Kotlin ClassTask_2020_06_24 (Simple Classes)

package com.hackeru.mykotlinapp
//targil 26/06/2020:
class ClassTask_2020_06_24 {
    fun main() {
        val nerd = ComputerTeacher("zeev", "mendeli")
        val pewDiePie = Gamer("Felix", "Arvid")
        val myMan = BusinessMan("steve", "jobs")
        nerd.talk()
        nerd.walk()
        nerd.eat()
        pewDiePie.playGame()
        pewDiePie.talk()
        pewDiePie.walk()
        pewDiePie.eat()
        myMan.makeBusiness()
        myMan.talk()
        myMan.walk()
        myMan.eat()
    }
}

open class Person(val firstName: String, val lastName: String) {
    fun talk() {
        println("$firstName $lastName saying: \"blah blah blah...\"")
    }

    open fun walk() {
        println("$firstName $lastName is walking")
    }

    fun eat() {
        println("$firstName $lastName is eating")
    }
}

class ComputerTeacher : Person {
    var subject: String = "Computers"

    constructor (firstName: String, lastName: String) : super(firstName, lastName) {
        this.subject = subject
    }

    fun teachComputer() {
        println("$subject class is thought by teacher: $firstName $lastName")
    }
}

class Gamer : Person {
    var subject: String = "Gamer"

    constructor (firstName: String, lastName: String) : super(firstName, lastName) {}

    fun playGame() {
        println("$firstName $lastName is a $subject playing Call of Duty III: Modern Warfare!")
    }
}

class BusinessMan : Person {
    var subject: String = "BusinessMan"

    constructor (firstName: String, lastName: String) : super(firstName, lastName) {}

    fun makeBusiness() {
        println("$firstName $lastName is a $subject making tons of $$$$$$$")
    }
    override fun walk() {
        println("$firstName $lastName dont need to walk, he has BMW!")
    }
}