You just need the size
method on a Set:
scala> Set(1).size
res0: Int = 1
scala> Set(1,2).size
res1: Int = 2
See also the documentation for Set.
Let's say your other function is called getSet
. So all you need to do is call it, then check the size of the resulting Set
, and return a value depending on that size. For example, I shall assume that if the set's size is 1, we need to return a special value (a Set containing the value 99) - but just replace this with whatever specific result you actually need to return.
def mySet = {
val myset = getSet()
if (myset.size == 1) Set(99) // return special value
else myset // return original set unchanged
}