Hybrid Inheritance in Java

Understanding Hybrid Inheritance in Java
Understanding Hybrid Inheritance in Java

Introduction

Java is an object-oriented programming language. Everything in Java is an object, all the programs, codes, and data reside within classes and objects.  Inheritance, Polymorphism, Encapsulation, Abstraction, classes, and objects are few important concepts of Object-Oriented Programming.  OOPs is a really important topic from an interview perspective.

As in real life, a child inherits some features from its parents; Similarly, in Object Oriented Programming language, a class may inherit from its parent class. In Java, every class has a superclass/parent class. The Object class is the root of the entire class hierarchy in Java.

This blog will discuss hybrid inheritance in Java in detail, along with codes and examples.

Inheritance

Inheritance is a crucial part of object-oriented programming. The process of inheriting the properties and behavior of an existing class into a new class is known as inheritance. We will reuse the original class methods and fields in a new class when we inherit the class. Inheritance may also be described as the Is-A relationship, also known as the parent-child relationship.

A real-world example of Inheritance is a relationship between a daughter and her Mother. A daughter inherits features from her mother, the mother, in turn, has inherited the features from her mother, and the cycle goes on. A technical example of inheritance is as follows: The Integer Class is the child class of the Number class. The Number class is the Child Class of the Object Class.

Java supports the following types of inheritance:

  1. Single Inheritance
  2. Multi-level Inheritance
  3. Hierarchical Inheritance
  4. Hybrid Inheritance
  5. Multiple Inheritance(not support by using classes, but its possible using interfaces)

You must check out our blog “Inheritance in Java” to better understand Inheritance before moving to hybrid inheritance in Java.

Hybrid inheritance in Java

Hybrid inheritance in Java is a combination of two or more types of inheritances. The purpose of using hybrid inheritance in Java is to modularize the codebase into well-defined classes and provide code reusability.

This blog will discuss hybrid inheritance in Java using a combination of the following inheritances:

  1. Hybrid Inheritance in Java using Single and Multiple Inheritance.
  2. Hybrid Inheritance in Java using Multilevel and Hierarchical Inheritance

Hybrid Inheritance in Java using Single and Multiple Inheritance

Consider the following example wherein a combination of single and multiple inheritances is used to achieve hybrid inheritance in Java:

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There is a HumanBody class that has some functionality like eating(), walking(), dancing(), etc., and some fields like bloodPressure, normalOxygenLevel, bonesCount, etc. There are two child classes of the HumanBody class, the Female and Male class. The Male class and the Female class will inherit all the functions and the fields of the HumanBody class. This is a simple example of Single Inheritance in Java. 

single_inheritance

Now consider that the Male and Female classes have a child with the class name as Child. This is a simple example of multiple inheritances in Java. The relationship between the Male, Female, and Child classes is visualized below:

multiple_inheritance

The combined relationship between the HumanBody, Male, Female, and Child classes is visualized below. It is an example of Hybrid Inheritance using the combination of Single and Multiple Inheritances.

However, wait, we know that multiple inheritances are not possible in Java. So this analogy has to be incorrect. 

Well, the only incorrect thing is that, instead of classes, interfaces will be used to achieve multiple inheritances.

Syntax

public class A
{
    // Methods and Fields of class A
}
public interface interfaceB 
{
  // Methods and Fields of InterfaceB
}
public interface interfaceC 
{
  // Methods and Fields of InterfaceC
}
public class D extends A implements InterfaceB,InterfaceC
{
    // Implementation of the method defined in Interfaces, InterfaceB and InterfaceC

    // Methods of class D
   
}

The below program demonstrates hybrid inheritance using a combination of single inheritance and multiple inheritances using Interfaces.

class HumanBody
{
   public void displayHuman()
   {
     System.out.println("Method defined inside HumanBody class");
   }
}
interface Male
{
 public void show();
}
interface Female
{
 public void show();
}
 
// Single Inheritance is the relationship between Child // class and HumanBody class.
// Implementing Male and Female interface is Multiple // Inheritance
public class Child extends HumanBody implements Male, Female
{
 public void show()
 {
   System.out.println("Implementation of show() method defined in interfaces Male and Female");
 }  
 
 public void displayChild()
 {
   System.out.println("Method defined inside Child class");
 }
 
 public static void main(String[]args)
 {
   Child obj = new Child();
   System.out.println("Implementation of Hybrid Inheritance in Java");
   obj.show();
   obj.displayChild();
 }
}

The output of the above program is:

Implementation of Hybrid Inheritance in Java
Implementation of show() method defined in interfaces Male and Female
Method defined inside Child class

Hybrid Inheritance in Java using Multilevel and Hierarchical Inheritance

Hybrid Inheritance can also be achieved using a combination of Multilevel and Hierarchical inheritance. A real-world example will be, Son class inherits the Father class, Father class inherits the GrandFather class. This relation is of Multilevel inheritance. Likewise, A Daughter Class inherits the Father class, which in turn inherits the GrandFather class.

On the other hand, Son and Daughter both inherit Father class, and this relation is of Hierarchical Inheritance.

A combination of both the inheritance relation will make Hybrid inheritance.

The below program demonstrates Hybrid inheritance using a combination of Multilevel and Hierarchical inheritance.

class GrandFather
{
 public void printGrandFather()
 {
   System.out.println("GrandFather's class");
 }
}
 
class Father extends GrandFather
{
 public void printFather()
 {
   System.out.println("Father class has inherited GrandFather class");
 }
}
 
class Son extends Father
{
 public Son()
 {
   System.out.println("Inside the Son Class");
 }
 
 public void printSon()
 {
   System.out.println("Son class has inherited Father class");
 }
}
 
class Daughter extends Father
{
 public Daughter()
 {
   System.out.println("Inside the Daughter Class");
 }
 
 public void printDaughter()
 {
   System.out.println("Son class has inherited Father class");
 }
}
 
public class HybridInheritance
{
 public static void main(String[]args)
 {
   Son obj = new Son();
   obj.printSon();  // Accessing Son class method
   obj.printFather();  // Accessing Father class method
   obj.printGrandFather();  // Accessing GrandFather class method
 
   Daughter obj2 = new Daughter();
   obj2.printDaughter();  // Accessing Daughter class method
   obj2.printFather();    // Accessing Father class method
   obj2.printGrandFather();   // Accessing GrandFather class method
 
 
 }
}

The output of the above program is:

Inside the Son Class
Son class has inherited Father class
Father class has inherited GrandFather class
GrandFather's class
Inside the Daughter Class
Son class has inherited Father class
Father class has inherited GrandFather class
GrandFather's class

Frequently Asked Questions

What are the different types of hybrid inheritance?

Hybrid Inheritance in Java is a combination of two or more inheritances. It can be done using a combination of the following inheritances.
1. Single and Multiple Inheritance
2. Multilevel and Hierarchical Inheritance

Why is there no hybrid inheritance in java?

Java supports hybrid Inheritance. However, Java does not support Multiple Inheritance with classes, so in order to achieve hybrid inheritance, multiple inheritances with classes should not be used. Multiple Inheritance with Interfaces is possible.

What is hybrid inheritance?

The combination of two or more inheritances is called hybrid inheritance. It provides code reusability.
Refer to the blog for more details.

Why are pointers not used in Java?

Java is a highly secured programming language. Pointers provide direct access to a memory address, and an arbitrary memory location can be accessed, and read and write operations can be performed on it. For the purpose of security Java does not support Pointers.

Key Takeaways

This blog discussed Hybrid Inheritance in Java in detail. With this done, you may now switch to learn more about Object-Oriented Programming concepts. 

Questions related to Inheritance are frequently asked in technical rounds of big companies.

Do not stop here !! Feel free to explore Codestudio; it is one of the best platforms wherein you will find structured, guided paths, interview questions listing, blogs curated by experts. Remember, Practice makes perfect !!

By: Manvi Chaddha