Groovy 2.5.0 adds several methods to make working with Java 8 Streams more Groovy. First of all the methods toList and toSet are added to the Stream class. These methods will convert the stream to a List and Set using the Stream.collect method with Collectors.toList and Collectors.toSet as argument. Furthermore we can convert any array object to a Stream using the stream method that is added to all array objects.
In the following example we use the support of converting an array to a Stream and then getting a List and Set from the stream:
def sample = ['Groovy', 'Gradle', 'Grails', 'Spock'] as String[]
def result = sample.stream() // Use stream() on array objects
.filter { s -> s.startsWith('Gr') }
.map { s -> s.toUpperCase() }
.toList() // toList() added to Stream by Groovy
assert result == ['GROOVY', 'GRADLE', 'GRAILS']
def numbers = [1, 2, 3, 1, 4, 2, 5, 6] as int[]
def even = numbers.stream() // Use stream() on array objects
.filter { n -> n % 2 == 0 }
.toSet() // toSet() added to Stream
assert even == [2, 4, 6] as Set
Written with Groovy 2.5.0.
