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September 12, 2009

Groovy Goodness: Parameters with Default Values

In Groovy we can assign default values to parameters in a method. If we define a default value for a parameter Groovy basically supports two method signatures: one with all parameters and one where the parameter with a default value is omitted. If we use multiple parameters with default values then the right most parameter with a default value is first eliminated then the next and so on.

def say(msg = 'Hello', name = 'world') {
    "$msg $name!"
}

// We can invoke 3 signatures:
// say(), say(msg), say(msg, name)
assert 'Hello world!' == say()
// Right most parameter with default value is eliminated first.
assert 'Hi world!' == say('Hi')
assert 'Howdy, mrhaki!' == say('Howdy,', 'mrhaki')

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