Question

Below class does not compile, if I declare Functions as an object instead of class I can run the method fac using Functions.fac(3) . Does it make sense in scala to attempt to run a class like this ? How can the below code be modified so that it runs without changing to object instead of class ?

class Functions {

  def fac(n : Int) = {
    var r = 1;
    for(i <- 1 to n) r = r * i;
    r
  }
     def main(args:Array[String]) = {
      Functions f = new Functions();

      print(f.fac(3));
  }

}

Answer 1

The most obvious problem in your code is that you have Functions f = .... This is Java syntax, so in Scala you need it to say val f: Functions = ...

Second, Scala makes a larger distinction between static and non-static things than Java. In Scala, something that’s static (such as a main method) is declared in an object. So you should separate the object (static) parts from the class parts.

Third, your fac function could be more simply written as (1 to n).product.

Finally, you don’t need the semi-colons.

class Functions {
  def fac(n: Int) =
    (1 to n).product
}

object Functions {
  def main(args: Array[String]) = {
    val f: Functions = new Functions()
    print(f.fac(3))
  }
}