy continues to mature like good wine, and just as a sommelier would share his expertise, Venkat dispenses his knowledge of all the power features of Groovy through the nice flavors of the chapters you are going to read, helping you get up to speed with the language and transport you to the next level.

The Java platform is arguably one of the most powerful and widely adopted ecosystems today. It has three significant pieces:

• The Java Virtual Machine (JVM), which has become increasingly powerful and more performant over the years

• The Java Development Kit (JDK), the rich set of third-party libraries and frameworks that help us effectively leverage the power of the platform

• The set of languages on the JVMthe Java language being the firstthat help us program the platform

Languages are like vehicles that let us navigate the platform. They let us reach into various parts of this landscape with ease. The Java language has come a long way; its libraries have been refactored and expanded. Its gotten us this far, but we need to look beyond the Java language to languages that are lightweight and that can make us more productive. When used correctly, dynamic languages, the functional style of programming, and metaprogramming capabilities can help us navigate the landscape much faster. When viewed as vehicles, these newer languages arent faster cars; theyre flying machines, giving us the capability to be several orders of magnitude more productive.

The Java language has been flirting with metaprogramming and the functional style of programming for a while and will support some of these features to various degrees in future versions. We dont have to wait for that day, however. We can build performant JVM applications with all the dynamic capabilities today, right now, using Groovy.

Merriam-Webster defines groovy as marvelous, wonderful, excellent, hip, trendy. The Groovy language is all of thatits lightweight, low-ceremony, dynamic, object-oriented, and runs on the JVM. Groovy is open sourced under the Apache License, version 2.0.It derives strength from various languages, such as Smalltalk, Python, and Ruby, while retaininga syntax familiar to Java programmers. Groovy compiles into Java bytecode and extends theJava API and libraries. It runs on Java 1.5 and newer. For deployment, all we need is a Groovy Java archive (JAR) in addition to the regular Java stuff, and were all set.