Programming Groovy 2

4.3 Ways to Use Closures

We covered how to create a closure just in time, at the point of defining arguments in a method call. We can also assign them to variables and reuse them, as we’ll do here.

In the following example, ​totalSelectValues​ accepts a closure to help decide the set of values used in a computation:

def totalSelectValues(n, closure) {
  total = 0
  for(i in 1..n) {
    if (closure(i)) { total += i }
  }
  total
}
print "Total of even numbers from 1 to 10 is "
println totalSelectValues(10) { it % 2 == 0 }

def isOdd = { it % 2 != 0}
print "Total of odd numbers from 1 to 10 is "
println totalSelectValues(10, isOdd)

The method ​totalSelectValues​ iterates from 1 to ​n​. For each ...