Abstract Class : Example...

scala> // An Abstract Class cannot be Instantiated #219

scala> // Abstract key word is Mandatory for an abstract class

scala> abstract class Subject {
     |     //These are abstract methods
     |     //  as it do not have any definition, but only
     |     //  declaration #220
     |     def name: String
     |     def mark: Int
     | }
defined class Subject

scala>

scala> //We cannot instantiate an abstract class

scala> val sub = new Subject()
<console>:24: error: class Subject is abstract; cannot be instantiated
       val sub = new Subject()
                 ^

scala>

scala> //This does not compile..as we do not give the

scala> //  abstract keyword

scala> class Subject {
     |     //These are abstract methods
     |     //  as it do not have any definition, but only
     |     //  declaration #220
     |     //abstract keyword is optional for a method
     |     def name: String
     |     def mark: Int
     | }
<console>:11: error: class Subject needs to be abstract, since:
it has 2 unimplemented members.
/** As seen from class Subject, the missing signatures are as follows.
 *  For convenience, these are usable as stub implementations.
 */
  def mark: Int = ???
  def name: String = ???

       class Subject {
             ^