Question 1 of MCS-219: Object Oriented Analysis and Design.
OOAD (Object-Oriented Analysis and Design) is a software engineering approach that focuses on modeling a system as a collection of interacting objects. These objects represent real-world entities and combine data (attributes) with behavior (methods).
OOAD helps in understanding system requirements (analysis) and translating them into a robust, reusable, and maintainable software design (design).
Basic Constructs of Object Orientation
1. Object
An object is a real-world entity that has:
- State (data/attributes)
- Behavior (functions/methods)
- Identity (uniqueness)
Example:
A Student object with attributes like rollNo, name, and methods like register().
2. Class
A class is a blueprint or template used to create objects. It defines:
- Attributes (data members)
- Methods (member functions)
Example:class Student { rollNo, name, register() }
3. Encapsulation
Encapsulation is the mechanism of wrapping data and methods together into a single unit (class) and restricting direct access to some data.
Benefit: Data security and controlled access.
4. Abstraction
Abstraction means showing only essential features and hiding internal implementation details.
Example:
Using an ATM without knowing its internal processing logic.
5. Inheritance
Inheritance allows a class to acquire properties and behavior of another class.
Example:Teacher and Student classes inheriting from a Person class.
Benefit: Code reusability.
6. Polymorphism
Polymorphism means one interface, many implementations. A single function or method behaves differently based on the object.
Example:print() method working differently for Student and Teacher.
7. Message Passing
Objects communicate with each other by sending messages (method calls).
Example:student.getResult() calls a method of the student object.
8. Dynamic Binding
The method to be executed is decided at runtime, not at compile time.
Example:
Method overriding in inheritance.
Conclusion
OOAD helps in building modular, scalable, and maintainable software systems by using object-oriented principles such as encapsulation, inheritance, abstraction, and polymorphism.