1. BITS Pilani
Avinash Gautam Department of Computer Science and Information Systems

2. By appointment through mail
Object-Oriented Programming (CS/IS F213)
Avinash Gautam
Chamber# 6121-Y, NAB
Consultation Hour
By appointment through mail

3. Lecture-1 [OOP Basics] Programming Paradigms OOP Concepts
Structured programming
Object oriented programming
OOP Concepts
What is an object?
What is a Class?
What is Inheritance?
What is an Interface? 3

4. Programming Paradigms […1]
High Level Languages (1960)
Large complex programs difficult to manage and maintain
Structured Programming (1970)
Logically structure the program separate smaller more manageable components
Significant problems persisted
Understanding the systems we need to create
Changing existing software as users requirement change
Modular languages (1980)
Modula2 and ADA, precursor to modern OO Languages

5. Programming Paradigms […2]
Object Oriented Paradigm and Component Based Software Development (1990)
Became the norm from 2000 onwards
Lead to the development of software components where the operation of the software and the data it operates on are modeled together
Lead to the development of reusable software components
Save significant development time and cost
Allow better software models to be produced which are more maintainable and easier to understand

6. OOP Concepts 6

7. What is an object? Look around you and identify some objects
Real world objects share two characteristics
They all have state
They all have behavior
Identifying the state and behavior for real-world objects is a great way to begin thinking in terms of object-oriented programming
Two Questions
What possible states can this object be in?
What possible behavior can this object perform?
Write down your observation
Real world objects vary in complexity (Radio, Table Lamp)
Objects may contain other objects
These real world observations all translate into object oriented programming 7

8. What is an object? (Contd.)
Software objects are conceptually similar to real world objects: they too consist of state and related behavior
An object store its state in fields and exposes its behavior through methods
Methods operate on objects internal state and serve as the primary mechanism for object-to-object communication
Hiding internal state and requiring all interaction through an object’s method is known as data encapsulation - a fundamental principle of OOP 8

9. What is an object? (Contd.)
Bicycle - By attributing state and providing methods for changing that state, the object remains in control of how the outside world is allowed to use it. For example, if the bicycle only has 6 gears, a method to change gears could reject any value that is less than 1 or greater than 6.
Benefits of building code into individual software objects
Modularity
Information-hiding
Code re-use
Plug-ability and debugging ease 9

10. What is a Class?
A class is a blueprint or prototype from which objects are created
A class defines the general nature of a collection of objects of the same type
The process creating an object from a class is called instantiation
Every object is an instance of a particular class.
There can be many instances of objects from the same class possible with different values for data 10

11. Example
objects
Object
References
redRose
class Rose
blueRose
class 11

12. What is Inheritance?
Different kinds of objects have a certain amount in common with each other
For example mountain bikes, road bikes, and tandem Bikes all share the characteristics of bicycles (current speed, current pedal cadence, current gear)
Yet each also defines additional features that make them different: tandem bicycles have two seats and two sets of handlebars; road bikes have drop handlebars etc
Object-oriented programming allows classes to inherit commonly used state and behaviour from other classes 12

13. What is Inheritance? 13

14. What is a Interface?
Objects define their interaction with the outside world through the methods that they expose
Methods form the object's interface with the outside world
The buttons on the front of your television set, for example, are the interface between you and the electrical wiring on the other side of its plastic casing. You press the "power" button to turn the television on and off 14

15. Questions Real-world objects contain _____ and ________
A software object's state is stored in its _____
A software object's behaviour is exposed through _______
Hiding internal data from the outside world, and accessing it only through publicly exposed methods is known as data ___________
A blueprint for a software object is called a ____
Common behaviour can be defined in a _________ and inherited into a _______
state
behaviour
fields
methods
encapsulation
class
sub-class
super-class 15

16. THANK YOU
The material presented in these slides is used only for academic purpose
Copyright © Oracle Sun Microsystems 16