Scala Programming Projects

Abstract class

An abstract class is a class that can have many abstract members. An abstract member defines only a signature for an attribute or a method, without providing any implementation. You cannot instantiate an abstract class: you must create a subclass that implements all the abstract members.

Replace the definition of Shape and Rectangle in the worksheet as follows:

abstract class Shape(val x: Int, val y: Int) {  val area: Double  def description: String}class Rectangle(x: Int, y: Int, val width: Int, val height: Int)  extends Shape(x, y) {  val area: Double = width * height  def description: String =    "Rectangle " + width + " * " + height}

Our class Shape is now abstract. We cannot instantiate a Shape class directly anymore: we have ...