1. Course Summary Fall 2006 CS 101 Aaron Bloomfield

2. Course Reflection

3. Course goals Objectives: Students who complete the course will:
Understand fundamentals of programming such as variables, conditional and iterative execution, methods, etc.
Understand fundamentals of object-oriented programming in Java, including defining classes, invoking methods, using class libraries, etc.
Be aware of the important topics and principles of software development.
Have the ability to write a computer program to solve specified problems.
Be able to use the Java SDK environment to create, debug and run simple Java programs.

4. Unstated course goals
Everybody needs to have a “base” level of programming to continue on in the CS courses (or as required by other departments)
CS 101 and 201 provide that “base” level

5. What was new this semester
Each of the homeworks and exams are always new each semester
Because of the ‘fraternity file’ effect
The course project
A new one was developed for this semester
And it was handled better than it was last semester
The visual diagrams to show what was going on
Videos of lectures
Clicker response system
Using cs101 for faster response

6. Changes on deck for next semester
Will keep (and improve upon) all the stuff from the last slide
Study groups
The idea is a way for people to study and/or work together (not group assignments)
This is a bit difficult to implement unless you have very large lectures
Textbook is changing!
This will also mean the slides will change as well
Different clickers (the ones you use for CHEM 151)
Won’t be using CodeLab
Might use a similar system
I want to talk about debugging more
We are considering a site license for the debugging version of JCreator
Will (hopefully) have more TAs, and thus more TA office hours
Might have forums/newsgroups on the website

7. What didn’t work this semester
Textbook issues during the first month of the semester
One of the big reasons I’m changing books
Clickers!
Want to lower the amount of student frustration

8. What did work this semester
Videos of lectures
Clickers, sort of
Using cs101 for faster response
Many things that were “behind the scenes”
TA organization and utilization
Grading system
Me delegating the work better to the TAs
The marshmallow gun!

9. Did I push too hard this semester?
I pushed the class hard this semester
But did I push too hard?
Consider:
I’ve gotten more “things are going great” comments than I have “things are too hard” comments (anecdotal)
Homeworks took about 6 hours, on average
The results from the survey questions for each HW
There were 9 HWs over about 16 weeks
That’s about 3.5 hours (on average) on homeworks per week
From lab 12, This course required 5.2 hours per week outside of lectures
Other courses required 6.2 hours
I’m interested in your feedback on this!
But not today in lecture…
Please send (anonymous or not) if you have comments…

10. The Big OOP Picture

11. The classes for the game
Ship (HW J6)
Cell (HW J6)
Descriptions (lab 9)
ShipList (HW J7)
Parser (Lab 10)
AI (HW J8)
Human (provided in HW J8)
MapPrinter (lab 11)
Board (HW J9)
Game (provided)

12. How a big OOP program interacts
Note how the classes interacted in the game
A lot of objects were created and manipulated
A Cell for each spot in the Board grid
Ships possible in each Cell
Etc.
The way this game has objects interacting is how a big OOP program would work

13. Cell Ship Cell Ship Cell Cell Cell Cell Cell Cell “rowboat" ShipList b
isHit = false
+ …
Cell
length = 2
name
int xPosition = 0
int yPosition = 0
int hits = 1
boolean isH = false
+ …
Ship
ShipList
- int shipCount = 0
- Ship[] list
+ … b
ship
isHit = true
+ …
Cell
Board
- int NOT_SHOT_AT = 0
- int MISSED = 1
- …
- int sizex = 8
- int sizey = 8
- ShipList ships
- Cell [][] cells
+ …
(0,0)
length = 3
name
int xPosition = 4
int yPosition = 7
int hits = 1
boolean isH = true
+ …
Ship
ship
isHit = false
+ …
Cell
(7,7)
ship
isHit = true
+ …
Cell
ship
isHit = false
+ …
Cell
ship
isHit = true
+ …
Cell
ship
isHit = false
+ …
Cell
ship
isHit = false
+ …
Cell
“canoe"

14. Problem solving
To solve a problem in CS, you break it down into smaller and smaller pieces…
A big program is broken down into packages
Which we haven’t really seen yet
Consider the game to be one package
The packages are broken down into hierarchies
This uses inheritance
Our game didn’t use a hierarchy, as you did not know of inheritance at that point
The hierarchies are broken down into classes
The game had 10 classes
Each class is broken down into methods and variables
Some (such as MapPrinter) only had a few; others (such as Ship) had lots
Each method is broken down into parts, etc.

15. The completed game This could easily be made by multiple people
Each person does a separate class
Not exactly equal, but it still lowers the workload
Our (fully commented) code for the game was well over 1,000 lines
Granted, we had very long comments
However long yours was, it was a about a 1,000 line program
Even if you had trouble getting parts working, and had to use our code
You still wrote all the parts, and saw how they interacted with the rest of the system

16. Review of Chapter 1

17. Demotivator winners! Methodology
1st place vote counted for 3 points
2nd place vote counted for 2 points
3rd place vote counted for 1 point
Will buy two demotivators and hang them in my office…
The results were as of 11:00 today
The results, with 186 of 198 precincts reporting…

18. Engineering software
Complexity of software grows as attempts are made to make it easier to use
Several factors account for the increased complexity. First, to do more, the software is larger. It is not unusual for application programs, such as spreadsheets, word processors, and drawing programs, to consist of millions of lines of code. Another factor that increases complexity is the interaction between components. For example, a word processor may contain one component for spell checking and correction, and another component that provides the services of a thesaurus.
Let’s consider the spell-checking component. When a possible spelling error is detected, the spelling checker must report the possible error to the user. Thus the spelling checker must interact with the component of the application that creates a window or a dialog box so that the possible error can be displayed and the user queried about what action, if any, to take. If the user agrees it is a spelling error, the checker can correct the misspelling. To make the correction, the checker must interact with the component of the word processor responsible for replacing text in the document. Obviously, as the number of components grows, the number of interactions between components can grow rapidly.

19. Software engineering Goal
Production of software that is effective and reliable, understandable, cost effective, adaptable, and reusable
Design software so that new features and capabilities can be added
Goal
Production of software that is effective and reliable, understandable, cost effective, adaptable, and reusable
Makes sense due to the great costs involved to have flexible components that can be used in other software
Goal
Production of software that is effective and reliable, understandable, cost effective, adaptable, and reusable
Cost to develop and maintain should not exceed expected benefit
Goal
Production of software that is effective and reliable, understandable, cost effective, adaptable, and reusable
Because of the long lifetime many people will be involved
Creation
Debugging
Maintenance
Enhancement
Two-thirds of the cost is typically beyond creation
Goal
Production of software that is effective and reliable, understandable, cost effective, adaptable, and reusable
Goal
Production of software that is effective and reliable, understandable, cost effective, adaptable, and reusable
Work correctly and not fail

20. Principles of software engineering
Abstraction
Encapsulation
Modularity
Hierarchy
Abstraction
Encapsulation
Modularity
Hierarchy
Abstraction
Encapsulation
Modularity
Hierarchy
Abstraction
Encapsulation
Modularity
Hierarchy
Abstraction
Encapsulation
Modularity
Hierarchy
Determine the relevant properties and features while ignoring nonessential details
Ranking or ordering of objects
Construct a system from
components and packages
Separate components into external and internal aspects

21. Object-oriented design
Purpose
Promote thinking about software in a way that models the way we think and interact with the physical word
Including specialization
Object
Properties or attributes
Behaviors
Now let’s analyze this activity. First, you recognized the need for action—having to get up early and deciding that the clock radio could help meet that need. So you go over to the clock radio, which is a physical object. This object has properties like weight and size, and it also can do something. For one it can play music at an indicated time. It’s not necessary for you to know entirely how the clock radio works. You need to know only which switches and buttons to use. The switches and buttons are the interface to the clock radio. If you understand the interface to an object, you can use it to perform some tasks without understanding how the object works internally. Moving the appropriate switches and pushing the appropriate buttons are signals to the clock radio to modify its behavior.
Such interactions are so routine that it is easy to overlook how amazing this activity is. You were able to make an object perform a complex activity without understanding the internal operation of the object. You were able to do so because you had an appropriate abstraction of the object. Indeed your mental abstraction of a clock radio means that when you travel and stay at a hotel room, you are able to set its clock radio even though it is a different clark radio. Similar objects often exhibit similar behavior.
This way of dealing with the complex world around us also can be applied to software design and programming. A key step in developing a complex system using object-oriented design is to determine the objects that constitute the system. By carefully creating appropriate abstractions of these objects and separating their internal implementation from their external behavior, we can manage the complexity of a large software system.
So what exactly do we mean by an object? Physical things are certainly objects. A ball, a file cabinet, an address book, a tree, and a computer all are objects. What about things like a word, a bank account, or a musical note? These things are not physical objects, but they are objects—in the sense that they have attributes and properties, and we can perform actions on them. A word has a length and meaning, and if we are talking in regard to a word processor, a word can be inserted or deleted from a document. A bank account has a balance to which funds can be deposited or debited. A musical note has pitch, duration, and loudness and can be played. For the most part, something is an object if it has a name, properties associated with it, and behaviors such as message handling.
Typically, when an object receives a message, the message causes the object either to take some action or to change one of its properties. Continuing with our clock radio example, when you push the “music on” button, the current broadcast is played.
If we are going to take an object-oriented approach to developing software, it makes sense to use a programming language such as Java that supports thinking and implementing solutions in terms of objects. A language with features that support thinking about and implementing solutions in terms of objects is an object-oriented programming language.
Using an object-oriented programming language to implement an object-oriented design is called object-oriented programming. Notice we were very careful to include the phrase “implement an object-oriented design.” As you will see later, you can use an object-oriented language, but not think in terms of objects.

22. Programming Problem solving through the use of a computer system Maxim
You cannot make a computer do something if you do not know how to do it yourself

23. Problem Solving Process
What is it?
Analysis
Design
Implementation
Testing

24. Problem Solving Process
What is it?
Analysis
Design
Implementation
Testing
Determine the inputs, outputs, and other components of the problem
Description should be sufficiently specific to allow you to solve the problem

25. Problem Solving Process
What is it?
Analysis
Design
Implementation
Testing
Describe the components and associated processes for solving the problem
Straightforward and flexible
Method – process
Object – component and associated methods

26. Problem Solving Process
What is it?
Analysis
Design
Implementation
Testing
Develop solutions for the components and use those components to produce an overall solution
Straightforward and flexible

27. Problem Solving Process
What is it?
Analysis
Design
Implementation
Testing
Test the components individually and collectively

28. Problem Solving Process

29. Tips Find out as much as you can Reuse what has been done before
Expect future reuse
Break complex problems into subproblems

30. Tips Find out as much as you can Reuse what has been done before
Expect future reuse
Break complex problems into subproblems
Consider
Sketching a solution and then repeatedly refine its components until the entire process is specified
Find out what is known about the problem
Talk to the presenter
Determine what attempts have succeeded and what attempts have failed
Research can require significant time and generate questions
The effort is worthwhile because the result is a better understanding
True understanding of the problem makes it easier to solve

31. Tips Find out as much as you can Reuse what has been done before
Expect future reuse
Break complex problems into subproblems
Be open to indirect use of existing materials
Your time is valuable
Correctness is probably even more valuable
Use existing infrastructure that is known to work

32. Tips Find out as much as you can Reuse what has been done before
Expect future reuse
Break complex problems into subproblems
Make as few assumptions as necessary
Maximizes the likelihood that your effort can be used in future situations

33. Tips Find out as much as you can Reuse what has been done before
Expect future reuse
Break complex problems into subproblems
Divide-and-conquer
Solve subproblems and combine into an overall solution

34. And the winner, with 37 votes, is…

35. Have a great holiday break!