FAQ: Inheritance and Polymorphism - Review of Inheritance and Polymorphism

This community-built FAQ covers the “Review of Inheritance and Polymorphism” exercise from the lesson “Inheritance and Polymorphism”.

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FAQs on the exercise Review of Inheritance and Polymorphism

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Difference between Polymorphism and Method Override

In the Cheatsheet examples, on Polymorphism, we have the ‘cat’ class definition:

class Cat extends Animal {
public void greeting() {
System.out.println(“The cat meows.”);
}
}

and in the Method Override example, we have the class definition:

class Dog extends Animal {
// Dog’s eating method overrides Animal’s eating method
@Override
public void eating() {
System.out.println(“The dog is eating.”);
}
}

I’ve not understood the difference in the inheritance between these two. The example functionality appears the same.

Can you explain the difference between using ‘@Override’ and not…?

Thanks!

@Override isn’t necessary but it’s highly recommended. It improves code readability, helps you catch silly spelling mistakes, and stops you accidentally defining a brand new method without you realizing. It saves a lot of time while debugging as your compiler will check for you to make sure you’re actually overriding something, and will let you know if you aren’t. :slight_smile:

Do I understand correctly that there’s no way for me to know the length of spaghetti without creating a Spaghetti object in the main method? Like this

public static void main(String[] args) {
    Noodle spaghetti = new Spaghetti();
    System.out.println(spaghetti.lengthInCentimeters);

P.S.: By the way, check out my eatNoodle method! Isn’t it great? In addition to the following, it requires adding one more parameter to each of the subclasses

import java.util.Random;

class Noodle {
  
[...]

  protected boolean isPlural;
  protected double amountLeft = 20;
  protected boolean isEaten = false;
  protected static boolean isAmbulanceComing = false;
  
  Noodle(double lenInCent, double wthInCent, String shp, String ingr, boolean pl) {

[...]

  this.isPlural = pl;
  }

[...]

  public void eatNoodle(double amnt){
    double amountEaten = amnt;
    String name = this.getClass().getSimpleName();
    double timeToEat = lengthInCentimeters * widthInCentimeters * amountEaten;
    Random random = new Random();
    int randomInt = random.nextInt(10)+1;
    if(!isAmbulanceComing){
      if(amountEaten <= amountLeft){
      amountLeft = amountLeft - amountEaten;  
        if(amountEaten < 10){
          if(name == "Spaghetti"){
          System.out.print("\n" + name + " have been eaten in " + timeToEat + " minutes!");
          } else {
          System.out.print("\n" + name + " has been eaten in " + timeToEat + " minutes!");
          }
          System.out.print(" You can feel those nice and " + shape + " " + ingredients + " noodles giving off their sweet nutrients in your gastrointestinal tract. ");
          if(randomInt <= 3){
          System.out.println("Magnificent!");
          } else if (randomInt >= 7){
          System.out.println("Marvelous!");
          } else {
          System.out.println("Delectable!");
          }
          if(amountEaten > 1){
          System.out.println("\nBy the way, did you really eat " + amountEaten + " kilogram of " + name.toLowerCase() + "?");
          }
        } else {
        System.out.println("\nDid you just eat " + amountEaten + " kilogram of " + name.toLowerCase() + "?! I'm calling the ambulance!");
        isAmbulanceComing = true;
        }
      } else {
      System.out.println("\nUnfortunately, there's only " + amountLeft + " kg of " + name.toLowerCase() + " left. You can't eat " + amountEaten + " kg of it!");
      }
      if (amountLeft == 0.0){
      isEaten = true;
      }
    } else {
  System.out.println("\nYou're not gonna consume one single noodle no more!");
    }
  }

P.P.S.: My eatNoodle method works perfectly, but it seems I encountered a bug. Do you have any idea why it happens?