1. CSCI 130
Classes and Objects

2. Classes
Templates from which programmatic building blocks are constructed
Model physical entities
Have the ability to ‘construct’ instances of the templates
Class contains:
Attributes
Behaviors

3. Example
Write up the attributes and behaviors of a Car class

4. Objects Actual instance of a class
In an object-oriented program objects interact with each other
Objects may be constructed from other objects
Black box concept
Other objects don’t care how an object performs its tasks, only that it does perform them

5. Important OOP concepts
The instances of each class have complete control over the accessibility of their attributes and behaviors as defined by the class
Classes can be related in a hierarchical fashion from general to specific
Some instances of classes have the ability to morph themselves into other (related) classes

6. Example
Create a class hierarchy for all vehicle objects

7. Identifying Classes Done in design phase Most difficult part of OOP
define, design, code, test, document
Most difficult part of OOP
must view entire system in OO terms
good initial design leads to highly effective programming
bad initial design leads to wasted time and effort