Checking how many elements a set contains

Question

I need to write a function that returns true if a set (this set is the output of another function) contains 1 element and otherwise it leaves the set as it is. For example: Set(1) returns a specific result and Set(2,4) returns the set as it is. How can I check how many elements a set contains?

Accepted Answer

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
}
```

Checking how many elements a set contains

Solution

Problem