Inheritance in java

INHERITANCE
In Java
presented by:
Rahul Paul

Inheritance:
In java inheritance is a mechanism which one object can get
all the properties and behaviours of a parent object. In
inheritance there is a relationship between two classes.
That’s why it is-a relationship.
For example: Bike, car, bus this
are vehicle. That’s why the
child of vehicle are bike,
car, bus and vehicle is the
parent of this objects.
Vehicle
Bike, car,
bus

Java inheritance:
• The important of inheritance in java program is code
reusability. We can reuse the function of parent class at
child class.
• In java we use Extends keyword for inheritance.
• Subclass and Superclass in inheritance.

Inheritance Syntax:
class Parent
{
//code
}
class Child extends Parent
{
//code
}
Parent
Child

Simple program
class super {
Public void display()
{
System.out.println(“I am parent class”);
}
}
class sub extends super {
public static void main(String args[])
{
sub message = new sub()
message.display();
}
}
Super
I am from parent class
sub
Parent class
Child classs
Output: I am parent class

TYPES OF INHERITANCE:
 Single inheritance.
 Multiple inheritance.
 Multi-level inheritance.
 Hierarchical inheritance.
 Hybrid inheritance.
Note: In java Multiple inheritance is not supported.

SINGLE INHERITANCE:
Single inheritance is the most easy type to understand. In
single inheritance a class extends another only one class. The
child class inherit only parents class. The subclass inherit the
objects of superclass.
Example: A cat is a animal.
So a cat only can inherit the
objects of animal class.
Animal
(superclass)
Cat
(subclass)

SAMPLE PROGRAM OF SINGLE INHERITANCE :
class message_super {
Public void display()
{
System.out.println(“I am from superclass”);
}
}
class message_sub extends message_super {
{
Message_sub message = new message_sub()
Message.display();
}
}
Output: I am from superclass
message_super
I am from superclass
message_sub

MULTILEVEL INHERITANCE
When a class extends a class, and that class extends another
class and its object then it call multilevel inheritance.
Example: a class A is parent class.
Class B is inherit the
objects of class A. Another
one class c is child of class B.
class c can inherit the objects
of class C.
A
B
C
Base class
Intermediary
class
Child class

SAMPLE PROGRAM OF MULTILEVEL INHERITANCE :
class a {
int data= 15; }
class b extends a {
}
class c extends b {
public void display() {
System.out.println(“number is:”+data);
}
{
c num= new c()
num.display();
}
}
Output: number is: 15
a
Data=15
b
c

HIERARCHICAL INHERITANCE:
When one superclass can be inherited by more than one
subclass then it is called hierarchical inheritance.
Example: a class A is parent class.
Class B is inherit the
objects of class A. Another
one class c also can inherit the
objects of class A.
A
B C

Syntax of Hierarchical inheritance:
Class Food
{
//code
}
class Rice extends Food{
//code
}
class Fruit extends Food{
//code
}
Food
Rice Fruit

Inheritance Method overriding:
When a method is already in parent class but also declaring
in child class, then it is known as Method Overriding.
Note: But when it is ‘Final’ method it cannot overriding.
Example: A parent class of animal
has method ‘eat’. Also a child class
tiger has method ‘eat’.
Animal
eat()
Tiger
eat()

Sample program of method overriding:
class animal {
System.out.println(“I am animal”); }
}
class tiger extends animal {
System.out.println(“I am tiger”);
}
public static void main(String args[]) {
tiger t = new tiger();
t.display(); }
}
Output: I am tiger

Inheritance in java

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