Java Essentials - Class and objects in java

In this video we are discussing class and objects in Java

Class is nothing but one common blueprint of objects and one object is nothing but instant

session of a class. When you define one class, no memory space is going to define or going to occupy in the computer's

memory during the runtime of the program. But whenever we define one object under the class, then instant session will take place

Instantation means some memory space will be occupied during the runtime of the code against the objects as we are going to define under the classes

So class is one blueprint and object is the instant session of a class

So there is a basic concept. So now let us go for the discussion on them

What are the classes? A class is the internal structure or blueprint of an object

the syntax to define one class is class this a keyword and then we're having this class

name within Caldibrasis will be having the member variables and the member functions

these member variables may be having the same or different data types and they will decide

that what kind of data and for what this data will be stored there and this member functions

will be defining or will be allowing us to do some legitimate operations on those variables so member variables are there to store some data of same or different data types and member functions are defining that what are the permitted operations that we can carry out

on those data. A class will contain some member variables and member functions and members can be

accessed throughout the inter class and sometimes from the outside of the class also

When we define one class, no memory space is going to get off

So this is our way to define one class. Now what are the, what are the respective objects

An object is an instance of the defined class type. When a class is defined, no memory space is allocated, but whenever object is defined

memory spaces are getting allocated. We can say that the classes are the user defined data types, and the objects are the variables

of that type. very basic concept so classes are nothing but use the different data types and

objects are nothing but the variables defined under those data types in Java

we need to initialize objects by the keyword new and syntax for creating an

object will be like this so that is a class name then the object name is equal to

new and the constructor of the class that is a class name constructor so this

the syntax and here we are using the keyword new For the better understanding let us go for one practical demonstration to show you that how to define classes and objects in our Java program in this demonstration we shall discuss class and object

in Java so here the name of the class is student and this particular class is having three

member variables of the student class and their string name i nt id and string major so as here

we haven't mentioned them that they are under a private score of public scope that means

they are in the default scope so here we're having one method the name of the

method is set name from the name of the method it is quite obvious that it will

take one string as input and which will set the name instance variable here

and similarly for set major it takes a string as input argument and it

initializes the major instance variable and the display method is actually printing the name ID and the major and in this way all the three instance

variable contents will get printed using this display method so here the name of the

program is class object or Java you can find that this particular class is having

class object or Java you can easily find that in the same Java source code we

have declared two classes one is a class student and the one is the class class

object so what will happen if we define multiple classes in the same Java program

in the same Java source code then one of the classes will be of the type will be

will be under the scope public and main function will be defined in one of the classes only So this public static void main string array arcs and here we have defined two objects under the

student class and those two objects have got instantiated, memory spaces have got allocated

and they have got instantiated by using new student class constructor. Now we are using the set name, we are using the set major to initialize the name and

the major instance variables and directly were writing s1. ID is equal to

1 021 to instantiate or to initialize this ID instance variable. So similarly we have

done the same for the s2. S2 is another object under the class student and which has got

instantiated using the constructor of the student class. And now we are going for

the s1.2. Display methods. So let us go for the s1. display and s2

for the output so the student name joy has been printed the student ID

one zero to one a major subject here computer science and in this case the name

and the ID and the subject has got printed and they have got printed after

calling the method is one dot display method and s2 dot display method so in this

way we have discussed that how the Java in case of Java how we can

define one class and then how to define objects under the class and access class members thanks for watching this video