How to retrieve derived classes as is from a Map?

Question

I have to retrieve Derived class objects stored in a Map given the respective class name as key. As show below trait Caluclator class PreScoreCalculator(data:Seq[Int]) extends Caluclator class BenchMarkCalculator(data:Seq[Int]) extends Caluclator val calculatorsLookUp:Map[String, Calculator] = Map[String, Calculator]( "PreScore" -> new PreScoreCalculator, "BenchMark" -> new BenchMarkCalculator ) Given key name i need to get respective object/instance from Map def getCalculatorByOperationName(operation:String) : Option[ Calculator] = { calculatorsLookUp.get(operation) } I am calling as below val calcName = "PreScore" val opt = getCalculatorByOperationName(calcName) if(opt.isInstanceOf[PreScoreCalculator] ) /// this is coming as false calculationController.calculate(opt) // this is not being executed. Expect : Execute calculationController.calculate(opt) Error : Above if condition is false hence not getting executed. So how to handle this problem? How to handle below i.e. default constructor objects ? class PreScoreCalculator(data:Seq[Int]) extends Caluclator JavaScript questions and answers, JavaScript questions pdf, JavaScript question bank, JavaScript questions and answers pdf, mcq on JavaScript pdf, JavaScript questions and solutions, JavaScript mcq Test , Interview JavaScript questions, JavaScript Questions for Interview, JavaScript MCQ (Multiple Choice Questions)

Answer 1

You have a small bug: opt is of type Option[Calculator] In Scala a nice way to handle that is pattern matching: opt match { case Some(calculator: PreScoreCalculator) => calculationController.calculate(calculator) case _ => // nothing to do } Or do it in a more declarative way: opt.filter(_.isInstanceOf[PreScoreCalculator]) .foreach(calculationController.calculate) However the use of instanceOf is a bit of an anti pattern. As a tip: Use println(opt.getClass) > then you see the class.