#8.3 Kotlin Object Oriented Programming: INHERITANCE Explanation Video Lecture | Kotlin Tutorial for Beginners: Learn Kotlin in easy language - Back-End Programming

hi little stirrings of the earth once
again welcome to the next video of
object-oriented programming in case of
Kotlin now in this video we will learn
about what is inheritance is all about
but before that let us first understand
the properties of the class in case of
Cortland now by default all the classes
in Cortland are public in nature and
also they are final in nature that is by
default you cannot inherit from a
particular class to the derived class or
the subclass so for that the core
training provides a special keyword of
open keyword to inherit all the
properties of a particular class you
have to use the keyword of open and now
for those who are beginners who do not
know what is inheritance please continue
with this video and for those who know
what is inheritance quite well you may
skip this video and continue watching
the next video which is the demo video
so let us now proceed and check out what
is actually inheritance in case of
Cortland so suppose I have here class of
dog and here I have class of cat now in
case of class dog I have some properties
such as color breed and some methods
such as bark and eat now similarly here
in case of class cat I have the
properties of color and age and also
some methods of MU and Eid if you
compare both class dog and class cat you
will find there are some common
properties such as here I have color
here I have color too here I have
function Eid and here I have function
Eid so there is obviously some code
repetition in both the classes so can we
optimize both these classes yes we can
with the help of inheritance we can
simply create a class of animal from
which the class cat and class dog will
inherit all the properties so inside the
class animal what I will have is I will
declare the property of color and also a
method of it now this color and this eat
method is actually present inside the
Dhokla
and also inside the cat class so with
the help of inheritance we can simply
inherit all the properties of animal
class into da class and also PLAs cat so
in case of class dog I will simply
modify my code and inherit all the
properties from the animal class like
this class dog : animals now this is the
syntax to inherit all the properties
from the class of animal in case of
Cortland colon followed by animal and
this is the default primary constructor
that is called
right and in case of cat as well we can
again use the concept of inheritance
colon space animal right and if you
notice in case of cat and dog we have
simply removed the properties of color
and each function and now we are only
left with the age and mu and here breed
and birth just because these two
properties are actually present in case
of animal that these two classes are
getting indirectly so this concept in
case of Cortland is known as inheritance
right and now proceeding forward the
class talk and class cat is actually
known as the subclass the child class or
the derived class similarly this animal
class and this animal class is actually
known as the superclass base class or
parent class right like this and FF all
we have this animal class which is
actually known as the superclass base
class or the parent class right now this
animal class by default inherit from a
class of any now this NE is actually the
name of the class that contains few
functions so in Cortland always remember
every class you define inside your
project has a superclass of any and this
any contains few functions that I will
talk about it shortly and now proceeding
forward let us now check out the type of
inheritance supported in case of
Cortland so the type of inheritance is
same as that of Java we have the single
inheritance multi-level inheritance and
also hierarchical in here
so in case of single inheritance suppose
I have Class B that simply inherits from
Class A and in case of multi-level
inheritance
I have multi-level inheritance such as
plus C inherits from Class B inherits
from Class A like this now in case of
hierarchical inheritance I have some
structure that appears to be like this
Class B and Class C inherits from Class
A and this is the same example that we
saw in the previous slide of dog cat and
animal and now at the top in each of the
case we have class a Class A and Class A
so all these Class A actually inherit
from the any class at the end right so
always remember in case of Cortland we
have a superclass of any at the top and
now this Class B Class C and here this
Class B and Class C are actually known
as the derived class and this class a
which is present here is actually known
as the superclass always remember this
and now in case of multi-level
inheritance we have this class be
present in between the Class A and Class
C so for this class C this B is actually
acting as a superclass but for this
class a this B is actually acting as a
derived class or the child class always
remember this again
now what about Class C here we have
Class B and Class A as a superclass for
this Class C so indirectly we are
getting all the properties of Class B
and Class A inside plus C because we are
having here multi-level inheritance so
the class present at the bottom will get
all the properties of the classes
present above it such as Class B and
Class A as well and along with it class
any by default now what this class and
he stands for now this class any simply
contains some default functions such as
equals method
hashcode method two string method now
these methods simply return some value
which is boolean in nature integer and
string respectively and what are the
usage of these methods we will talk
about it shortly in our demo video but
before that let us now define our
inheritance in case of Cortland so in
case of Cortland we can define
inheritance as it is a mechanism in
which one object class acquires all the
properties from its parent class
right now what is the purpose of
inheritance so the inheritance simply
increases the code reusability which we
saw in this video and it also promotes
the method overriding functionality now
till now we have not seen what is Method
overriding in case of Kotlin so we will
check it out shortly