groovy for java experts
TRANSCRIPT
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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: [email protected]
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Questions