Inheritance In Java

Khawar Islam
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Article

Introduction

I am discussing one of the most importnat pillars of object oriented programming which is known as inheritance. Today, I am giving you the fundamental concept of inheritance likewise how we assume the project needs inheritance relationship.

What is Inheritance

The approach of inheritance is simple. When we add a new class in any language and there already existsa class that includes some of the code that you need, you can derive your new class from the existing class. By doing this, we can reuse the fields and methods of the existing class.
Inheritance provides a powerful mechanism for organizing and structuring the software.

How we assume Inheritance

The best approach of assuming inheritance is that you first complete paper work which means you draw all types of diagram ERD, Dataflow and etc. and then make a function which is used in inheritance.
After completing paper work now you assume that the similar things which are used again and again in project you mark on it.

Scenario of Selling Store

Consider a scenario: I am a developer and one client comes who is a shop seller selling different types of things and he asks me to build a system which performs some functionalities, then he tell me the fundamentals of the shop. All he asked is that I draw the shape which is necessary for the system and I creted these three diagrams after listening to the list scenario.

Now I see that there are some basic functionalities which are using same class again and again now the time comes to implement OOP concepts on the basic system approach; now I make a basic class and put those functionalities which are similar. Now I draw this type of diagram after assuming OOP concept.

concept

Inheritance terminologies in different languages

Inheritance is done with some keywords; some of the languag of keywords is given below,

Java public class Album extends Product { …
C# public class Album: Product { …
VB.NET public class Album inherits Product { …
Ruby public class Album > Product { …
C++ public class: Product { …
Objective-C @interface class Album: Product { …

Calling a method in the Super/Parent/Base Class

This are some method when you call a method in a following class,

Java super.dosomething ();
C# base.dosomething ();
VB.NET Mybase.dosomething();
Ruby super do_something
C++ [super someMethod];
Objective-C NamedBaseClass::dosomething();

Implementation

First I add class A and make method of subtraction and pass two parameter.
I add B Class but now I extend with class A because we need to add the function which is used in class A.
Now in main program file, I make an instance of class B and call the function which is located in Class A, because B Class extends A Class and all the functionalities in class A inherit class B, this is the real benefit of inheritance.