JAVA PROGRAMMING NOTES
PART 2
, MODULE 2
Java OOPs Concepts
Object means a real word entity such as pen, chair, table etc. Object-Oriented Programming is
a methodology or paradigm to design a program using classes and objects. It simplifies the
software development and maintenance by providing some concepts:
o Object o Class o
Inheritance o
Polymorphism o
Abstraction o
Encapsulation
Object
Any entity that has state and behavior is known as an object. For example: chair, pen, table,
keyboard, bike etc. It can be physical and logical.
Class
Collection of objects is called class. It is a logical entity.
Inheritance
When one object acquires all the properties and behaviours of parent object i.e. known as
inheritance. It provides code reusability. It is used to achieve runtime polymorphism.
Polymorphism
When one task is performed by different ways i.e. known as polymorphism. For example: to
convince the customer differently, to draw something e.g. shape or rectangle etc.
In java, we use method overloading and method overriding to achieve polymorphism.
Another example can be to speak something e.g. cat speaks meaw, dog barks woof etc.
Abstraction
Hiding internal details and showing functionality is known as abstraction. For example: phone
call, we don't know the internal processing.In java, we use abstract class and interface to achieve
, A java class is the example of encapsulation. Java bean is the fully encapsulated class because all
the data members are private here.
Advantage of OOPs over Procedure-oriented programming language
• 1)OOPs makes development and maintenance easier where as in Procedure-oriented
programming language it is not easy to manage if code grows as project size grows.
• 2)OOPs provides data hiding whereas in Procedure-oriented programming language a
global data can be accessed from anywhere.
• 3)OOPs provides ability to simulate real-world event much more effectively. We can
provide the solution of real word problem if we are using the Object-Oriented
Programming language.
Java Naming conventions
Name Convention
class name
should start with uppercase letter and be a noun e.g. String, Color, Button, System, Thread etc.
interface name should start with uppercase letter and be an adjective e.g. Runnable, Remote, ActionListener etc.
method name
should start with lowercase letter and be a verb e.g. actionPerformed(), main(), print(), println() etc.
variable name should start with lowercase letter e.g. firstName, orderNumber etc.
should be in lowercase letter e.g. java, lang, sql, util etc.
PART 2
, MODULE 2
Java OOPs Concepts
Object means a real word entity such as pen, chair, table etc. Object-Oriented Programming is
a methodology or paradigm to design a program using classes and objects. It simplifies the
software development and maintenance by providing some concepts:
o Object o Class o
Inheritance o
Polymorphism o
Abstraction o
Encapsulation
Object
Any entity that has state and behavior is known as an object. For example: chair, pen, table,
keyboard, bike etc. It can be physical and logical.
Class
Collection of objects is called class. It is a logical entity.
Inheritance
When one object acquires all the properties and behaviours of parent object i.e. known as
inheritance. It provides code reusability. It is used to achieve runtime polymorphism.
Polymorphism
When one task is performed by different ways i.e. known as polymorphism. For example: to
convince the customer differently, to draw something e.g. shape or rectangle etc.
In java, we use method overloading and method overriding to achieve polymorphism.
Another example can be to speak something e.g. cat speaks meaw, dog barks woof etc.
Abstraction
Hiding internal details and showing functionality is known as abstraction. For example: phone
call, we don't know the internal processing.In java, we use abstract class and interface to achieve
, A java class is the example of encapsulation. Java bean is the fully encapsulated class because all
the data members are private here.
Advantage of OOPs over Procedure-oriented programming language
• 1)OOPs makes development and maintenance easier where as in Procedure-oriented
programming language it is not easy to manage if code grows as project size grows.
• 2)OOPs provides data hiding whereas in Procedure-oriented programming language a
global data can be accessed from anywhere.
• 3)OOPs provides ability to simulate real-world event much more effectively. We can
provide the solution of real word problem if we are using the Object-Oriented
Programming language.
Java Naming conventions
Name Convention
class name
should start with uppercase letter and be a noun e.g. String, Color, Button, System, Thread etc.
interface name should start with uppercase letter and be an adjective e.g. Runnable, Remote, ActionListener etc.
method name
should start with lowercase letter and be a verb e.g. actionPerformed(), main(), print(), println() etc.
variable name should start with lowercase letter e.g. firstName, orderNumber etc.
should be in lowercase letter e.g. java, lang, sql, util etc.
