1. Object Oriented Concepts

2. Object Orientation
An Object oriented approach views systems and programs as a collection of interacting objects.
An object is a thing in a computer system that is capable of responding to messages

3. The Idea of OOP
The idea of OOP is to try to approach programming in a more natural way by grouping all the code that belongs to a particular object—such as a checking account or a customer—together

4. Objects Core to the idea of OOPs is the concept of an object.
An object is anything that is relevant to your program
A customer, an employee, Inventory, a database, a button, a form, a sale are all potential objects

5. Benefits of Objects
More natural way to look at things
Re-usability

6. Objects/Classes A class is a description of an object.
This description can include attributes which describe the class
It can also include “methods” which describe things the object can do.
In programming an object is an actual instance of a class

7. Messages Object communicate among themselves by means of messages
The also maintain “associative relationships” among themselves

8. A Class Diagram

9. Principles of OOP
Abstraction
Encapsulation
Inheritance
Polymorphism

10. Abstraction
The idea of abstraction is that a class represents an “abstract” version of an object
A customer class presents the abstract idea of what a customer is
A sale class represents an abstract idea of what a sale is

11. Encapsulation
Encapsulation refers to the idea that a class should contain all the properties and methods of an object
It also means you should be able to use the object without knowing the details of how it is structured internally

12. Inheritance
Inheritance means you can derive a new object from an existing one
It also means that the new object will have access to (will inherit) the properties and methods from the parent object

13. Inheritance
Generalization/ Specialization

14. Polymorphism
Polymorphism means that objects descended from a particular types will behave appropriately
For example (a listbox and a button are both descended from the same class called control—but they each will behave differently)
Polymorphism is primarily implemented through overriding and overloading functions and operators

15. Relations Classes relate to each other in various ways
We have already looked at inheritance
Classes can also have a “binary” relation, in which one class calls another
There is also a relation called composition in which one class is contained as a field in another class

16. Example of Composition