1. Introduction Object-Oriented Programming

2. The Journey So Far Procedural Programming using Pseudocode You are
here

3. The Destination Procedural Programming Object Oriented Programming
using Pseudocode
using Java

4. Introduction We are going to introduce two concepts at the same time:
Object-Oriented Programming
Programming in a real language
Why?
Pseudocode is a good preparation for learning any language.
The Object Oriented paradigm is a significant factor in modern programming
We feel that an introductory course should at a minimum give students a good taste of real programming
Many students have asked for exposure to a real language
Excellent preparation for CS 1312

5. Introduction
We will not abandon the principles you have learned so far:
modularity
abstraction
the necessity to visually validate the logic
Today we will give some basic ideas about:
Object Oriented Programming
Working with a real language: Java

6. Object Oriented Programming
A different programming style
A different way of thinking
Origins
Problems with very large systems becoming unmanageable (> 100,000 lines of code)
Graphical User Interfaces (e.g. Macintosh, Windows) required a different way of programming due to complex interactions of windows, mouse clicks, etc.
Xerox PARC: Smalltalk
C++ as an enhancement to C
Java as a Web language

7. To be more specific...

8. The Scenario Items Recall the concept of a Queue:
Defined by a set of behaviors
Enqueue to the end
Dequeue from the front
First in, first out
Items

9. Where is the Queue? The logical idea of the queue consisted of:
Data stored in some structure (list, array, etc.)
Modules to act on that data
But where is the queue?
We’d like some way of representing such a structure in our programs.

10. Why?
We would like to have reusable “drop-in” programming components we could use to solve problems.
We would like to encapsulate the data and the behaviors in order to “protect” it from misuse.
We would like clear interfaces between different parts of programs
We would like a programming system that was extensible
We would like a programming language that would be excellent for modeling real world objects

11. Issues
As is, there is no way to “protect” against violating the specified behaviors.
Procedure
Enqueue
Procedure
Dequeue
The Queue Data
Sneak into Middle

12. Issues
If our queue could somehow be packaged we could drop in a “queue object” whenever we needed it.
Queue
Acme Manufacturing

13. Issues
We’d like a way to put a “wrapper” around our structure to protect against intrusion.
Queue
Acme Manufacturing
Enqueue
Dequeue
Sneak into Middle

14. Issues
Contract
The party of the first part hereinafter known as the queue agrees to...
The party of the second part hereinafter known as the application agrees to...
Clear lines
of responsibility

15. Issues
I need a queue that can tell me how many items it contains...
Queue
Enqueue
Dequeue
Acme Manufacturing
“Magic Process”
CountingQueue
Acme Manufacturing
Enqueue
Dequeue
Size

16. $ Issues Signal Elevator Signal Object Elevator Object Student Student
Car
Object
Car $
BankAccount
BankAccount
Object
Real World Objects!