02_OOP.md

Java OOPs Concepts

Aim of object-oriented Programming

: to implement real-word entities, for example, object, classes, abstraction, inheritance, polymorphism, etc.

OOPs (Object-Oriented Programming System)

Object means a real-world entity, and OOP is a methodology or paradigm to design a program using classes and object.

Object

• any entity that has state and behavior is know as an object

• can be defined as an instance of a class

• can communicate without knowing the details of each other's data or code

  -> the only necessary thing is the type of message accepted and the type of response returned by the objects

Class

• collections of object is called class
• does not consume any space

Inheritance

• provides code re-usability
• used to achieve runtime polymorphism

Polymorphism

• If one task is performed in different ways, it is known as polymorphism

• In Java, we use method overloading and method overriding to achieve polymorphism

Abstraction

• Hiding internal details and showing functionality is know as abstraction
• In Java, we use abstract class and interlace to achieve abstraction

Encapsulation

• Binding (or wrapping) code and data together into a single unit are known as encapsulation
• A Java class is the example of encapsulation
• Java bean is the fully encapsulated class since all the data members are private here