Inheritance in Scala: Building on Strong Foundations | CodeSignal Learn

Inheritance in Scala: Building on Strong Foundations | CodeSignal Learn

Now that we've explored the theory behind inheritance, let's see how it comes to life in Scala!

// Define the base class Person with name and age attributes
class Person(val name: String, val age: Int):
  
  // Method to display name and age
  def display(): Unit =
    println(s"Name: $name, Age: $age")

  // Method to display a greeting message
  def greet(): Unit =
    println("Hello, there!")

// Define the derived class Student, inheriting from Person
class Student(name: String, age: Int, val major: String) extends Person(name, age):
  
  // Override the display method to include the major of the student
  override def display(): Unit =
    greet()
    super.display()
    println(s"Major: $major")

@main def main(): Unit =
  // Create a Student object and display its details
  val student = Student("Bob", 25, "Computer Science")
  student.display()

In this snippet, the Student class inherits from the Person class, reusing the name and age properties as well as methods like display and greet. The Student class introduces an additional attribute, major, and overrides the display method to include the student's major in the output. Let's briefly analyze the syntax and keywords employed:

Inheritance Syntax: Use the extends keyword to denote that one class inherits from another.
Overriding Methods: Subclasses can override superclass methods to provide specialized behavior. Use the override keyword to make this explicit.
Accessing Superclass Methods: The super keyword allows you to call methods from the superclass, maintaining base functionality while extending it.

Scala

// Define the base class Person with name and age attributes
class Person(val name: String, val age: Int):
  
  // Method to display name and age
  def display(): Unit =
    println(s"Name: $name, Age: $age")

  // Method to display a greeting message
  def greet(): Unit =
    println("Hello, there!")

// Define the derived class Student, inheriting from Person
class Student(name: String, age: Int, val major: String) extends Person(name, age):
  
  // Override the display method to include the major of the student
  override def display(): Unit =
    greet()
    super.display()
    println(s"Major: $major")

@main def main(): Unit =
  // Create a Student object and display its details
  val student = Student("Bob", 25, "Computer Science")
  student.display()