
- •brief contents
- •contents
- •foreword
- •preface
- •acknowledgments
- •about this book
- •Roadmap
- •Code conventions and downloads
- •Author Online
- •About the author
- •about the cover illustration
- •1 Why add Groovy to Java?
- •1.1 Issues with Java
- •1.1.1 Is static typing a bug or a feature?
- •1.1.2 Methods must be in a class, even if you don’t need or want one
- •1.1.3 Java is overly verbose
- •1.1.4 Groovy makes testing Java much easier
- •1.1.5 Groovy tools simplify your build
- •1.2 Groovy features that help Java
- •1.3 Java use cases and how Groovy helps
- •1.3.1 Spring framework support for Groovy
- •1.3.2 Simplified database access
- •1.3.3 Building and accessing web services
- •1.3.4 Web application enhancements
- •1.4 Summary
- •2 Groovy by example
- •2.1 Hello, Groovy
- •2.2 Accessing Google Chart Tools
- •2.2.1 Assembling the URL with query string
- •2.2.2 Transmitting the URL
- •2.2.3 Creating a UI with SwingBuilder
- •2.3 Groovy Baseball
- •2.3.1 Database data and Plain Old Groovy Objects
- •2.3.2 Parsing XML
- •2.3.3 HTML builders and groovlets
- •2.4 Summary
- •3 Code-level integration
- •3.1 Integrating Java with other languages
- •3.2 Executing Groovy scripts from Java
- •3.2.1 Using JSR223 scripting for the Java Platform API
- •3.2.2 Working with the Groovy Eval class
- •3.2.3 Working with the GroovyShell class
- •3.2.4 Calling Groovy from Java the easy way
- •3.2.5 Calling Java from Groovy
- •3.3 Summary
- •4 Using Groovy features in Java
- •4.1 Treating POJOs like POGOs
- •4.2 Implementing operator overloading in Java
- •4.3 Making Java library classes better: the Groovy JDK
- •4.4 Cool AST transformations
- •4.4.1 Delegating to contained objects
- •4.4.2 Creating immutable objects
- •4.4.3 Creating singletons
- •4.5 Working with XML
- •4.6 Working with JSON data
- •4.7 Summary
- •5 Build processes
- •5.1 The build challenge
- •5.2 The Java approach, part 1: Ant
- •5.3 Making Ant Groovy
- •5.3.1 The <groovy> Ant task
- •5.3.2 The <groovyc> Ant task
- •5.3.3 Writing your build in Groovy with AntBuilder
- •5.3.4 Custom build scripts with Gant
- •5.3.5 Ant summary
- •5.4 The Java approach, part 2: Maven
- •5.4.2 The GMaven project
- •5.4.3 Maven summary
- •5.5 Grapes and @Grab
- •5.6 The Gradle build system
- •5.6.1 Basic Gradle builds
- •5.6.2 Interesting configurations
- •5.7 Summary
- •6 Testing Groovy and Java projects
- •6.1 Working with JUnit
- •6.1.1 A Java test for the Groovy implementation
- •6.1.2 A Groovy test for the Java implementation
- •6.1.3 A GroovyTestCase test for a Java implementation
- •6.2 Testing scripts written in Groovy
- •6.2.1 Useful subclasses of GroovyTestCase: GroovyShellTestCase
- •6.2.2 Useful subclasses of GroovyTestCase: GroovyLogTestCase
- •6.3 Testing classes in isolation
- •6.3.1 Coerced closures
- •6.3.2 The Expando class
- •6.3.3 StubFor and MockFor
- •6.4 The future of testing: Spock
- •6.4.1 The Search for Spock
- •6.4.2 Test well, and prosper
- •6.4.4 The trouble with tribbles
- •6.4.5 Other Spock capabilities
- •6.5 Summary
- •7 The Spring framework
- •7.1 A Spring application
- •7.2 Refreshable beans
- •7.3 Spring AOP with Groovy beans
- •7.4 Inline scripted beans
- •7.5 Groovy with JavaConfig
- •7.6 Building beans with the Grails BeanBuilder
- •7.7 Summary
- •8 Database access
- •8.1 The Java approach, part 1: JDBC
- •8.2 The Groovy approach, part 1: groovy.sql.Sql
- •8.3 The Java approach, part 2: Hibernate and JPA
- •8.4 The Groovy approach, part 2: Groovy and GORM
- •8.4.1 Groovy simplifications
- •8.5 Groovy and NoSQL databases
- •8.5.1 Populating Groovy vampires
- •8.5.2 Querying and mapping MongoDB data
- •8.6 Summary
- •9 RESTful web services
- •9.1 The REST architecture
- •9.3 Implementing JAX-RS with Groovy
- •9.4 RESTful Clients
- •9.5 Hypermedia
- •9.5.1 A simple example: Rotten Tomatoes
- •9.5.2 Adding transitional links
- •9.5.3 Adding structural links
- •9.5.4 Using a JsonBuilder to control the output
- •9.6 Other Groovy approaches
- •9.6.1 Groovlets
- •9.6.2 Ratpack
- •9.6.3 Grails and REST
- •9.7 Summary
- •10 Building and testing web applications
- •10.1 Groovy servlets and ServletCategory
- •10.2 Easy server-side development with groovlets
- •10.2.1 A “Hello, World!” groovlet
- •10.2.2 Implicit variables in groovlets
- •10.3.2 Integration testing with Gradle
- •10.3.3 Automating Jetty in the Gradle build
- •10.4 Grails: the Groovy “killer app”
- •10.4.1 The quest for the holy Grails
- •10.5 Summary
- •A.1 Installing a JDK
- •A.2 Installing Groovy
- •A.3 Testing your installation
- •A.4 IDE support
- •A.5 Installing other projects in the Groovy ecosystem
- •B.1 Scripts and the traditional example
- •B.2 Variables, numbers, and strings
- •B.2.1 Numbers
- •B.2.2 Strings and Groovy strings
- •B.3 Plain Old Groovy Objects
- •B.4 Collections
- •B.4.1 Ranges
- •B.4.2 Lists
- •B.4.3 Maps
- •B.5 Closures
- •B.6 Loops and conditionals
- •B.6.1 Loops
- •B.6.2 Conditionals
- •B.6.3 Elvis
- •B.6.4 Safe de-reference
- •B.7 File I/O
- •B.8.1 Parsing and slurping XML
- •B.8.2 Generating XML
- •B.8.3 Validation
- •B.9 JSON support
- •B.9.1 Slurping JSON
- •B.9.2 Building JSON
- •index
- •Symbols

Groovy by example
This chapter covers
■Basic Groovy syntax
■Collections and closures
■Using the Groovy JDK
As the previous chapter stated, this book isn’t intended to be an exhaustive reference for Groovy, but a certain minimum level of Groovy proficiency is necessary. While some people learn best through short, simple code examples illustrating each concept, others prefer to see basic concepts combined to solve actual problems. For those who prefer snippets of code for each feature I’ve provided appendix B, a Groovy tutorial arranged by feature.
In this chapter, I’ll instead walk through a few small but non-trivial Groovy examples. Hopefully this will help communicate not only the syntax of the language, but some of the standard Groovy idioms as well. Some of the examples will be used again in other chapters in the book, but are used here as illustrations of basic Groovy practices.
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