Choosing the last element of a list

Question

scala> last(List(1, 1, 2, 3, 5, 8)) res0: Int = 8 

for having a result above, I wrote this code:

val yum = args(0).toInt val thrill:   def last(a: List[Int]): List[Int] = {      println(last(List(args(0).toInt).last)      } 

What is the problem with this code?

Answer 1

You can use last, which returns the last element or throws a NoSuchElementException, if the list is empty.

scala> List(1, 2, 3).last res0: Int = 3 

If you do not know if the list is empty or not, you may consider using lastOption, which returns an Option.

scala> List().lastOption res1: Option[Nothing] = None  scala> List(1, 2, 3).lastOption res2: Option[Int] = Some(3) 

Your question is about List, but using last on a infinite collection (e.g. Stream.from(0)) can be dangerous and may result in an infinite loop.

Answer 2

Another version without using last (for whatever reason you might need it).

def last(L:List[Int]) = L(L.size-1)