Groovy
Download as PPTX, PDF0 likes267 views
This document provides an overview of Groovy and its relationship to Java. It discusses Groovy's history and genesis as a dynamic language for the Java Virtual Machine. The document covers installing Groovy and demonstrates some key features like typing, objects, looping, regular expressions, and closures. It also discusses Grails, Groovy's web framework, and how Grails applications can now be hosted on Google App Engine.
More Related Content
What's hot (20)
Similar to Groovy (20)
Groovy
- 1. Tom Corcoran ¨C OSS Software - May 20091Get excited by coding again!Java History & the JVMGroovy genesis & it¡¯s relation to JavaInstalling GroovyLive demo to compare and contrast Groovy with Java codeGroovy Typing Object & Looping Regular Expressions Groovy Math Goodies+++ Closures MOP MLVMGrails & GAE
- 2. Tom Corcoran ¨C OSS Software - May 20092JavaJavadeveloped by James Gosling released in 1995Java applications compiled to bytecode (.class files) that can run on any Java virtual machine (JVM) regardless of computer architectureVersion History1 (1995), 2(1998), 3(2000), 4(2002), 5(2004), 6(2006)Java 7 due Q1 2010: No closuresJVM->MLVM : the Java platform is changing GroovyJRuby (Ruby implementation) ScalaClojure (Lisp dialect)Rhino (Javascript implementation)JavaFXScript (Sun¡¯s new baby)Jython (Python implementation)
- 3. Tom Corcoran ¨C OSS Software - May 20093GenesisFirst begun in 2004 by James Strachan, lost momentum, project reenergized by Guillaume Laforgewith v1 released in Jan 2007, currently at v1.6.3JSR 241: Groovy is an agile, dynamic programming language for the Java Virtual Machine. Groovy includes features found in Python, Ruby, and Smalltalk, but uses syntax similar to the Java programming languageLike Java, dynamically compiled to Java Virtual Machinebytecode (.class file)As a result seamless 2 way integration with Java code and librariesDeployed as a jar (zip) file
- 4. Tom Corcoran ¨C OSS Software - May 20094Java++Java is a powerful language already, the goal was to add a new Swiss army knife to the Java developer tool belt, to have the agility and expressivenessof a dynamic languageGroovy is ¡°quite literally Java, but without the pain¡±Follows Java semantics, relaxed grammar, derived from java 5Any Java code will run as Groovy: Its superset-of-Java nature means that you can start with a Java file & change its suffix to ¡°.groovy¡±, often Java developers end up with the gradual adoption route which is as designedGDK: extends the JDK (programming tools for Java)Groovyc in addition to javacGroovyDoc in addition to JavaDocMetaprogramming Can extend a program at runtime, including changing the structure of objects, types, and behaviour
- 5. Tom Corcoran ¨C OSS Software - May 20095InstallationDownload zip/windows installer & unpack/installSet GROOVY_HOME environment variable to unpacked locationAdd GROOVY_HOME/bin to your PATH environment variableSet your JAVA_HOME environment variable to point to your JDKGroovy ShellIn a command shell type groovyshRun Groovy codegroovyMyCode.groovyGroovy ConsoleTo run Swing interactive console type GroovyConsole
- 6. Tom Corcoran ¨C OSS Software - May 20096GroovyBean
- 7. Tom Corcoran ¨C OSS Software - May 20097Increase readabilityThis GroovyBean gives the same result with less code noiseThis also illustrates a recurring theme in Groovy: Make common coding conventions simpledef think of defas an alias of "Object"
- 8. must have def / type name
- 9. defindicates that you don't care about the typesemi colon optional
- 10. Tom Corcoran ¨C OSS Software - May 20098TypingGroovy is optionally typed and the Groovy compiler, groovyc, does not perform full type checkingassigning a string to an integer compiles fine, when you try to run you will receive a GroovyCastException exceptionif you call a method that does not exist, you will not get any compilation error, you will get a MissingMethodException at runtimeRule of thumb: use static typing if interfacing with static language code
- 11. Tom Corcoran ¨C OSS Software - May 20099Objects & LoopingEverything is an object in GroovyJava mixes primitive Boolean type and the numeric types - byte, short, int, long, and char, float and double and reference (object) types class types, interface types, and array typesString literals are represented by String objectsLoopingmapA map is a mapping from unique unordered keys to valuesassertProvide expression that you are asserting will be true, otherwise throws AssertionErrornew reserved word
- 12. Tom Corcoran ¨C OSS Software - May 200910Regular ExpressionsGroovy uses the Java regular expression engine but adds some native support sugar~"pattern" expression, which creates a Java Pattern object=~ expressions, which creates a Java Matcher objectSlashy strings, can help with escaping
- 13. Tom Corcoran ¨C OSS Software - May 200911Groovy MathGroovy uses exact, or decimal math for default calculationsThis means that user computations like: 1.1 + 0.1 == 1.2 will return true rather than false (using float or double types in Java returns a result of 1.2000000000000002)To achieve this groovy literals with decimal points are instantiated as java.math.BigDecimal types rather than binary floating point types (Float, Double)Some financial users are big fans of how it does Math and I have heard of one where the actuaries are able to code in it too and do as wellhttp://groovy.codehaus.org/Groovy+Math
- 14. Tom Corcoran ¨C OSS Software - May 200912GoodiesGroovy TruthGroovy provides parsers & slurpers for working with XMLUse XmlSlurper to slurp up a xml file
- 15. Tom Corcoran ¨C OSS Software - May 200913Goodies+Optional parametersto achieve this in Java you have you have to overload methodTrailing array parameter is optionalImplementing interfacesMethod parameters optional
- 16. Tom Corcoran ¨C OSS Software - May 200914Goodies++Safe dereferencingElvis operator is a shortening of Java's ternary operatoryou will still notice the repetition of the name variable, which would violate the DRY principle (Don't Repeat Yourself)
- 17. Tom Corcoran ¨C OSS Software - May 200915ClosuresClosures are pieces of code that can augment, refine or enhance another piece of codeClosures can be passed to methodsGDK Examples
- 18. Tom Corcoran ¨C OSS Software - May 200916MOPFor each Java class and for each Groovy instance, there is an associated meta-class which represents this runtime behavior of your objectsa groovier kind of meta-class is available: the expando meta-classyou can check that a certain method or property is available
- 19. Tom Corcoran ¨C OSS Software - May 200917MLVMnot a silver bullet...Doing at run-time what other languages do at compile time raise the concern of speed of dynamic languagesDynamic languages such as Groovy/JRuby are up to 10 times slower on micro benchmarks due to heavy reflection use, this does not mean overall speed translates to that ratiothe Da Vinci Machine ProjectSun project to prototype the extension of the JVM to add support for dynamic languagesSpecification process JSR-292: Supporting Dynamically Typed Languagesadd a new bytecode, invokedynamic, to bring dynamic language speed closer to 2/3 times of Javamay be included in Java 7http://openjdk.java.net/projects/mlvm/
- 20. Tom Corcoran ¨C OSS Software - May 200918Grails & GAEAs of 14 May 2009 Grails v1.1.1 now supports the Google Application Engine (GAE)GORM had to have wrapper for GAE¡¯s datastore GQLUp to now to Hosting a grails war was about $20 a month Now free hosting of application with 500 MB of persistent storage and enough CPU and bandwidth for about 5 million page views a monthhttp://myapplication.appspot.com
- 21. Tom Corcoran ¨C OSS Software - May 200919ResourcesGroovy http://groovy.codehaus.org Programming Groovy : VenkatSubramaniam Groovy Recipes: Scott Davis Grails http://www.grails.orgThe Definitive Guide to Grails: Graeme Rocher Grails in Action: Glen Smith & Peter Ledbrook
- 22. Tom Corcoran ¨C OSS Software - May 200920The EndComments http://joind.in/event/view/46Local Groovy User Group? http://gugse.com