inheritance in java with example programs pdf | advantages of inheritance in java

Inheritance in Java

Inheritance is an important pillar of OOP(Object Oriented Programming). It is the mechanism in java by which one class is allow to inherit the features(fields and methods) of another class.

The idea behind inheritance in Java is that you can create new classes that are built upon existing classes. When you inherit from an existing class, you can reuse methods and fields of the parent class. Moreover, you can add new methods and fields in your current class also.

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

Important terminology:

·         Super Class: The class whose features are inherited is known as super class(or a base class or a parent class).

·         Sub Class: The class that inherits the other class is known as sub class(or a derived class, extended class, or child class). The subclass can add its own fields and methods in addition to the superclass fields and methods.

·         Reusability: Inheritance supports the concept of “reusability”, i.e. when we want to create a new class and there is already a class that includes some of the code that we want, we can derive our new class from the existing class. By doing this, we are reusing the fields and methods of the existing class.

How to use inheritance in Java

·         The keyword used for inheritance is extends. 

 Syntax :

                   class derived-class extends  base-class

                                {

                          //method and fields

                                        }

Why use inheritance in java

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

The extends keyword indicates that you are making a new class that derives from an existing class. The meaning of "extends" is to increase the functionality.

Java Inheritance Example

inheritance in java programming

class Employee{  

 float salary=40000;  

}  

class Programmer extends Employee{  

 int bonus=10000;  

 public static void main(String args[]){  

   Programmer p=new Programmer();  

   System.out.println("Programmer salary is:"+p.salary);  

   System.out.println("Bonus of Programmer is:"+p.bonus);  

}  

}  

Output:

Programmer salary is:4000.0

Bonus of Programmer is:10000

Type of inheritance in java

There are  three types of inheritance in java:

1)   single

2)   multilevel

3)    hierarchical.