Java Tutorial 11: Java Inheritance and Polymorphism Video Lecture | Selenium Test Automation:Tutorial for Beginners (English) - Software Testing

selenium class 15 Java inheritance and
polymorphism say Java
oops oops transferred object-oriented
programming system object-oriented
programming system say for fundamentals
of object-oriented concepts for
fundamentals of hoops say for
fundamentals of oops
one is inheritance inheritance next
polymorphism polymorphism next
abstraction abstraction next last one
encapsulation encapsulation these are
the four fundamentals of oops say first
inheritance inheritance okay Sanji de
have an idea what is inheritance
inheritance different we can use
different class different class together
now we together less clarity are no
Clara
Sinhala three have any idea what is
inheritance it is global concepts not
only in Java in all object-oriented
programming languages you can find this
inheritance
what is inheritance yes
inheritance is a mechanism that if we
create a class inside of any class if we
engage another class we can use those
method from the another class from the
another class okay okay say it is a
footnote footnote inheritance it is a
process of inheriting inheriting means
reusing it is a process of inheriting
the class members class members
variables and methods variables and
methods are called as class members it
is a process of inheriting the class
members from one class to another this
is called inheritance say it is a
process of inheriting
heretic inheriting means reusing reusing
the class members class members what are
the class members variables and methods
variables and methods methods means here
user-defined methods if it is built-in
method you can access from anywhere
variables and methods from one class to
another from one class to another okay
next non-static class member c class
members two types static class members
non-static class members non-static
class members only can be inherited what
is the difference between static class
members and non-static class members we
access static class members using
madhumathi what is the primary
difference between static and non-static
class members how we access non-static
class members
sar no you continuous Angie de put nota
remaining people honestly non aesthetics
class member we can access by creating
objects yes
by creating object using instance of the
class we can access how we access a
static class members member we can
accept directly through the class using
class name using class name see here on
condition non-static a lot of you put
note non-static class members non-static
class member solely can be inherited
inherited say next the class where the
class members are getting inherited is
called as super class or parent class or
base class say the class where the class
members where the class members or
getting inherited or getting inherited
is called as super class super class or
parent class or base base class ok next
the class to which the class members are
getting inherited is called as subclass
our child class or you can say dare I
would class see the class to which the
class members the class members are
getting inherited or getting inherited
is called as is called just a minute is
called as subclass or child class or
derived class okay next the inheritance
between super class and subclass is
achieved using he extends keyword
extends say the inheritance inheritance
between superclass so just a minute so
per class and subclass is achieved
achieved using extents don't use double
quotes in Java programs here only
understanding per point of am writing
double course extents small letters
extends keyword see this is a brief
introduction about inheritance next I
will show what are the static members
and non static members before that
already we discussed them how to create
static class members Sunol how to create
static class members
using static non access modifier using
static this is non access modifier non
access modifier okay next how do we
access static class members sridevi how
to access static class members already
sandy de told how to access static class
numbers using class name in class name
dot method okay using class name using
class name next how to access man static
class members gunas Natarajan how to
access non-static
let me just now sangeeta told Sanji de
answered how to access non-static class
members by creating objects creating of
the token using object our instance of
the class location using object our
instance instance of the class instance
of the class how we can access
non-static class members okay I will
show an example then we will discuss
inheritance first without inheritance
just example for creating and accessing
static and non-static class members see
example creating and accessing static
and non-static class members class
members launch Eclipse IDE just a minute
say created on class here first create
static variables are declared static
variables create or declare static
variables variables and the methods are
called as class members see using static
keyword static int a equal to 10 B equal
to 20 like this okay before main method
these are class level variables they
load only once you can use your number
of times if it is other variables
non-static variables they load every
time when object is created suppose in
the first class main class you create
object non-static class members load
suppose in second class subclass if you
create another object they load once
again they load again C memory point of
view static class members are better
class level c next create static method
create a guide me pretty create just a
minute before that create or declare
non-static nonce that
variables first we will complete
variables just without static keyword
into c equal to p be equal to 40 like
this next create static method create
static method with returning value we
will discuss all flavors with a create
static static method all of you put note
except pretty with retina value or guide
me pretty how to create static method
with returning value public public
static static in a in the returning
return type int suppose add method name
open curly brace close curly braces next
write method body suppose i ain't result
reason in the result equal to for
example
it must be next return result semicolon
say this is static method with a
returning value next madhumathi create
static method without returning any
value same create a static method you
know the syntax create a static method
create the same static method created
that without without returning any value
remain basmati public public static wide
wide means written type nothing suppose
or multiplay multiply this is method
name open curly braces without returning
any value suppose cyst just a performing
operation no passing value
into be next neela three create a
non-static method with the returning
value just a minute
create a non-static nonce that create
just a minute create a non-static method
just a minute
create a static method just just a
minute the static method next to create
a crit and non-static method create
non-static method yes sir with returning
value public public return I suppose
paint in some horse division okay you
can use same you add to another method
and another name and result on account
just a minute interests equal to C plus
B so that is true in one should be good
oh yes two times
return return return keyword return res
this this is with the returning value
next without returning value suppose
create non-static method without
returning value suppose multiply to it
is a multiplied to suppose just nor
return yes sir
we have to with public void just a
minute
public wide void no return type see in
this in this program we created non stat
static variables and static methods next
non static variables and non static
methods Sunil are you following is a
class members what are the class members
variables and
you are not responding properly civic
what are the class members variables and
methods methods we have two types of
class members what are they static not
yes static non static and how do I
access also we discuss today first
Sangeeta
I want to access static class members I
want to access static class members how
to access that one just a minute
access static class members how to
access that class name class name what
is the class name just a minute
inheritance class name dot dot okay
Chanel okay okay suppose a class name X
static class members
it is not how tell you how to print this
one no sir you exit the variable you
need pre-existing the methods yes we can
access variables also see observe we can
access variables also next method static
method add method is there that returns
a value 'no returns a value so take
variable int X equal to inheritance dot
yard just a minute
dot yard if you want to display you can
display next one more method is there
nah that is without returning value
without returning value say he
inheritance dot multiply multiply see
sandy de we can access variables also
variables also numbers naturally he
access non-static non-static class
members
access non-static class members first we
have to create instance object suppose
inheritance obj equal to new inheritance
inheritance his class name you can use
XYZ doll so next access obj just a
minute you can access variables also obj
dot C next returning value na into y
equal to obj dot he hard to if you want
to display you can display Y next
without returning value obj dot
multiplied to a Java C we are accessing
static and non-static class members
before main method creating after main
method accessing run even is showing
blank total harmony outputs so the
variable X Y into the system output in
the oven inside just a minute this is
line 34 air
good god that's why it is showing blank
blank line y X okay observe first output
ei 10 next second output 10 + 20 30 next
third output multiplied 10 into 20 200
these three outputs belongs to a static
class members next non-static C 30 next
the add to the P plus 40 what are the C
and D values 30 40 okay 70 next last
output and next static just terminated
70 next last output 30 into 42 alejandra
run the program C 10 3200 tepee 7410
tepee 230 70 1200 Okinawa Duma 'they are
following creating and accessing static
and non-static class members okay next
one condition we discussed regarding
inheritance non-static class members
only can be inherited okay before that
we will discuss one more point regarding
inheritance say we have three types of
inheritance three pipe
three types of inheritance but Java
supports two types of inheritance only
see first one single inheritance single
inheritance example public okay forget
about the syntax don't concentrate on
syntax what is single inheritance
suppose Class B Class B extends forget
about the syntax I am NOT writing
complete syntax just the inheritance pot
Class B extends Class A Class B extends
classy a observes nitrogen yes sir which
one is so which one a superclass Class B
are classy a Class A Class C a
superclass say we can access all
non-static class members from classy a
to Class B this is single inheritance
next multi-level inheritance multi-level
multi-level inheritance example suppose
Class B extends Class E a this is
level next classy extends Class B Class
B extends classy a next Class C extends
class be here observed classy a is
parent class our super class class bees
child class or subclass next class C's
sub child class our sub sub class
see for example Class C for Class C
Class B is parent and Class A is
grandparent Class C can access Class B
non-static members non-static class
members as well as grandparents classy
non-static class members also getting
this point Sangeetha any confusion no
sir okay Class B can access class a
class members Class C can access Class B
and Class C a class members this is
multi-level not only two levels you can
write Class B extends Class C just a
minute Class B extends Class C next
class E extends Class D like that next
Java doesn't support multiple
inheritance
another type multiple inheritance say
Java doesn't support
here observe the problem what is
multiple inheritance suppose Class B
extends Class A Class B extends class a
next class B same class B extends class
be observed nella dream
suppose if Class B is failed for Class A
and Class D confliction ax C priorities
problem suppose same method available in
Class A and Class D which one is first
both our parents so this is not possible
in Java
first of all Java doesn't support
multiple inheritance bear and
grandparent grand grandparent like that
but two different parents three
different parents that is multiple
inheritance Java doesn't support
multiple inheritance observe Sangeeta
hitting this this point multiple
inheritance
why why Java doesn't support multiple
inheritance different parent parents
having two parents having same methods
then priority problem which one is first
so the or doesn't support multiple
inheritance only multi-level inheritance
single inheritance okay we'll discuss a
examples just in multi-level can we do
like a class he extends carafe you just
about Madhu asking I tell my mother in
multi-level can we do necklace a extends
classy
in multi-level multi-level class yeah he
extended a Class C extends Class A Class
E not required already Class B extends
class Sienna that is not required first
of all why say class B extends Class A
if you extends Class B for Class C Class
A also available then why why we need to
extend again okay actually that is not
correct syntax not required see why a
Class B we are accessing class ea also
then why we need to extend again just a
minute I will show the example then you
can get more clarity observe
suppose create new class class ei plus e
only non-static class members non-static
create non-static class members suppose
variables in TA equal to 10 into B equal
to 20 next method method suppose method
without returning any value public wide
public void add open curly braces next
you can write method with returning
value also
Moishe say suppose a plus B next access
see these are man static class members
first we need to create object suppose
class name class a obj equal to new
class a open and close curly braces
semicolon okay next access non-static
class members say
obj dot EA next Toby J ei dot he added C
this is 31st output 10 run the program
Satan tactic okay next create one more
class new class Class B Class B
Class B suppose method same name 100-200
her create object class b DJ be equal to
new new class b new class B semicolon
and just a minute
Class B hobby JB just comment this one
just comment wide is showing error Sanji
de yeah we need to extends C Class B
zero nil Adri suppose without
inheritance if you want to access class
non-static last members from Class A
then how to access you need to create an
object in class Sienna yes sir
ah see here we are creating object in
Class B only Class B object to be new
Class B if you want to access parent
class first you need to inherit yes
extents class yay
now you can access class II a non-static
class members here we are accessing one
variable and one method run the program
eight entity accessing observe Sridevi
for example same names variable name
same and method name also same same
names available in sub class as well as
parent class then how it executes what
is the out
see earlier no first priority first
priority goes to local class next
priority parent class suppose in the
local class means same class variable
here not available and a yard method not
available then it goes to parent class
suppose in the same class variable a and
method a are available then first
priority goes to local class C hundred
this is 300 observe Sanji de yes 100 300
no confliction parent and child classes
say having same names class members
rarely names same method name same then
how it executes first priority
overloading no that concept is different
that I will show next polymorphism
chocolate okay I will show I will show
you would you don't focus on overloading
overriding concept now just to remember
the same names available okay we are
asking good question but you don't focus
on that the overloading overriding this
time only focus on first first priority
local class next priority our nearest
apparent nearest parent suppose
grandparent also their first priority
local next priority parent last priority
grandparent okay say next create one
more class one more class
classy classy classy just a minute
observe first this is example for single
inheritance example for single single
inheritance Singh and the stamen single
inheritance class one his class one next
class to class two
next example for multi-level multi-level
inheritance he inheritance here three
classes first two classes take as it is
next class three three or more minimum
three class three just a minute
Class C suppose in Class C also same
names class member names said suppose EI
1 B 2 a 1 B 2 create object Class C
Class C objc equal to new new class II
open an open and close parenthesis just
terminated next access obj C dot just a
display that one objc dot a next objc
dot add observe nell agree how if i run
this program then what are the outputs
say in this class variable he available
and the add method available next to
parent where every a available and the
add method available and grandparent in
grandparent also wearable EA is there
and a add method also there what are the
outputs outputs one just a minute
extensive absence extends Class B now
what are the outputs first output first
priority local class home class one
wants a second output three one and
three run the program say one and three
observe a domotic suppose in this local
class means home class no variable Y a
know he had method but in parent class
variable Y a and a yard method of a add
method available and in grandparent also
variable Y EA
and add methods available then tell me
the outputs first priority home class in
the home class no such class members no
such class members then the parent class
available next to tell me the outputs
hundred three hundred run the program
one hundred three hundred next suppose
the parent also no such class members
then first priority home class second
next priority nearest apparent in the
parent also know a variable and the add
method national grandparent a variable
and add method available and what are
the outputs tenant acting run the
program tenant opee observe
Preeti getting that priority process
first authority to the whom whole class
next to priority parent class
grandparent can you go to the eclipse
for class three yes yes the line number
three when we are saying the public
three bleakness IXY extinct so we can
use class a and sudras right-click ha CA
why already somebody asked a madhumathi
Oscar I answered that one why class a
first of all not required why if you
extend
Class B then you can access Class B
class members as well as classy a class
members now if you use classy a that is
confliction ma just Emma if we just a
minute location you'll be see run this
first priority local only okay first
priority local suppose here no no such
class members just a minute no such
class members next run
the showing class the string class ei
then tell me pretty we are extend Class
C Class C extends Class A Class B
extends class hehe have no conflicts on
why a Class A is parent for two
subclasses two different subclasses
Class A can be accessible for Class B as
well as Class C then what is the problem
yes no problem say one parent can be
having multiple change suppose Class B
extends Class A Class C extends classy a
Class B extends Class C A plus Yi
extends classy a but no multiple parents
change
okay but no multiple parents then what
is the problem I got it thank you on
line number seven now could you unblock
okay no unlike number seven it is
showing the ad of what it means now it
is not showing it was showing some kind
of an arrow down arrow it no shooing or
riding concept it is showing okay told
it
okay okay let's see next nail Adri you
create an allow one more package
suppose just a minute classy a in this
class here 2 variables and 1 method next
I remove this class C we copy this one
plus C ok just a minute you remove this
class C delete next Class B Class B
observes and Edith now only two classes
classy a Class B Class B extends classy
a okay in these two classes we have same
class members same names values
different but same names okay now if I
access if I execute this class B what
will happen first priority home class
members so hundred and thirty one
hundred and thirty okay suppose Sunita
if I want to access class a class
members also then how to access same
class members available but I want to
access class a the add method and class
here a variable value how to access we
pass the parameter no Neera three yes
how do you have to create we have to
create object using class how to create
object using classy a actually that
concept not belongs to inheritance
inheritance suppose b to class
a Class A now observe Sangeeta in this
class we have two objects now yes first
object we created using same class means
home class second object we created
using parent class it can access parent
class members directly even those same
class members available in the home
class observed outputs hundred and three
hundred next 130 run C hundred three
hundred one hundred thirty just a minute
put note his class to next class one
last one
okay next create one more package
suppose Java examples new package
suppose package name package to package
- in this package - on class class see
Plus see in just a minute in this class
be
suppose Class E Class E just obg class
he just obj or is a problem when it is
not allowing nella dream here in Class B
I created object to using class IANA sir
we need to import package import package
important now
Oh Class B only imported classy a just
to obj oh it is not allowing observable
Adri this variable ei it's not public
okay
run ten thirty by importing the package
importing that package suppose if you
want to create object in this same class
Class C Class C observe Sanji da it is
showing error Y access modifier we need
to put excess motive for not access
modifier extra we need to extend now yes
we create an object in this home class
yes we need to extend extends
inheritance required extends Class A now
you can access tenant at E C this is
about inheritance single inheritance
multi-level inheritance but Java doesn't
support multiple inheritance goodness
Natarajan are you following without
without inheritance also you can access
other class members how to access
without inheritance nella 3 continue
without inheritance you have to make the
object how to create object using that
parent class parent superclass I suppose
class 1 extends class to class 2 extends
suppose multiple layers observer sandy
de Class A Class B
Class C Class B suppose without without
inheritance now I am in Class D without
inheritance
I want to access Class C class members
Class B Class members Class A Class
members yes sir then how to access we
need to create four objects not one our
home class next nearest parent
grandparent grand grandparent if we
inherit then only single object now yes
single object but one small drawback
also there if it is single object what
will happen priority process is there
usually we use unique names for
variables and methods if you don't use
unique names then of rarities say
without inheritance with inheritance we
can reuse class members but if we use
inheritance and then using single object
you can access class members for
multiple classes from multiple classes
hitting this point 3d easy safe
polymorphism
all that this is given the last sentence
what he said sir like no inheritance
without inheritance we can act we can
reuse class members okay got it without
inheritance we use the object of that
class we have to create object in parent
class okay pension polymorphism can you
tell me madhumathi what is polymorphism
have any idea polymorphism idea pardon
it in different ways taking different
ways okay can you tell me Artie Artie
yes sir
what is polymorphism
polymorphism means like many forms in
many forms okay good existence of object
behavior in many forms see the existence
of object object behavior behavior in
many forms forms means ways say
existence of object behavior in many
forms say this polymorphism were derived
from two Greek words poly and Marx poly
means many marks means ways
means many ways polymorphism means many
ways existence of object behavior in
many forms okay say there are two types
of polymorphism there are two types two
types of polymorphism polymorphism one
is compile-time polymorphism our method
overloading c compile time compile time
polymorphism or method overloading
method overloading next runtime runtime
polymorphism our newly Audrey in the
introduction chapter I introduced the
term runtime polymorphism are already
method overriding method overriding okay
say first compile time polymorphism our
method overloading see in this in the
previous chapter inheritance chapter
Sanji described method overloading
method overriding okay this concept is
related to inheritance also that we are
discussing separately related to
inheritance also what is compile time
our compile time polymorphism our method
overloading
if two are more methods having same name
in the same class but they different
they different following ways
observe Sangeeta who overloading
overriding earlier war riding MA in
inheritance inheritance two are more
methods with same name available in
super class and subclass isn't it yes
that concept is overriding earlier we
faced that problem in inheritance but
what is that one method overriding what
is overriding if two are known methods
with same name available in superclass
and the subclass that is method
overriding that that I will explain in
the second example first method
overloading see any inheritance chapter
we didn't discuss method overloading
but indirectly we discussed the method
of overriding okay now yes what is
method overloading or compile-time
polymorphism if two two are more if two
or more methods all of you put note with
same name it's same name if two are more
that's the same name in the same class
in the same class and okay if two are
more methods with same name in the same
class same parameter no no same class
but they different but they differ
different following with following ways
what are the following ways
observed one is number of arguments
number of arguments or you can say
parameters next type of arguments type
of number of arguments same but type
different type of arguments these are
the scenarios say I will show example
example observe suppose create a class
class 1 class 1 class 1 create methods
suppose public wide ok without returning
value with returning value also you can
write public wide yard parameters int a
int B open curly braces flows in PA into
B next display a plus B this is one
method addition adding two numbers you
can pass parameters values user can pass
next same name he had the same name
comma intercede
observe observe see daily method names
same now same class same method names ad
ad but what is the difference different
parameters different parameters not
different parameters number of
parameters type type same but number of
parameters suppose one more method yard
only in type different double observe
pretty first method third method first
method third method a number of
parameter a method name same number of
parameters same money
what is the difference sheet entities
type of arguments different next in
between first and second methods method
name same next type of arguments also
same but number of arguments different
okay now access created create a create
and create an object class one obj equal
to new class one
okay observe observe sandy de obj dot
yada
she heretic here showing Trina three
different methods na three methods
different arguments name same na based
on values it it it access those method
methods the object access methods object
the access methods based on parameter
values suppose observe here we can
select three suppose I am selecting to
only Stu only but if I pass three values
then it access this method only this
method middle method only suppose
observed 10 comma 20 comma 30 from comma
20 comma 30
it adds three integers run sixty
observed suppose if I use two integers
then it acts as first method run 30
suppose one point two three comma two
point three four then it acts as last
method run observe observers not bernad
it is adding W it based on the
parameters you access observe you can
object
dot add suppose 10 comma 20 next 1 comma
5 comma mine run say based on the
parameter values object access methods
this concept is propre theory following
this concept is this concept is called
method overloading if two or more
methods with the same name in the same
class next runtime polymorphism our
method were writing C runtime
polymorphism our method overriding if to
our earlier we faced this one in
inheritance if two or more methods with
same name available in the super class
and subclass if two or more two or more
methods available in the superclass
super class and subclass
subclass actually yeah there we did that
one say once again suppose class one
class one in just a minute in the class
1c public avoid my method public void my
method for example selenium for test
automation selenium for test automation
selenium for test automation create
object suppose class one obj 1 equal to
new class 1 semicolon C obj dot over you
wanna obj one dot my method run selenium
for test automation create one more
class class
to class to class to suppose same method
there is that class one okay
plus two method name say my method U of
T formerly qtp for test automation for
test automation okay extends class one
class one create object class - whoa big
a2 equal to new class - new class - next
access obj to dot my method observed or
not what is the output say same method
available in this subclass and they are
and in parent class also but it's
obviously then what is the output the
output will be U of T /qt power ought to
be talking first priority home class
next a prior suppose if method not
available then it acts as parent class
Russia
selenium for test automation is if you
want to access both one by one you need
to create a object in parent class but
that is not comes under inheritance
this is method over riding method
overriding sanji that you do follow this
one method overloading and method
overriding tell me what is method for
loading overloading same name same class
different different parameter different
overwriting means types are a type of
arguments are number of arguments next
method overriding overriding same name
same parameter okay same name same
parameters okay this is about
polymorphism
tomorrow we will discuss abstraction and
encapsulation and I need to introduce
interfaces also how to create interfaces
say as extension of abstraction topic I
will explain how to create and use
interfaces any queries madhumathi
madhumathi
any queries welcome CVV any queries
regarding these two topics one is
inheritance another is polymorphism java
whoops
object-oriented programming system soon
L soon L know sir I'm good thank you
okay welcome good not not Rajan I am
good sir thank you sir okay welcome C we
will meet tomorrow same time thank you