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October 11, 2009

Groovy Goodness: Finding Data in Collections

Groovy adds several methods to Collection classes to find elements in the collection. The findXXX() methods take a closure and if an element matches the condition defined in the closure we get a result. We can also use the any() method to verify if at least one element applies to the closure condition, or we use the every() method to everify all elements that confirm to the closure condition. Both the any() and every() method return a boolean value.

def list = ['Daffy', 'Bugs', 'Elmer', 'Tweety', 'Silvester', 'Yosemite']
assert 'Bugs' == list.find { it == 'Bugs' }
assert ['Daffy', 'Bugs', 'Elmer'] == list.findAll { it.size() < 6 }
assert 1 == list.findIndexOf { name -> name =~ /^B.*/ }  // Start with B.
assert 3 == list.findIndexOf(3) { it[0] > 'S' }  // Use a start index.
assert [0,3,5] == list.findIndexValues { it =~ /(y|Y)/ }  // Contains y or Y.
assert [3,5] == list.findIndexValues(2) { it =~ /(y|Y)/ }
assert 2 == list.findLastIndexOf { it.size() == 5 }
assert 5 == list.findLastIndexOf(1) { it.count('e') > 1 }
assert list.any { it =~ /a/ }
assert list.every { it.size() > 3 }

def map = [name: 'Messages from mrhaki', url: 'http://mrhaki.blogspot.com', blog: true]
def found = map.find { key, value -> key == 'name' }
assert found.key == 'name' && found.value == 'Messages from mrhaki'
found = map.find { it.value =~ /mrhaki/ }
assert found.key == 'name' && found.value == 'Messages from mrhaki'
assert [name: 'Messages from mrhaki', url: 'http://mrhaki.blogspot.com'] == map.findAll { key, value -> value =~ /mrhaki/ }
assert 1 == map.findIndexOf { it.value.endsWith('com') }
assert [1,2] == map.findIndexValues { it.key =~ /l/ }  // All keys with the letter 'l'.
assert 2 == map.findLastIndexOf { it.key =~ /l/ && it.value }
assert map.any { entry -> entry.value }
assert map.every { key, value -> key.size() >= 3 }