2. Objectives
Definition of Object Oriented, Object, Class and relationship
between Object and Class
General structure of a Class
How Objects are created and used
Characteristics of Object Oriented Programming
3. What is Object-Oriented Programming?
"Object oriented" means that we organize software as a
collection of discrete objects that have both data and structure
Example: to go From point A to point B
Non OO:
Drive(200 miles) (just do it)
OO:
myCar =new HondaAccord();
myCar.drive(200miles)
6. What is Object?
1) Object: eveything in the world is an object - concrete or
conceptual. It is an instance of a Class
2) Object
Can be real-world objects: this desk, this ballpen,etc
Can represent GUI (Graphical User Interface) components
Can represent software entities (events, files, images, etc.)
Can represent abstract concepts (for example, rules of a game, a
particular type of dance, etc.)
---Ask students: can anyone give an example of some Objects???
7. What is Class?
a factory or blueprint that define a similar type or group
of objects
example: HondaAccordCar, Boeing747Airplane
8. Relation between Object and Class
Object Class
has identity, a a blueprint or
unique instance of factory that holds
a Class or produce the
objects
dynamic, static structure
generated in written by
runtime programmers
9. a Class Example
import java.awt.color;
public class HondaAccord {
private Color carColor;
public HondaAccord(Color carColor){
this.carColor= carColor;
}
public void Drive(int miles){
...
}
}
10. Usage example
public class CarUsageExample{
public static void main(Strings args[]){
HondaAccord myBlueHonda=
new HondaAccord(Color.blue);
myBlueHonda.drive(200); //go 200 miles
}
}
11. Characteristics of OO Programming
Abstraction: focus on the essential characteristics of an
object that distinguish it from others, relative to the
perspective of the viewer
Encapsulation: detail or implementation hidden so that
only interface exposed
Polymorphism: same function name can have different
behavior depending on its subtype (airplane.travel() vs car.
travel())
Inheritance: is-a relationship
12. OO design principles
SRP- single responsibility (high cohesion): a class should have
one reason to change
OCP-open-close: class should be open to extension, close to
modification
LSP- Liskov substitution: subtype is-a basetype, therefore can
substitute for it.
DIP - dependency inversion: code to (depend to) interface (high
level modules should not depend on low level modules)
ISP-interface segregation principle: when there is incohesion,
separate them into different interfaces
-from Agile Software Development by Robert Martin
