Hello and welcome to this session on how to
create classes and objects in object-oriented programming Today we are going to see how
do we convert information into tables? Then how do we create a class and variable
using this table? How do we create objects? And we will look at a very simple example
of an object-oriented program in Java It is taken in the last session We have already
seen how can we look into a scenario and find out the nouns or the entities, and then we
can design or define our classes We have also seen how does an account holder looks like
in real world? So for example, Tom is an account holder So
is Henry and Sara Any account holder will have attributes or variables like first name,
last name, age, account balance, and eligible for credit card And they can be some functions
like testing their eligibility for credit card, deposit money, withdraw money, and so
on In object code In programming, the same information is imitated in the class So an
account holder class will have the same variables like first name, last name, Ah, account balance,
eligibility for credit card, and we'll have the similar functions So if you take example
of a Java class, the account holder class in Java will have all these variables and
then all these functions We are going to look at how exactly we do it Practically Step 1
will be we are going to represent the account holder details in the form of a very simple
table Let us create an account holder table and the column names will be the variables
So we have first name, last name, each account balance eligible for credit card So if you
want to put in the values for Tom, we will have first name is Tom, last name is Smith,
his age and his account balance. Similarly, for Henry, we can put down his
values And so for Sara So now we have details of all these account holders We do not know
the eligibility for credit card So let us put in a very simple condition that if age
is greater than 25 and account balance is greater than or equal to 20,000, then the
person is eligible for credit card Now this is a processing So this will go into a function
and then the results will come back to the table Let us see, how do we do it in Java? So step 2 is we will create a Java class with
the name as the table name and the variables as the column names So here the table name
is account holder So we will create a class by the name account holder, and we will add
the variables as the column names Let us go to our eclipse and let me create a very simple
package here, and I will call it classes and objects And under this package I'm going to
create a new class and I will name it as account holder So we have got our account holder class
and now we have to keep the variables So we had first name, last name, age, account balance
eligible For credit card No, these are the variables we will give the data types The
first name should be a data type, a string Last name should be string, age should be
an integer Account balance can be a float number, and then this can be a pull in value
So you can see we have simply taken the table and its columns and created a class out of
it in edit our variables Now let us go to the next step Step number 3 is we have to
create another class where we will create objects for the account holder class So let
us go and create another class I will right click on my package, go to new Select class
And here I can give the name as account holder objects And I will say finish here I want
to have some function So I will have the main function You can give the name as mean press
control space on your keyboard, press enter, and you will get the declaration of this main
function And now it is saying that we have to create objects for account holder class
How do we do this? So we have to give the name of the class,
account holder and the object name For example, I want to create an object for Tom So I will
say Tom equal to new account holder name of the class with the brackets So this particular
statement create objects in Java Now we will go deeper into how this exactly works in the
coming session But for now you can assume that this statement creates an object for
Tom And Similarly we can create object for Henry I can give any name, so I will give
Henry here and Similarly for Sarah So these statements have created 3 objects Okay, so
we have created the object and now we will be giving the details of these objects or
the account holder to the particular object So for Tom I will say firstname="Tom", Tom.lastname
="Smith" You have to give the semicolon the end to do age equals 21. Tom.account balance equals 10,000 And now
we have this eligible for credit card So for this we should be having some function that
will test this particular condition So let us go back to our account holder class and
create a simple function to do this processing I will say public avoid test eligibility for
credit card And here I will put the condition that if each is created than 25 and account
balance is created in or equal to 20,000 then the person is eligible for credit card So
the same thing I'm going to give here age is greater than 20 Sorry, 25 And account balance
is created in or equal to 20,000 Then this particular variable should be true Okay, otherwise
it should be false So now we have this function which will test the eligibility in the account
holder object class I can now call this function for Tom by giving the object name and the
function name So what this particular statement will do This will call the function test eligibility
for credit card by passing the values for Tom So it will pass 21 and 10,000, and it
will call this function Of course, the result should be false, so we can print that as well
I can do this out You can also use the shortcut You can type SYSO and then press control space
And then I will say Tom.eligible for credit card, and this should print as false I can
also put some statement before it is Tom eligible for credit card, and they should print as
false Let us now test it You can run this program I'm doing a right click run as Java
application, and you can see the result is Tom eligible for credit card It is showing
me false So we can do the same thing for Henry I will just copy this Paste this again and
do this for Henry So I'm replacing Tom with Henry So this is the object for Henry Let
me just replace all the tom's with Henry here as well And now I have to keep the details
for Henry So first name is Henry Last name is Hill, age is 31 Account balance for Henry
is 20,000 And now it will test this particular function with the details of Henry Sort will
test this function with age 31 and account balances 20,000 And then it will print the
result of whether Henry is eligible or not In this case, they should print as true Let
us test it Let us run it again And Yes, you can see the results for Tom eligibility is
false and for henry eligibility is true Okay So this is how we can convert our information
to tables and then two classes and objects in Java So we have already ran this program
and validated it And now we know the eligibility for credit card in case of Tom is no In case
of Henry is Yes And of course, if we create an object for Sara, it will come as Yes Again
So this is how you can think of object oriented programming Java and create objects and classes
I hope all this information is very clear to you I will meet you in the next session,
Thanks for watching.
