OBJECT ORIENTED PROGRAMING{OOP}

BY SANGA G,

OOP ITRODUCTION

• What is object oriented programming?Object-oriented programming (OOP) is a way to

organize and conceptualize a program as a set of interacting objects.

• The programmer defines the types of objects that will exist.

• The programmer creates object instances as they are needed.

OOP CONT………….

• The programmer specifies how these various object will communicate and interact with each other.

• Object-oriented programming is a methodology that gives programmers tools to make this modeling process easier.

• Simply we can say Object-oriented programming, or OOP, is an approach to problem solving where all computations are carried out using objects.

TEMINOLOGIES USED IN OOP

• Object• Class• Instance• Inheritance• Encapsulation• Abstraction

• Polymorphism• Overloading

Object

• An object is a component of a program that knows how to perform certain actions and how to interact with other elements of the program.

• An object contains both data and methods that manipulate that data– An object is active, not passive; (it does things)– An object is responsible for its own data

Object

• Code in object-oriented programming is organized around objects. Once you have your objects, they can interact with each other to make something happen

• Let's say you want to have a program where a person gets into a car and drives it from A to B. You would start by describing the objects, such as a person and car. That includes methods: a person knows how to drive a car and a car knows what it is like to be driven. Once you have your objects, you bring them together so the person can get into the car and drive.

Class

• A class is a blueprint or template or set of instructions to build a specific type of object.

or• class is the generic definition for a set of

similar objects• A class can be thought of as a template used

to create a set of objects.• A class is a static definition; a piece of code

written in a programming language

Class

• So, let's say you want to use a person in your program. You want to be able to describe the person and have the person do something. A class called 'person' would provide a blueprint for what a person looks like and what a person can do. To actually use a person in your program you need to create an object. You use the person class to create an object of the type 'person.' Now you can describe this person and have it do something.

Class A class is a statement

class ClassVariableattr AttrName1: AttrNameNmeth Pattern1 Statement end:meth PatternN Statement end

end

Instance• An instance is a realization of a particular item of a class. In

other words, an instance is an instantiation of a class. All the instances of a class have similar properties, as described in the class definition. For example, you can define a class called "Student" and create three instances of the class "Student" for "Peter", "Paul" and "Pauline".

• The term "object" usually refers to instance. But it is often used loosely, and may refer to a class or an instance.

• instance is a concrete occurrence of any object, existing usually during the runtime of a computer program

Example of instance For examples, suppose that we have a class called Circle, we can create instances

of Circle as follows:

// Declare 3 instances of the class Circle, c1, c2, and c3

Circle c1, c2, c3; // They hold a special value called null// Construct the instances via new operator

c1 = new Circle(); c2 = new Circle(2.0); c3 = new Circle(3.0, "red");

// You can Declare and Construct in the same statement Circle

c4 = new Circle();

Inheritance

• Inheritance• Inheritance is the process of forming a new

class from an existing class that is from the existing class called as base class, new class is formed called as derived class.

• This is a very important concept of object-oriented programming since this feature helps to reduce the code size.

Example // A class to display the attributes of the vehicle

class Vehicle { String color; int speed; int size; void attributes() { System.out.println("Color : " + color); System.out.println("Speed : " + speed); System.out.println("Size : " + size); } } // A subclass which extends for vehicle class Car extends Vehicle { int CC; int gears; void attributescar() {

Example cont……// The subclass refers to the members of the superclass System.out.println("Color of Car : " + color); System.out.println("Speed of Car : " + speed); System.out.println("Size of Car : " + size); System.out.println("CC of Car : " + CC); System.out.println("No of gears of Car : " + gears); } } public class Test { public static void main(String args[]) { Car b1 = new Car(); b1.color = "Blue"; b1.speed = 200 ; b1.size = 22; b1.CC = 1000; b1.gears = 5; b1.attributescar(); } }

Encapsulation• Encapsulation is placing the data and the

functions that work on that data in the same place. While working with procedural languages, it is not always clear which functions work on which variables but object-oriented programming provides you framework to place the data and the relevant functions together in the same object.

Benefits of Encapsulation• Makes it easy to model real-world entities –

hence easy to understand and maintain• Control the way data is accessed or modified• Makes the class easy to use for clients• Increase reusability• Aids to the flexibility of design e.g. It is

possible to add accelerationConfiguration field in the Car. This will enable you to have different acceleration behaviour of each car.

Abstraction• Polymorphism is the capability of a method to

do different things based on the object that it is acting upon. In other words, polymorphism allows you define one interface and have multiple implementations

Overloading

• Overloading is ability of one function to perform different tasks, i.e,it allows creating several methods with the same name which differ from each other in the type of the input and the output of the function.

Private and public • Public, means all the class members declared under public will be available

to everyone. The data members and member functions declared public can be accessed by other classes too. Hence there are chances that they might change them. So the key members must not be declared public.

exampleclass PublicAccess { public: // public access specifier int x; // Data Member Declaration void display(); // Member Function decaration

}

Private

• Private , means that no one can access the class members declared private outside that class. If someone tries to access the private member, they will get a compile time error. By default class variables and member functions are private.

Methods and properties of the class

• A method in object-oriented programming (OOP) is a procedure associated with a message and an object. An object is made up of data and behavior, which form the interface that an object presents to the outside world. Data is represented as properties of the object and behavior as methods. For example, a Window object would have methods such as open and close, while its state (whether it is opened or closed) would be a property.

Class methods

• Class methods are methods that are called on a class rather than an instance. They are typically used as part of an object meta-model. I.e, for each class defined an instance of the class object in the meta-model is created.

property• property is a member of a class that plays an intermediary role

to a field of the class. For example, if you have a field of class and that member represents the salary of an employee, a property can be the "door" that other classes that need the salary must present their requests to. As such, these external classes cannot just change the salary or retrieve it as they wish. A property can be used to validate their request, to reject or to accept them.

• A property is used to "filter" access to a field of a class. Therefore, you start by declaring a (private (if you don't make it private, you may be deceiving the purpose of creating a property)) field

property

• A property is used to "filter" access to a field of a class. Therefore, you start by declaring a (private (if you don't make it private, you may be deceiving the purpose of creating a property)) field

• https://www3.ntu.edu.sg/home/ehchua/programming/java/J3a_OOPBasics.html

• https://processing.org/examples/inheritance.html

• https://www.tutorialspoint.com/cplusplus/cpp_data_encapsulation.htm