Object Oriented Programming System java

OOPs (Object Oriented Programming System):

Object means a real-world entity. Object-Oriented Programming is a methodology or paradigm used to design a program using classes and objects. The primary purpose of object-oriented programming is to increase the flexibility and maintainability of programs

It simplifies the software development and maintenance by providing some concepts like

• Inheritance
• Polymorphism
• Abstraction
• Encapsulation

Object-Oriented Programming features:

First let us discuss what is class and Object before going to oops features

Object: Any entity that has state and behavior is known as an object.It is a bundle of data and its behaviour(often known as methods).

Examples of states and behaviors:

Object: House

State: Address, Color, Area

Behavior: Open door, close door

So if I had to write a class based on states and behaviors of House. I can do it like this: States can be represented as instance variables and behaviors as methods of the class. We will see how to create classes in the next section of this guide.

Class:A class can be considered as a blueprint using which you can create as many objects as you like. For example, here we have a class Machine that has two data members (also known as fields, instance variables and object states). This is just a blueprint, it does not represent any Machine, however using this we can create Machine objects (or instances) that represents the Machine activities.

Example to understand  class and object

public class Machine {
  //fields (or instance variable)
  String machineName;
  int machineAge;

  // constructor
  Machine(String name, int age){
     this.machineName = name;
     this.machineAge = age;
  }
  public static void main(String args[]){
     //Creating objects
     Machine obj1 = new Machine("Crusher", 5);
     Machine obj2 = new Machine("Mixer", 18);

    //Accessing object data through reference
    System.out.println(obj1.machineName+" "+obj1.machineAge);
    System.out.println(obj2.machineName+" "+obj2.machineAge);
  }
}

Output: Crusher 5
Mixer 18