user3619698 user3619698 - 2 months ago 4
Scala Question

Can an object extend abstract class in scala?

I am newbie to scala . I am trying to create an Object that extends abstract class like show below

object Conversions extends UnitConversions
{
override def inchesToCentimeters(inches:Int) = inches * 2.5
override def gallonsToLiters(gallons:Int) = gallons * 3.78
override def milesToKilometers(miles:Int) = miles * 1.6
}

abstract class UnitConversions
{
def inchesToCentimeters(inches:Int)
def gallonsToLiters(gallons:Int)
def milesToKilometers(miles:Int)
}


While i try to access the object's member functions i get () this expression as output .

Conversions.milesToKilometers(20) //I get output ()


More over is the below statement valid ???

var ucv:UnitConversions = new Conversions
println(ucv.milesToKilometers(3)) // I get output () here as well


Thanks in Advance !

Answer

You need to provide a return type for the functions, otherwise they return Unit:

abstract class UnitConversions {
  def inchesToCentimeters(inches:Int): Double
  def gallonsToLiters(gallons:Int): Double
  def milesToKilometers(miles:Int): Double
}`