In groovy [].sum() returns null when I expect 0

Question

In groovy [].sum() returns null when I expect 0

Answer 1

According to https://issues.apache.org/jira/browse/GROOVY-2411 this is expected behaviour as sum() works for an array of Strings as well. The solution is to use [].sum(0) which will return 0.

Answer 2

If you really want zero with an empty list, you can always use:

List foo = []
def bar = foo.sum() ?: 0
assert bar == 0

The elvis operator will only evaluate the right hand side if the left hand side is null.