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Groovy for Java experts

Václav PechSoftware Developer and Product Evangelist

JetBrains, Inc.

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Properties

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Closures

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Closures – implicit parameter

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Iterations

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GDK = JDK + FUN• java.util.Collection

– each(), find(), join(), min(), max() …

• java.lang.Object– any(), every(), print(), invokeMethod(), …

• java.lang.Number– plus(), minus(), power(), upto(), times(), …

• …

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Some operators

• [‘Java’, ‘Groovy’]*.toUpperCase()

• customer?.shippingAddress?.street

• return user.locale ?: defaultLocale

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Syntax enhancements• Dynamic (duck) typing – optional!• GDK• Syntax enhancements

– Properties– Closures– Named parameters – Collections and maps– Operator overloading– …

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Enjoy writing tests• For both Java and Groovy• Run with Ant, Maven, IDE, …• Integrated JUnit support

• assert…(), shouldFail(), …• Relaxed typing• Easy mocking

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Big Boy Toys• Scripting

• Builders

• Domain Specific Languages

• Meta-programming

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Scripting• Evaluate custom Groovy code

At run-time!!!

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Builders• Construct hierarchies

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Builders - GAnt

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Builders – Spring config

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Categories

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DSL• Limited purpose language• Targeted to a particular domain• Friendlier API to a framework

– External• SQL, HTML, CSS, …

– Internal

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DSL – Date manipulation

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DSL – Hibernate criteria

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DSL – Account manipulation

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Dynamic method invocation

GroovyObjectinvokeMethod()getProperty()setProperty()

methodMissing()propertyMissing()

MetaClass

invokeMethod()

propertiesmethods

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SummaryGroovy

Powerful Java extension

Tests, Builders, Scripting, DSLs

– Contact me: vaclav@jetbrains.com

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Questions