Groovy Documentation IBM Practically Groovy

Shebang:

#!/usr/bin/env groovy
println "Hallo Sandy!"

A script automatically creates a class which has the same name as the filename of the script:

#!/usr/bin/env groovy
// Filname: groovytest
println this.class      // prints: class groovytest
println getClass()      // prints: class groovytest
println this.getClass() // prints: class groovytest

The first version is a class literal. println seems to call implizitely toString() on any object. (This is the same as System.out.println() in standard java.):

println this.class            // prints: class groovytest
println this.class.toString() // prints: class groovytest

The parent class of the autogenerated script class is groovy.lang.Script:

println this.class.getSuperclass() // prints: groovy.lang.Script

println() is a method of the autogenerated script class (inherited from groovy.lang.Script). It can be called without this. and braces. This seems to be added automatically, because the following call prints: …Exception: No signature of method: groovytest.println() is applicable for argument types: (java.lang.Integer, java.lang.Integer)…

#!/usr/bin/env groovy
// Filename: groovytest
println 0,0

#!/usr/bin/env groovy
myList = [1976, 1969] // create a list
myList << 2010        // append something to the end
println myList        // => [1976, 1969, 2010]
println myList[2]     // => 2010
println myList[3]     // => null
println myList.size   // => 3
println myList.class  // => class java.util.ArrayList

Each list creates an implementation of java.util.List. Hence the complete API of List is available:

println myList.get(0) // => 1976
println myList.size() // => 2

More on lists: usage examples, added methods to the standard List interface

• Interfaces can be implemted using closures and maps
• .sort() is a method added to Collection by Groovy
• Everything can be traversed using each
• Getters and setters are autogenerated
• def is used for dynamically typed variables. See Scoping+and+the+Semantics+of+"def" → What is this „def“ I heard of?

• Named arguments are possible. Are they useful?
• Final classes can be extended