What is meant by inheritance and types of inheritance?

Answer 1

In advanced programming languages, the re-usability of a portion of code capable of performing a given function is an unique advantage. The compartmentalization of a code which can be reused later and invoked by the class name is referred as object inheritance. In classical inheritance classes are used while in object inheritance sub classes and super classes are add-on features. It saves lengthy redundant coding by inherting the desired code function and calling it by name .

-JP Morgan

Answer 2

Inheritance is the Java object oriented feature wherein functionality in one class is inherited or available for use in another class. It can be compared to parent-child relationships.

1. Single Inheritance

A Scenario where one class is inheriting/extending the behavior of just one super class.

Ex: public class Ferrari extends Car {…}

2. Multilevel Inheritance

A Scenario where one class is inheriting/extending the bahavior of another class which in turn is inheriting behavior from yet another class.

Ex: public class Automobile {…}

Public class Car extends Automobile {…}

Public class Ferrari extends Car {…}

This multilevel inheritance actually has no limitations on the number of levels it can go. So as far as java goes, it is limitless. But for maintenance and ease of use sakes it is better to keep the inheritance levels to a single digit number.

3. Multiple Inheritance

Actually, java does not support multiple inheritance. You can achieve partial multiple inheritance using interfaces but java is not like C or C++ where you can do direct multiple inheritance. However, you can achieve partial multiple inheritance with the help of interfaces.

Ex: public class FerrariF12011 extends Ferrari implements Car, Automobile {…}

And this is under the assumption that Car and Automobile are interfaces.

Here if you see, though you don't inherit concrete code from the Car or the Automobile interface, you do inherit skeleton methods that determine the way your class eventually behaves and hence this can be considered partial Multiple Inheritance.

Answer 3

Types of Inheritance:

1. Single Inheritance

A Scenario where one class is inheriting/extending the behavior of just one super class.

Ex: public class Ferrari extends Car {…}

2. Multilevel Inheritance

A Scenario where one class is inheriting/extending the bahavior of another class which in turn is inheriting behavior from yet another class.

Ex: public class Automobile {…}

Public class Car extends Automobile {…}

Public class Ferrari extends Car {…}

This multilevel inheritance actually has no limitations on the number of levels it can go. So as far as java goes, it is limitless. But for maintenance and ease of use sakes it is better to keep the inheritance levels to a single digit number.

3. Multiple Inheritance

Actually, java does not support multiple inheritance. You can achieve partial multiple inheritance using interfaces but java is not like C or C++ where you can do direct multiple inheritance. However, you can achieve partial multiple inheritance with the help of interfaces.

Ex: public class FerrariF12011 extends Ferrari implements Car, Automobile {…}

And this is under the assumption that Car and Automobile are interfaces.

Here if you see, though you don't inherit concrete code from the Car or the Automobile interface, you do inherit skeleton methods that determine the way your class eventually behaves and hence this can be considered partial Multiple Inheritance.

4. Hybrid Inheritance

This is the scenario wherein your java code exhibits traits of more than one of the inheritance types explained above. Going with the example above again:

Public class FerrariF12011 extends Ferrari implements Car, Automobile {…}

The above is a combination of both single and multiple inheritance.