/idiomatic-groovy

Idiomatic Groovy

General

  • Omit semicolons
// bad
def number = 1;

// good
def number = 1
  • Omit parentheses for single method calls
// bad
println('Hello World!')

// good
println 'Hello World!'
  • Use parentheses for chained method calls

Strings

  • Use string interpolation for concatenation
def lang = 'Groovy'

// bad
println lang + ' rocks!'

// good
println "$lang rocks!"
  • Use triple-quotes for multiline strings


Collections


    

  • Use the - operator for removing all instances of an element
    • 



// bad
['a', null, 'b', null, 'c'].removeAll { it == null }

// better
['a', null, 'b', null, 'c'].findAll { it != null }

// good
['a', null, 'b', null, 'c'] - null


    

  • Use the + operator for concatenation
    • 



// bad
def l = ['a', 'b', 'c']
l.addAll ['d', 'e', 'f']

// good
l + ['d', 'e', 'f']


Functional Programming


    

  • Use findAll for filtering collections
    • 



// bad
def result = []

for (c in [1, 2, 3, 4]) {
    if (c % 2 == 0) {
        result << c
    }
}

// good
[1, 2, 3, 4].findAll {
   it % 2 == 0
}


    

  • Use collect to apply a function to every element of a collection
    • 



// bad
def result = []

for (c in ['a', 'b', 'c']) {
    result << c.toUpperCase()
}

// better
['a', 'b', 'c'].collect { it.toUpperCase() }

// good
['a', 'b', 'c']*.toUpperCase()