Inheritance

Inheritance

Inheritance

Deriving a new class from existing class is class Inheritance. The main use of Inheritance is reusability.

Syntax:

Class newclass-name extends existing class

{

Datatype variable1,variable2,??

returntype method()

{

----------

----------

}

}

Example :

class CD

{

String title="inheritance";

String author="javayom";

void display()

{

System.out.println ("title is:"+ title);

System.out.println ("author is:"+author);

}

}

class VCD extends CD

{

String newfeature="JAVAYOM BLOG";

void show()

{

System.out.println ("new feature is: "+newfeature);

}

}

class Demo

{

public static void main(String as[])

{

VCD c = new VCD ();

c.show ();

c.display ();

}

}

Output :

new feature is: JAVAYOM BLOG

title is: inheritance

author is: javayom

Explanation :

» When you extend any class all the superclass members becomes members of

subclass.
» With subclass object we can call subclass members as well as superclass

members also.
» With superclass object we can call only superclass members. We can't call

subclass members.

Types of Inheritance :

1. Simple Inheritance
2. Multilevel Inheritance
3. Hierarchal Inheritance
4. Multiple Inheritance
5. Hybrid Inheritance

1.Simple Inheritance :

In this process we can have only one super class and one subclass.

2.Multilevel Inheritance :

The process of deriving of new class from already derived class is called multilevel inheritance.In this ,A is a superclass and two subclasses B,C. C is a subclass and has superclass called A and B.

3. Hierarchal Inheritance :

In this process we have onesuperclass and many subclasses. In this one superclass and many subclasses. In the following diagram, A is superclass and B, C are subclasses.

4.Multiple Inheritance : (not allowed in java)

In this process we have one subclass and many super classes.

 

Note:
» Java doesn't support multiple Inheritance using classes.
» In this one subclass can have many direct super classes.

5.Hybrid Inheritance : (not allowed in java)

It is combination of multilevel and multiple and herarical inheritance.

Note:
» Java doesn't support hybrid Inheritance using classes.