What is an object and class in java

1. WHAT IS AN OBJECT
 Objects are key to understanding object-oriented technology. Look around right now and you will find many
examples of real-world objects: your dog, your desk, your television set, your bicycle etc.
 An Objects are real world entities. Anything you can describe in this world is an object.

2. Object: Object is an instance of class, object has state and behaviours.
An Object has three characteristics:
State
Behaviour
Identity
WHAT IS AN OBJECT

3. Mobile
Object
Cost
Calling
Characteristics
Behavior
Model-No
Company-Name
Operating-System
SMSING
IMEI
Identity:
WHAT IS STATE OF THE OBJECT?

4. WHAT IS STATE OF THE OBJECT?
 What is state of the Object?
 The data present inside object of a class at that point of time is known as state of the
object.
 What is behavior of the object?
 The functionalities associated with the object => Behaviour of the object.
 The state of the object changes from time-to-time depending up on the functionalities
that are executed on that object but whereas behaviour of the object would not change

5. House
Map
Map
contains
Logical
model
for
creating
a
house
WHAT IS A CLASS

6. Physical existence Logical existence
Class is a Logical model for creating an Object
WHAT IS A CLASS

7. Student
Class
Name
Age
Color
Sex
Eating
Drinking
Running
Studing
State
Behavior
Name:Scott
Age:10
Color:White
Sex:Male
State
 Scott can eats less food
 Scott can drink less water
 Scott can’t run fast
 Scott read’s more
Behavior
State
Name:john
Age:20
Color:black
Sex:Male
Behavior
 john can eats more food
 Scott can drink more water
 Scott can’t run fast
 Scott read’s less
Object
STUDENT CLASS IS THE BLUEPRINT FROM WHICH INDIVIDUAL OBJECTS CAN BE CREATED.

8. BIRD CLASS IS THE BLUEPRINT FROM WHICH INDIVIDUAL BIRD OBJECTS CAN BE CREATED.
Bird
Class
Name
color
canSwim
avgLifeTime
weight
Fly
walk
Characteristics
Behavior
Name:sparrow
Color:brown
canSwim:No
avgLifeTime:3Y
Weight:0.34
State
 fly() :30k/h
 walk():1K/h
Behavior
State
Name:penguin
Color:white & black
canSwim:Yes
avgLifeTime:20Y
Weight:15k.g
Behavior
 fly() :can’t fly
 walk():3 to 4 K/h
Object

9. WHAT IS CLASS?
 A class is a specification or blue print or template of an object.
 Class is a logical construct; an object has physical reality.
 Classes provide a means of bundling data and functionality together.
 Class is the base for encapsulation.
 Class will act as the base for encapsulation and implement the concept of
encapsulation through objects.
 Class contains variables and methods.

10. HOW TO DEFINE A CLASS IN PYTHON
 We can write a class to represent properties (attributes) and actions (behaviour)
of object.
 Properties can be represented by variables.
 Actions can be represented by Methods.
 We can define a class by using class keyword.
class <class-name>:
Properties
Behaviour

11. HOW TO CREATE AN OBJECT IN PYTHON
 To create an object, we need a class.
 The syntax for creating an object is "<classname>()", where <classname> is the
name of the class.
 For example, the below code creates three Student objects:
Student()
Student()
Student()

12. WHAT IS A REFERENCE VARIABLE
 Just like we need variables to access and use values, we need variables to access
and reuse the objects that we create. Such variables that are used to access
objects are called reference variables .
 Reference variable is a variable which would be representing the address of the
object.
 Reference will act as a pointer and handler to the object.
 By using reference variable, we can access properties and methods of object.

13. WHAT IS A REFERENCE VARIABLE
Example: -
Suppose there is a class named Person, then see how to create its object.
p = Person ()

14. WHAT IS A REFERENCE VARIABLE
Example: -
Suppose there is a class named Customer, then see how to create its object.
c=Customer ()

15. HOW WE CAN REGISTER SERVICE WITH ANGULAR INJECTOR
ProductList ProductDetails
ProductService Injector

16. WHAT IS STATE OF THE OBJECT?
ProductList ProductDetails
AppModule
AppComponent

17. REGISTERING SERVICE IN PRODUTLISTCOMPONENT
Child-1
ProductDetailsComponent
AppModule
AppComponent
ProductListComponent
Child-2
Register
Service

18. REGISTERING SERVICE IN APPCOMPONENT
Child-1
ProductDetailsComponent
AppModule
AppComponent
ProductListComponent
Child-2
Register
Service

19. REGISTERING SERVICE IN APPMODULE
Child-1
ProductDetailsComponent
AppModule
AppComponent
ProductListComponent
Child-2
Register
Service

20. OBSERVABLE
ProductService
GET observable
DB
subscribe
Product List ProductDetails AppComp
……………………

21. WHAT IS COMPONENT?
Metadata
Template Class
View
HTML
Contains the code required
for template
TypeScript
Data & Method
Information
Decorator

22. WHAT IS COMPONENT?
import { Component } from '@angular/core';
@Component({
selector: 'app-root',
templateUrl: './app.component.html’,
styleUrls: ['./app.component.css']
})
export class AppComponent {
title = ‘Angular';
}
templateUrl points to an HTML file that
represents the view for this component
styleUrls points to an CSS file that
represents the style for this component
This is Component Class Which Contains
the code required for template.

23. WHAT IS COMPONENT?
import { Component } from '@angular/core';
@Component({
selector: 'app-root',
templateUrl: './app.component.html’,
styleUrls: ['./app.component.css']
})
export class AppComponent {
title = ‘Angular';
}
templateUrl points to an HTML file that
represents the view for this component
styleUrls points to an CSS file that
represents the style for this component
This is Component Class Which Contains
the code required for template.

24. WHAT IS ANGULAR INTERPOLATION?
Welcome:{{titlle}}
import { Component } from '@angular/core';
@Component({
selector: 'app-root',
templateUrl: './app.component.html',
styleUrls: ['./app.component.css']
})
export class AppComponent {
title = 'Angular-Interpolation-Demo';
}
app.component.ts app.component.html
Data-binding -
From Component to View
Template
we place the component
property name in the view
template, enclosed in double
curly braces:
{{propertyName}}.
This is interpolation in
angular so here evaluate
title property and show
value of title property

25. TOWER OF HANOI PROBLEM-SOLUTION FOR 2-DISC
A
[From]
B
[Using]
c
[To]
1
2

26. TOWER OF HANOI PROBLEM-SOLUTION FOR 2-DISC
A
[From]
B
[Using]
c
[To]
1 2
Move a disc from TowerA to TowerB using TowerC

27. TOWER OF HANOI PROBLEM-SOLUTION FOR 2-DISC
A
[From]
B
[Using]
c
[To]
1
2
Move a disc from TowerA to TowerC

28. TOWER OF HANOI PROBLEM-SOLUTION FOR 2-DISC
A
[From]
B
[Using]
c
[To]
1
2
Move a disc from TowerB to TowerC using TowerA

29. TOWER OF HANOI PROBLEM-SOLUTION FOR 3-DISC
A
[From]
B
[Using]
c
[To]
1
2
3

30. TOWER OF HANOI PROBLEM-SOLUTION FOR 2-DISC
A
[From]
B
[Using]
c
[To]
1 2
3

31. TOWER OF HANOI PROBLEM-SOLUTION FOR 2-DISC
A
[From]
B
[Using]
c
[To]
1
2
3

32. TOWER OF HANOI PROBLEM-SOLUTION FOR 2-DISC
A
[From]
B
[Using]
c
[To]
1
2
3

33. TOWER OF HANOI PROBLEM-SOLUTION FOR 3-DISC
1
[From]
2
[Using]
3
[To]
1
2
3
Tower1 having 3 disc

34. TOWER OF HANOI PROBLEM-SOLUTION FOR 3-DISC
1
[From]
2
[Using]
3
[To]
1
2
3
Step- 1 => [1-3]
Move disc from Tower1 to Tower3

35. TOWER OF HANOI PROBLEM-SOLUTION FOR 3-DISC
1
[From]
2
[Using]
3
[To]
1 2 3
Step- 2 => [1-2]
Move disc from Tower1 to Tower2

36. TOWER OF HANOI PROBLEM-SOLUTION FOR 3-DISC
1
[From]
2
[Using]
3
[To]
1 2
3
Step- 3 => [3-2]
Move disc from Tower3 to Tower2

37. TOWER OF HANOI PROBLEM-SOLUTION FOR 2-DISC
1
[From]
2
[Using]
3
[To]
1
2
3
Step- 4 => [1-3]
Move disc from Tower3 to Tower2

38. TOWER OF HANOI PROBLEM-SOLUTION FOR 3-DISC
1
[From]
2
[Using]
3
[To]
1
2
3
Step- 5 => [2-1]
Move disc from Tower2 to Tower1

39. TOWER OF HANOI PROBLEM-SOLUTION FOR 3-DISC
1
[From]
2
[Using]
3
[To]
1
2
3
Step- 6 => [2-3]
Move disc from Tower2 to Tower3

40. TOWER OF HANOI PROBLEM-SOLUTION FOR 3-DISC
1
[From]
2
[Using]
3
[To]
1
2
3
Step- 7 => [1-3]
Move disc from Tower1 to Tower3

41. TOWER OF HANOI PROBLEM-SOLUTION FOR 3-DISC
Select ref-var-name from Entity-Class-Name ref-var-name

42. DIFFERENCE BETWEEN SERVLET AND JSP
Servlet JSP
1. If we want to develop web application by using
Servlet Technology then We need to know the
good Knowledge of java.
1. If we want to develop web application by using JSP
Technology then We don't need to know the good
Knowledge of java.
2. Servlet =JAVA+HTML
If we develop Web application using Servlet then we
need to embedded HTML code into JAVA Code
2. JSP=HTML+JAVA
If we develop Web application using JSP then we need
to embedded JAVA code into HTML Code
3.When we develop web application using
servlet then servlets are good at the time of
getting requests and processing that requests.
3.When we develop web application using servlet
then JSP are good when we submitting dynamic
response to the client with very good look and feel.

43. Servlet JSP
4. In web application Servlets are basically used for
processing.
4. In web application JSP are basically used for
Presentation.
5. Once We develop the web application using servlet
and then after developing application if we want to
perform some changes in existing servlets then we
must perform recompilation and reloading on to
the
server.
5. Once We develop the web application using JSP
and then after developing application if we want to
perform some changes in existing servlets then it is
not required to perform recompilation and
reloading on to the server because ,JSP pages are
auto loaded and auto compiled.
6.When we develop MVC web application, In MVC
web application Servlet will act as Controller which
is responsible to accepting the request which is
coming from the client.
6.When we develop MVC web application, In MVC
web application JSP Pages will act as View which is
responsible to Presenting the response to the
client.
DIFFERENCE BETWEEN SERVLET AND JSP

44. MVC ARCHITECTURE
Client
Servlet
Controller
JSP
View
Model
DataBase
Server

45. MVC ARCHITECTURE
Client
Container
Logical Connection
Main Server
http://localhost:8090/myjspapp/
welcome.jsp
myjspapp
Welcome
to
MyPage
Welcome.jsp
WEB-INF
classes
Header
Body
Request
Format
Header
Body
Request
Format

46. TOWER OF HANOI PROBLEM-SOLUTION FOR 3-DISC
<web-app>
<servlet>
<servlet-name>welcomeServlet</servlet-name>
<servlet-class>com.gst.servlet.WelcomeServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name> welcomeServlet </servlet-name>
<url-pattern>/welcome</url-pattern>
</servlet-mapping>
</web-app>

47. TOWER OF HANOI PROBLEM-SOLUTION FOR 3-DISC
<web-app>
<servlet>
<servlet-name>welcomeJsp</servlet-name>
<jsp-file>/WEB-INF/classes/welcome.jsp</jsp-file>
</servlet>
<servlet-mapping>
<servlet-name> welcomeServlet </servlet-name>
<url-pattern>/welcome</url-pattern>
</servlet-mapping>
</web-app>

48. TOWER OF HANOI PROBLEM-SOLUTION FOR 3-DISC
Welcome.jsp
JSP Parsing
Welcome.jsp
JSP Page Translated into Servlet
Welcome_jsp.jsp
Servlet
Compilation
welcome_jsp.class
Byte Code Servlet Loading
_jspService(req,res){
--------------------}
Servlet Instantiation

49. TOWER OF HANOI PROBLEM-SOLUTION FOR 3-DISC
 Loading JSP file into Memory(welcome.jsp)
 Translation of JSP Page to Servlet(Translation Phase)[welcome_jsp.java]
 Compilation of Servlet[welcome_jsp.class]