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scalarecursiontypesmaxmismatch

I am trying to implement a recursive function in Scala to calculate Maximum value in a List

def max(xs: List[Int]): Int = {
  if (xs.isEmpty) throw new java.util.NoSuchElementException("List is Empty")
  else
     max1(0,xs)

  def max1(num :Int, x : List[Int]) : Int = {
    if(x.isEmpty) return num 
    else if(num>x.head) max1(num,x.tail) 
    else
      max1(x.head,x.tail)
  }
}

I am trying to Implement code to throw error when it gets an empty list as input and trying to get the maximum value of the list in a recursive way using another helper function

error: type mismatch; found : Unit required: Int

Solution

  • Put the definition of max1 before the if statement. The return value of a function is the result of the last statement in its body. The way you have it now, the last statement is def, and it's result is Unit.