Inheritance in Java

First, the question comes in our mind, what is inheritance? Thus, this article will show you the definition of inheritance, its meanings, and its types. Let us start with understanding the concept of inheritance.

Definition of inheritance

Inheritance is the procedure in which one class access the properties of another class known as a subclass. For instance, the kid inherits or gains the features, manners, and characteristics of his/her parents. With the inheritance concept, we can just reuse the methods and properties of the existing class. Thus, inheritance provides the reusability feature and is an essential property of OOPs.

Example:

class Parentclass extends Childclass 
{ 
   //methods and fields 
}

Now if you are clear with the meaning and concept of inheritance, let us move ahead to the types of inheritance.

Different types of inheritance

There are Two Types of Inheritance

Single Inheritance
Mulilevel Inheritance
Multiple Inheritance
Hierarchical Inheritance
Hybrid Inheritance

Single Inheritance:

In the concept of single inheritance, one class provides an extension to another class (only one class). It simply means that class A extends to class B. In such a way, Class B extends only class A. This way class A is known as a superclass and class B is known as the subclass.

Multilevel Inheritance:

In this, one class can access and inherit properties from the derived class. Thus, the derived class becomes the base class for the new class. For instance, class C is considered as the subclass of B and B is the subclass of class A.

Hierarchical Inheritance:

In this concept of hierarchical inheritance, one class is inherited by many subclasses. For instance, class A, B, and C inherit the same class D.

Multiple Inheritance:

In the concept of multiple inheritances, one class extends more than one class. Hence, Java is not able to support multiple inheritances. For instance, class C extends both class A and class B respectively.

Hybrid Inheritance:

It is just a combination of single and multiple inheritances. For instance, all the protected and public members of class A are inherited into the class D, first through class B and another through class C.

Applications of Java Inheritance

In Java, when an ‘I-A’ relationship occurs between the two classes we use inheritance.
The parent class is defined as the superclass and the inherited class is known as the superclass.
The ‘extend’ keyword is used by the subclass for inheriting the features of the superclass.
Inheritance is essential since it focuses on reusability of code.

Syntax:

class subClass extends superclass
{
    //fields and method declaration
}

Example:

class Doctor
{
    Void Doctor_details(){
        System.out.println(“doctor Details…..”);
}
}
Class surgeon extends Doctor 
{
    Void Surgeon_details()
    {
        System.out.println(“surgeon details…”);
    }
}
Public class Hospital
{
    Public static void main(String args[])
    {
        Surgeon s = new Surgeon();
        s.doctor_details();
        s.Surgeon_details();
    }
}

Super keyword

The keyword ‘super’ is similar to the ‘this’ keyword. The keyword ‘super’ can be helpful and useful for accessing any data member or methods of the parent class. The super keyword can be utilized at method, variable and constructor level.

Syntax

Super <method name>();

Inheritance with the example and concept of OOPs

let us consider the same application of banking from the earlier instances. We are supposed to open the two distinct types of accounts, one for saving and another for checking which is also recognized as the current saving.

The two types of accounts are:

Current and checking account
Saving account

Then, compare and study the approach of coding from the object-oriented and structured perspective of programming. The approach of structural programming, we will make two functions –

For the deposit action
One to withdraw

Thus, the working of these functions stays the same in all the accounts.

Approach of OOPs

Using the approach of OOPs, we can make two classes.

Each has the execution of the withdraw and deposit functions
This will reduce extra work.

Request for change in the software

Now there is the requirement of change in the specification for the thing which is so known in the software company. You are supposed for adding the functionality of privileged account of banking with the facility. For the background, the overdraft is the feature where you can withdraw any amount available in the balance of your account.

Structured approach

Using the approach functionally, you need to edit the function, that is baselined and tested. Ass the methods and fields will take care of such new requirements.

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General

Inheritance in Java