Understanding Case class and Traits in Scala

Question

I have a simple trait as defined below:

trait MyTrait {

  def myStringVal: String

}

My case class which implements this trait is as below:

Answer 1

Scala case classes have a plenty of boilerplate implemented for you, and having all the constructor parameters automatically exposed as vals is one of these things.

If you try avoiding vals in a regular class, like that:

trait MyTrait {
  def myVal: String
}

class MyClass(myVal: String) extends MyTrait

Compiler will show you the error message, that MyClass has to be abstract, as it does't override myVal method, but adding val or var to the class constructor parameter will solve the issue.