How can I compare two lists in Groovy

Question

How can I compare the items in two lists and create a new list with the difference in Groovy?

Answer 1

Collections intersect might help you with that even if it is a little tricky to reverse it. Maybe something like this:

def collection1 = ["test", "a"]
def collection2 = ["test", "b"]
def commons = collection1.intersect(collection2)
def difference = collection1.plus(collection2)
difference.removeAll(commons)
assert ["a", "b"] == difference

Answer 2

I'd just use the arithmetic operators, I think it's much more obvious what's going on:

def a = ["foo", "bar", "baz", "baz"]
def b = ["foo", "qux"]

assert ["bar", "baz", "baz", "qux"] == ((a - b) + (b - a))