Ch5Inheritance.pptx Java program Java file

Object Oriented Programming Using Java
INHERITANCE
School of Computer Engineering
KIIT Deemed to be University
Dr.Sunil Kumar Gouda
Asst. Professor

01/25/2025 Java Programming, Dr.Sunil Kumar Gouda
Inheriatnce
 Inheritance is the process by which one class can acquire the properties
of another class.
 The class, from which properties are inherited to another class, is known
as super class.
 The class, to which properties are inherited from an existing class, is
known as sub class.
 A sub class inherits all non private variables and methods defined by the
super class and add its own, unique elements.
 To derive a sub class from super class, we use extends keyword.

Inheritance Cont..

Advantages of Inheritance
Inheritance allows the creation of hierarchical classifications of classes.
It allows code reusability feature.
The sub class extends the properties of super classes to create more
dominant objects.

Syntax of Inheritance
The syntax of a class declaration that inherits a super class is :
class subclass-name extends superclass-name
{
// body of the class
}
Point to Remember:
A sub class can access all the public and protected members of a super class,
not the private members. (By default, the variable or functions of a class are
public in nature)

Types of Inheritance
Java supports following types of inheritance:
Single Inheritance
Hierarchical Inheritance
Multiple Inheritance (not supported using class, but supported through
interface)
Multilevel Inheritance
Hybrid Inheritance ( only which not contain Multiple Inheritance)

Single Inheritance
In single inheritance, we have only one super class and one sub class.
The subclass inherits properties from the only super class.
 Syntax of single inheritance:
class superClass
{
// Body of super class
}
class subClass extends superClass
{
// Body of sub class
}
Super
Class
Sub
Class

Single Inheritance (Example)
class Rectangle
{
int l, b;
void disp_lb()
{
System.out.println("l= " +l+", b="+b);
}
}
class Cuboid extends Rectangle
{
int h;
void disp_h()
{
System.out.println("h= " +h);
}
void find_volume()
{
System.out.println ("Volume= "+l*b*h);
}
}
class SingleInheritance
{
public static void main(String args[])
{
Cuboid c=new Cuboid();
c.l=9;
c.b=7;
c.h=3;
c.disp_lb();
c.disp_h();
c.find_volume();
}
}
Output:
l=9, b=7
h=3
Volume=189

Hierachical Inheritance
In hierarchical inheritance, two or more subclass inherits properties from
a single super class.
 Syntax of hierarchical inheritance:
class superClass
{
// Body of super class
}
class subclass1 extends superClass
{
// body of sub class 1
}
class subclass2 extends superClass
{
// body of sub class 2
}

Hierachical Inheritance (Example)
class Animal
{
void eat()
{
System.out.println("eating...");
}
}
class Dog extends Animal
{
void bark()
{
System.out.println("barking...");
}
}
class Cat extends Animal
{
void meow()
{
System.out.println("meowing...");
}
}
class HierarchicalInheritance
{
{
Cat c=new Cat();
c.meow();
c.eat();
}
}
Output:
meowing...
eating...

Multiple Inheritance
 In multiple inheritance, one subclass inherits properties from two or more
super class. Multiple inheritance is not supported in java.
 Syntax of multiple inheritance:
class super1
{
// Body of super class 1
}
class super2
{
}
// Illegal
class subclass extends super1, super2
{
// Body of sub class
}

Multiple Inheritance Cont..
 In Java, multiple inheritance is not supported using classes due to
ambiguity problem. Ambiguity is a situation where compiler cannot
predicate to inherit which field out of identical fields present in multiple
super classes.
 But same can be achieved using the concept of interface.

Multilevel Inheritance
 In multi level inheritance, number of classes are represented at different
levels.
 Syntax of multilevel inheritance:
class superClass1
{
}
class superClass2 extends superClass1
{
// body of super class 2
}
class subClass extends superClass2
{
// body of sub class
}

Multilevel Inheritance (Example)
class Shape
{
public void display()
{
System.out.println("Inside display");
}
}
class Rectangle extends Shape
{
public void area()
{
System.out.println("Inside area");
}
}
class Cube extends Rectangle
{
public void volume()
{
System.out.println("Inside volume");
}
}
public class Tester
{
public static void main(String[] arguments)
{
Cube cube = new Cube();
cube.display();
cube.area();
cube.volume();
}
}
Output:
Inside display
Inside area
Inside volume

Hybrid Inheritance
 It is the combination of all the above inheritance.

How constructor of a super class gets called ?
 A subclass constructor can call or invoke the constructor of its super
class in two ways:
 A subclass constructor invokes the default or non parameterized
constructor of its super class implicitly or automatically.
 A subclass constructor can invoke the parameterized constructor of its
super class explicitly by using the “super” statement.
 Note: In a class hierarchy, constructors are called in order of derivation,
from super class to subclass.
 super() must be the first statement to be executed in a subclass
constructor to call the parameterized constructor of super class.
 If super() is not used, then the default constructor of super class will be
called.

Invoking default constructor of the super class
class A
{
A()
{
System.out.println("Inside A's
constructor.");
}
}
class B extends A
{
B()
{
System.out.println("Inside B's
constructor.");
}
}
class C extends B
{
C()
{
System.out.println("Inside C's constructor.");
}
}
class CallingCons
{
{
C c = new C();
}
}
Output:
Inside A’s constructor.
Inside B’s constructor.
Inside C’s constructor.

Invoking parameterized constructor of the super class
class Rect
{
int length, breadth;
Rect (int l, int b)
{
length=l;
breadth=b;
}
}
class Cuboid extends Rect
{
double height;
Cuboid (int l, int b, int h)
{
super(l, b);
height=h;
}
void volume()
{
System.out.println (length*breadth*height);
}
}
class Vol
{
{
Cuboid v=new Cuboid(1, 2, 3);
v.volume();
}
}
Output:
6.0

END OF THE CHAPTER

Ch5Inheritance.pptx Java program Java file

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