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Video Title: Object Oriented Design
Description: Object Oriented Design
Watch more Videos at https://www.tutorialspoint.com/videotutorials/index.htm
Lecture By: Mr. Arnab Chakraborty, Tutorials Point India Private Limited
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In the previous video, we discussed about
the function oriented design.

So, in this video we are concentrating on
object oriented design, which is one of

the most popular design approaches.

So, object oriented design, in short it
will be called as OOD, works around the

entities
and their characteristics instead of the

functions which
are involved in the software system.

So, this design strategies focuses on
entities and its respective characteristics.

So, what are the characteristics are there
and what are the entities can do,

we are considering that one in our object
oriented design approach.

And the whole concept of software solution
revolves around the engaged entities.

So, now let us see the important concepts
of object oriented design.

So, what are the important concepts we are
having?

The first one is object, whatever is
getting done is by one object.

So, object, all entities involved in the
solution design are known as objects.

So, all the entities should be considered
as an object.

For example, person, banks, company and
customers are treated as objects.

And every entity has some attributes
associated to it and has some methods to

perform on those attributes.

So, in case of objects we are having some
set of attributes which will be holding

some set of data and methods are also will
be there in the objects which will decide

that what
are the permitted operations that you

can carry out
on those attributes on those values.

Next one we are going to discuss they are
classes.

So, a class is a generalized description
of an object.

So, it is a blueprint of object.

An object is an instance of a class.

We know that
an object is an instance of a class that

is instantiation
of a class will be known as an object.

Whenever we are using this term
instantiation or instance, that means,

we are allocating some memory space to
hold our data and the respective methods

which will decide
what are the permitted

operations that can
be carried out on the data.

So, class defines all the attributes which
an object can have and the respective

methods which defines the functionality of
the object.

In the solution design, attributes are
stored as variables and functionalities

are defined by the means of methods or
also known as procedures.

Next one, a very important concept that is
encapsulation.

In object oriented design, the attributes
that is the data variables and the methods

that is the operations on data are bundled
together is called the encapsulation.

This attributes, this data set and the
respective methods that is the

functionalities on those data will be
bundled together and that will be known as

the encapsulation.

Encapsulation not only bundles important
information of an object together,

but also restricts access of the data and
methods from the outside world and this is

called information hiding.

So, what will be the methods?

What are the methods that can be accessed,
that can be viewed from the outside?

What are the variables that can be viewed
or accessed from the outside?

So, this accessibility would also be
defined in this respective classes.

So, as a result of that this encapsulation
means, those data which will remain

hidden, those method which will remain
hidden, within that respective class will

also emphasize the concept of this
encapsulation.

So, encapsulation means the set of
attributes and the permitted operations in

the form of methods or procedures will be
bundled together and that is known as the

encapsulation.

So, what are the attributes, what are the
methods that can be accessed or cannot be

accessed from the outside of the class
that we can also mention explicitly.

We are having the next one that is the
inheritance.

So, object oriented design allows similar
class classes to stack up in the

hierarchical manner, where the lower or
the subclasses can import, implement and

the reuse the allowed variables and
methods from the immediate super classes

or the base classes.

This property of object oriented design is
known as inheritance.

And this makes it easier to define
specific class to create generalized

classes from the specific ones.

So, also this
inheritance actually, this inheritance

also emphasizes the
reusability of the programming code.

So, what will happen?

We will be having one super class or the
base class from where the properties and

attributes can get inherited onto the
subclasses or onto the derived classes.

So, that there is no need to define each
and every class individually.

We can inherit some
properties, some methods

from the base classes
to the derived one.

So, here in
this particular diagram, we have shown

some different types
of inheritance as possible.

So, this is the base class, say let it be
class class A.

This is our derived class or the subclass.

So, we can call it as class B.

So, it is known as simple inheritance.

So, now here you see, this is our base
class or the super class class A.

It has got inherited in the subclass that
And that is about Class B.

And Class B is the superclass of Class C.

And Class C is the subclass of Class B.

So, this is known as Multi-Level
Inheritance.

So, here you can find, this is a
Hierarchical Inheritance, because these

two classes are inheriting from the
respective only one best class.

So, that is one as Hierarchical
Inheritance.

So, in this way
we have demonstrated, we have shown

you the different
types of inheritedances are possible.

Next one is the polymorphism.

So, object-oriented design language
provide a mechanism where methods

performing similar
tasks, but vary in the

arguments and
can be assigned with the same name.

Differing methods with the same name,
but they are differing in the arguments.

Either the number of arguments are
differing or the argument data types.

This is called the polymorphism,
which allows a single inheritance

performing tasks for
different types, depending

upon how the function
is getting invoked.

So, respective portion of the code gets
executed.

In case of inheritance, it might be true
that we are having multiple functions with

the same name, but there will be no
ambiguity.

So, depending upon the parameters passed,
the depending upon the arguments or the

data type of the parameter or the number
of parameters or the respective sequences,

it will decide that which specific method
we are going to call.

So, there will be no ambiguity,
even if we are having the polymorphism.

Consider this one.

This is a case of inheritance.

You see, there is one class.

There is a best class or super class name
of the class is shape.

And here we are having this method.

The method is our draw.

We have inherited onto this line,
triangle, rectangle and circle.

This draw method, it has got inherited
here.

And they may have
some different bodies

functions
also the function may get overridden.

So, now, we are having the design process.

So, software design process can be
perceived as series of old defined steps,

though it varies according to design
approach.

So, function oriented
or object oriented it,

yet it may have the
following steps involved.

So, let us
discuss what are the specific steps with

the help of
which one software can be designed.

So, a solution design is created for from
the requirement or previous use system and

or the system sequence diagram.

So, at first we shall go for a solution
design.

From the previously built system we might
be having some idea or and or or system

sequence diagram the solution system will
be a design solution will be obtained.

Next one is the
objects are identified and grouped into the

classes on behalf of
similarity in attribute characteristics.

So, we can find that these these are the
set of attributes.

These are the set of attributes which are
common in multiple objects.

And these are the objects which are
similar in nature.

So, those objects will have a class under
which these objects will get instantiated.

So, class hierarchy and the relation among
them is defined.

And then application framework is also
defined on which this application and the

software is going to get implemented and
developed.

So, in this way we have defined what is
object oriented design.

So, in our email tutorial also we have
discussed this object oriented analysis

and object oriented design into more
details.

You can also watch that tutorial also.

Thanks for watching this video.