JAVA INHERITANCE

inheritance in java







Inheritance in Java is a mechanism in which one object acquires all the properties and behaviors of a parent object. It is an important part of OOps(Object Oriented programming system.

Inheritance represents the IS-A relationship which is also known as a parent-child relationship.

Why use inheritance in java

  • For Method Overriding(so runtime polymorphism can be achieved).
  • For Code Reusability.


The syntax of Java Inheritance


  1. class Subclass-name extends Superclass-name  
  2. {  
  3.    //methods and fields  
  4. }  

The extends keyword indicates that you are making a new class that derives from an existing class. 

In the terminology of Java, a class which is inherited is called a parent or superclass, and the new class is called child or subclass.



Types of inheritance in java

On the basis of class, there can be three types of inheritance in java: single, multilevel and hierarchical.

In java programming, multiple and hybrid inheritance is supported through interface only. We will learn about interfaces later.

Types of inheritance in Java


:


Multiple inheritance in Java

Single Inheritance 

When a class inherits another class, it is known as a single inheritance.




Multilevel Inheritance 

When there is a chain of inheritance, it is known as multilevel inheritance.

A Java class can't extends more than one class at time , hence Java won't provide support for multiple inheritance with respect to class.


Hierarchical Inheritance 

When two or more classes inherits a single class, it is known as hierarchical inheritance


Tips -
1) A class can only extends one parent class.

2) A class can implement more than one interfere.

3) interface can extends more than two interface.


Why multiple inheritance is not supported in java?

To reduce the complexity and simplify the language, multiple inheritance is not supported in java.

Consider a scenario where A, B, and C are three classes. The C class inherits A and B classes. If A and B classes have the same method and you call it from child class object, there will be ambiguity to call the method of A or B class.

Eg

class Animal {

  // methods and fields

}

// use of extends keyword

class Dog extends Animal {

  // methods and fields of Animal

  // methods and fields of Dog

}



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