#8.4 Kotin Beginner Tutorial INHERITANCE Demo Part 4 Video Lecture - Kotlin

high resistance in the hearts and
welcome to the next video of the concept
of inheritance in this video we will
check out the demo for the concept of
inheritance in Kotlin so here inside the
IntelliJ IDE I have simply defined some
code just to save time so here I have
class dog inside the class dog I have
some properties of color and breed both
are of the type of string and I have
some function of bark and eat now down
the side I have another class of cat
that contains the properties of color
and age and also the functions of MU and
eat right now if you compare both the
class here we have variable color and
function eat and here as well I have
variable color and function eat so don't
you think the codes are redundant and
they need to be optimized the answer is
yes we can optimize the code here as
well so how to do it so here comes the
concept of inheritance into picture so
both cat and dog are actually animal
like we all humans are so here I will
simply create a class of let's say
animal and now inside this I will simply
define this variable color simply cut it
and paste it inside the class of animal
and then simply cut the function of eat
from here and then paste it inside the
class of animal and now simply remove
the white space here as well
and now inside the cat let us remove the
wear color and also remove this function
eat so here we will apply the concept of
inheritance in case of dog so to apply
inheritance in case of Cortland we will
use colon space animal right now here it
will show some error let me tell you
what is it similarly in case of cat as
well I will simply use colon space
animal now in the previous video we
talked about the property of a class
such as by default the classes
our public and final so by default you
cannot inherit the properties of a class
and to apply the concept of inheritance
you have to use the keyword of open so
here by default whatever class and
functions or variables that you define
in case of Cortland are actually public
and final in nature right so here it
shows that these two are actually
redundant because by default every class
is public and every class is final
now same applies to this variable as
well which is again public in nature by
default and also final in nature by
default so you need not to specify it
explicitly because this is the default
behavior in Kotlin so let us remove it
here now same thing applies to this
class animal as well where this class is
actually public and final so that is
where the compiler will simply throw an
error that this animal is actually
public and final and cannot be inherited
so by default when you want to inherit
some properties in case of Cortland you
have to make a class open by using the
open keyword now as soon as you declare
open so this class is now no longer
final in nature and this class can be
inherited in case of dog and also in
case of cat and now let's see what is
the error again so here it says that the
animal has to be type of constructor so
here I will simply use a constructor
sign and now the error has gone and
similarly in case of cat let us use a
constructor sign and now again the error
has gone so let us now move inside the
main method and here I will simply
declare where dog equal to let's say dog
so this will simply create the object of
the dog now I can simply use dog dot
breed equal to let us say labra and
similarly dog dot let's say color equal
to let us say black and now similarly I
can simply call the methods such as dog
dot bark
and also dog dot eat right now notice
here that this dog dot color is actually
the part of class animals that we have
inherited inside the class of dog and
similarly when we call this dog dot eat
method then it is simply calling the
method present inside the animal class
now same thing will apply for the cat
object so let us define the cat object
so here as well we are calling cat dot
color that simply points to this color
variable present inside the animal class
and similarly cat dot eat simply
triggers this method inside the animal
class and now at the end suppose if I
create where space animal equal to
animal let's see what happens and then
if I use animal dot operator so here you
will find only two options color equal
to let's say white by default animals
are white let's say let us call it white
animal dot let us say eat and now apart
from color and eat you don't have any
properties inside the animal class
because this animal is actually the
top-level class that does not inherit
from any other class right so in this
video we learnt the basics of how do we
apply inheritance in case of Kotlin and
now if you run the code then these
methods will be called and you will get
some output in the output console such
as eat bark and Moo something like that
so in this video we learn the basics of
how do we apply the inheritance in case
of Cortland and now there are lot more
things that need to be discussed from
the next video onwards so let's check it
out in the next video