Abstraction in Java and used of abstract class & method in Java

Introduction:-

                 Abstraction in Java and Abstract Class & Method in this tutorial we explain about what is abstraction and also explain about abstract method and abstract class in Java with example. 

What is abstraction?

Abstraction is a process to hiding the certain details from the users and that focus on a  service provide to a users is called Abstraction. For example  a developer create a calculator in Java and that's providing a service addition, subtraction, multiplication and division. When you use a calculator for addition a two number then user get only output of addition he did not know what is working behind the calculation in a program.

Advantage:-

1.      Avoid code duplication and increase reusability.

2.      The size of code is reduce and reduce complexity.

3.      Provide a security of program only require detail is provide to users.

4.      We can able to  perform any type of changes in back side without effecting the end users.  

 

Abstract Class:-

                        Which is used abstract keyword before the class at the declaration time in a Java is called abstract class.  it can have abstract and non abstract methods. It cannot be instantiated.

 

Note:-

1.      We cannot create a object of abstract class

2.      We use both abstract and non abstract methods in a abstract class

3.      We can also use constructor and final method in a constructor in a abstract class.

4.      To use a abstract class, we have inherit in sub class.  

5.      If class has contain a any abstract method in a class then its compulsory to create that class as abstract class.

 

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Syntax:-

                        abstract class_name{

                                --------------------------

                                ----------------------------

                           }

Abstract Methods:-

                                 If two things  different but some of features is same then we use abstract method.

Syntax:- abstract method_name(){}

 

Example:- two car Maruti and Hyundai and  if  both cars is red colour then we create a abstract function colour for both of car extends by super class car.

abstract class Car{

           public abstract void colour();

     }

class Maruti extends Car{

    colour(){

             System.out.println(“The Maruti Car Colour is Red”);

              }

 }

class Hyundai extends Car{

    colour(){

             System.out.println(“The Hyundai Car Colour is Red”);

              }

 }

class Main{

        public static void main(){

             Maruti maruti =new Maruti();  //  creating a reference of the abstract class for using the function of the abstract class.

            Hyundai hyundai = new Hyundai();

              maruti.colour();

             hyundai.colour();

      }

}

 

Output:- The Maruti Car Colour is Red

The Hyundai Car Colour is Red

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