The document discusses abstract classes and interfaces in object-oriented programming. It defines abstract classes as classes that can contain both abstract and non-abstract methods but cannot be instantiated. Interfaces are blueprints of classes that can only contain abstract methods and achieve abstraction and multiple inheritance in Java. The key differences are that abstract classes can contain method implementations while interfaces only contain abstract methods.

2. ABSTRACT CLASS AND
INTERFACE
Topic Name:
OOP
CONCEPT

3. WELCOME
SMITA KUNDU
ASHRAFUL HAQUE
PROHOR
MD MAZHARUL ISLAM
TANBIR AHMED RABIN
171-15-8555
171-15-9181
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4. CONCEPT:
OBJECT ORIENTED PROGRAMING
Object Oriented Programming is a paradigm that
provides many concepts such as inheritance, data
binding, polymorphism etc.
The programming paradigm where everything is
represented as an object, is known as truly object-
oriented programming language.
Object-Oriented Programming is a methodology or
paradigm to design a program using classes and
objects.

5. CONCEPT:
OBJECT ORIENTED PROGRAMING
Object-Oriented Programming simplifies the software
development and maintenance by providing some concepts:
Object
Class
Inheritance
Polymorphism
Abstraction
Encapsulation

6. CONCEPT:
OBJECT ORIENTED PROGRAMING
Object
Any entity that has state and behavior is known as an object.
For example: chair, pen, table, keyboard, bike etc. It can be
physical and logical.
Class
Collection of objects is called class. It is a logical entity.
Inheritance
When one object acquires all the properties and behavior's of
parent object.

7. CONCEPT:
OBJECT ORIENTED PROGRAMING
Polymorphism
When one task is performed by different ways i.e. known as
polymorphism.
Abstraction
Hiding internal details and showing functionality is known as
abstraction.
Encapsulation
Binding (or wrapping) code and data together into a single unit
is known as encapsulation.

8. CONCEPT:
ABSTRACTION
Abstraction is a process of hiding the implementation
details and showing only functionality to the user.
Another way, it shows only important things to the
user and hides the internal details for example
sending sms, you just type the text and send the
message. You don't know the internal processing
about the message delivery.

9. WAYS TO ACHIEVE
ABSTRACTION
There are two ways to achieve abstraction in java
 Abstract class (0 to 100%)
 Interface (100%)

10. CONCEPT:
ABSTRACT CLASS
A class that is declared with abstract keyword, is
known as abstract class in java.
It can have abstract and non-abstract methods
(method with body).

11. CLASS
ABSTRACT CLASS
A class that is declared as abstract is known as abstract class.
It needs to be extended and its method implemented.
It cannot be instantiated.

12. FEATURES:
ABSTRACT CLASS
Abstract class can have abstract and non-abstract methods.
Abstract class doesn't support multiple inheritance.
Abstract class can have final, non-final, static and non-static
variables
Abstract class can provide the implementation of interface.
The abstract keyword is used to declare abstract class.

13. SYNTAX :
ABSTRACT CLASS
public abstract class Shape{
public abstract void draw();
}

14. SYNTAX :
ABSTRACT METHOD
abstract void cow();//no body and abstract
abstract void pet();//no body and abstract
abstract void dog();//no body and abstract
abstract void printStatus();//no body and abstract

15. EXAMPLE:
ABSTRACT CLASS AND METHOD
abstract class Bike{
abstract void run();
}
class Honda4 extends Bike{
void run(){
System.out.println("running safely..");
}
public static void main(String args[]){
Bike obj = new Honda4();
obj.run();
}
}

16. EXAMPLE:
ABSTRACT CLASS AND METHOD
abstract class Shape{
abstract void draw();
}
class Rectangle extends Shape{
void draw(){ System.out.println("drawing rectangle");
}
}
class Circle1 extends Shape{
void draw(){ System.out.println("drawing circle");
}
}
class TestAbstraction1{
public static void main(String args[]){
Shape s=new Circle1();
s.draw(); }
}

17. CONCEPT:
INTERFACE
An interface in java is a blueprint of a class. It has
static constants and abstract methods.
The interface in java is a mechanism to achieve
abstraction. There can be only abstract methods in the
java interface not method body. It is used to achieve
abstraction and multiple inheritance in Java.
Java Interface also represents IS-A relationship.
It cannot be instantiated just like abstract class.

18. USES:
INTERFACE
There are mainly three reasons to use interface.
They are given below.
It is used to achieve abstraction.
By interface, we can support the functionality of multiple
inheritance.
It can be used to achieve loose coupling.

19. SYNTAX:
INTERFACE
public interface vehicle {
void print() {
}
}

20. EXAMPLE:
INTERFACE
interface Drawable{
void draw();
}
class Rectangle implements Drawable{
public void draw(){System.out.println("drawing rectangle");}
}
class Circle implements Drawable{
public void draw(){System.out.println("drawing circle");}
}
class TestInterface1{
public static void main(String args[]){
Drawable d=new Circle();//In real scenario, object is provided by method e.g. getDrawable()
d.draw();
}}

21. RELATIONSHIP BETWEEN
CLASS AND INTERFACE

22. EXAMPLE:
MULTIPLE INHERITANCE
INTERFACE
interface Printable{
void print();
}
interface Showable{
void show();
}
class A7 implements Printable,Showable{
public void print(){System.out.println("Hello");}
public void show(){System.out.println("Welcome");}
public static void main(String args[]){
A7 obj = new A7();
obj.print();
obj.show();
}
}

23. RELATIONSHIP BETWEEN
MULTIPLE INHERITANCE
INTERFACE

24. DIFFERENCE BETWEEN
ABSTRACT CLASS AND INTERFACE