Hidden features of Groovy?

2018-06-15 01:53:51

It seems like Groovy was forgotten in this thread so I'll just ask the same question for Groovy.

Try to limit answers to Groovy core

One feature per answer

Give an example and short description of the feature, not just a link to documentation

Label the feature using bold title as the first line

See also:

Hidden features of Python

Hidden features of Ruby

Hidden features of Perl

Hidden features of Java

Using the spread-dot operator

def animals = ['ant', 'buffalo', 'canary', 'dog']
assert animals.size() == 4
assert animals*.size() == [3, 7, 6, 3]

This is a shortcut for animals.collect { it.size() } .

The with method allows to turn this:

 myObj1.setValue(10)
 otherObj.setTitle(myObj1.getName())
 myObj1.setMode(Obj1.MODE_NORMAL)

into this

 myObj1.with {
    value = 10
    otherObj.title = name
    mode = MODE_NORMAL
 }

Using hashes as pseudo-objects.

def x = [foo:1, bar:{-> println "Hello, world!"}]
x.foo
x.bar()

Combined with duck typing, you can go a long way with this approach. Don't even need to whip out the "as" operator.

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