1. CS 200 Additional Topics and Review
Jim Williams, PhD

2. Week 14 Piazza: New CS Declaration Req. @1142 BP2
Team Lab: Object-Oriented Space Game
TA Evaluation
Hours Last Week & CS 300
Course Evaluation ( ed link)
Lecture: UML, Additional Topics

3. Recent Course Improvements
Redesign of Intro Course (CS302 -> CS200) Study Cycle Problem Solving Tips
Team Labs as study groups
emphasize reading Java, unexpected behavior
Projects
emphasize incremental development & testing
Increased assistants and office hours

4. Changes Possible
Computer Science is influencing every field, including education.
This potential seems exciting but not clear in what ways education will be positively influenced.

5. Brainstorm on Improving Course

6. Course Survey
Lecture, Homework, Projects, Materials, Feedback
Instructor: Overall, Responsiveness, Environment
Recommend Course
Growth Questions (e.g., bring laptop to Team Lab).
What would you expect in order to rate course in the top rating (7) of each category? Or why didn't you give a top rating?
Please! describe in the open ended notes.

7. Course Evaluations

8. Lots of Jobs if you understand Programming
Software Developer/Programmer/Software Engineer
Testing/Quality Assurance
Technical Support
Technical Writing
Business/Systems Analyst
Software Architect
Product Manager
Project Manager
Development Manager
Technical Sales
Marketing

9. Analysis and Design Analysis: Describing the Problem
Design: Describing a Solution

10. UML Diagrams UML (Unified Modeling Language)
Many diagrams with lots of details
Goal in CS 200 is to recognize:
Use Case Diagram
Class Diagram
Object Diagram
Activity Diagram/Control Flow

11. UML Diagrams: References
Examples of Diagrams:
Simple Drawing Tool:

12. Use Case Behavior diagram
How external users (actors) interact with the system.

13. Class Diagram
Shows structure of a system with features, constraints and relationships.
Independent of time.

14. Object Diagram A snapshot of a system at a point in time.
Instances of classes with specific attribute values.

15. Activity Diagram (Control Flow)
Behavior diagram
Shows flow of control emphasizing sequence and conditions

17. What Kind of Diagram is this?
Use Case Diagram
Class Diagram
Object Diagram
Activity Diagram/Control Flow

18. What Kind of Diagram is this?
Use Case Diagram
Class Diagram
Object Diagram
Activity Diagram/Control Flow

19. What Kind of Diagram is this?
Use Case Diagram
Class Diagram
Object Diagram
Activity Diagram/Control Flow

20. What Kind of Diagram is this?
Use Case Diagram
Class Diagram
Object Diagram
Activity Diagram/Control Flow

21. Problem
With a command line program show the files in all subfolders of a folder.

22. Recursive Algorithm
Repeated applications of an algorithm on smaller versions of the same problem.
Eventually reach a base case which is simply solved.

23. Recursion Example public class Show {
public static void show(File file, String depth) {
System.out.printf("%s%s\n", depth, file.getName());
if ( file.isDirectory()) {
File[] files = file.listFiles();
for (int i = 0; i < files.length; i++) {
show(files[i], depth + " "); }
public static void main(String[] args) {
File file = new File(".");
show(file, " ");
import java.io.File;
public class Show {
public static void show(File file, String depth) {
System.out.printf("%s%s\n", depth, file.getName());
if ( file.isDirectory()) {
File[] files = file.listFiles();
for (int i = 0; i < files.length; i++) {
show(files[i], depth + " "); }
public static void main(String[] args) {
File file = new File(".");
show(file, " ");

24. Recall Fibonacci Sequence…
First 2: 1, (base case)
Others: sum of previous 2 (recursive step)
Example: If we want to find the 5th number:
5th = 4th + 3rd

25. Recursive Solution Base case: Can be simply solved Recursive step:
Break into smaller problems
static int fib(int num) {
if ( num <= 1) return 1; //base case
else return fib( num -1) + fib( num -2); }
public static void main(String[] args) {
System.out.println("fibonacci 4: " + fib(4));

26. Iterative solution public static void main(String[] args) {
int n = 10;
int [] fib = new int[n];
fib[0] = 1;
fib[1] = 1;
for (int i = 2; i < n; i++) {
fib[i] = fib[i-1] + fib[i-2]; }
System.out.println("fib "+n+"= " + fib[n-1]);

27. Iteration vs Recursion
Each may be better (simpler, clearer, more efficient) for a problem.
Some problems, such as navigating trees, recursion is frequently a helpful and elegant solution.

28. How does recursion end?
base case that simply solves the problem.

29. Course Review
Key Principles, Tools, Diagrams, Data Types, Operators, Keywords, Control Flow, Programming Paradigms, Debugging Techniques, File Input/Output, Commenting & Style, Unit Testing, Memory, Best Practices, Learning Programming

30. Key Principles
Algorithms
Abstraction

31. Tools
zyBooks, JavaVisualizer, DiffChecker, Command Prompt, notepad, javac, java, Eclipse IDE (editor, compiler, vm, debugger)

32. Diagrams
truth tables, memory model diagrams, control flow charts (activity diagrams), class diagrams, object diagrams, and use-case diagrams.

33. Data Types Primitive & Reference Primitive: 8
Reference: existing, classes you write.

34. Operators

35. Evaluating Java Expressions
Precedence
Associativity
Sub-expressions left-to-right

36. Control Flow
Sequence
Methods
Conditionals
Loops

37. Data Structures Arrays: single and multi-dimensional ArrayLists
ArrayLists of Arrays

38. Development Process Edit-Compile-Run cycle
Analysis - understand the problem
Design - pseudocode

39. Best Practices Incremental, systematic, frequent deliverables
Test frequently
Test bench with testing methods
Add additional tests as requirements are determined or bugs are found.

40. Debugging Techniques Stepping through code Problem decomposition Tips
Java Visualizer
Eclipse debugger
Problem decomposition
Print statements, debugger
Tips

41. Programming Paradigms
Structured Programming
Object-Oriented Programming (brief)

42. Applied Study Cycle
frequent, varied interactions with material

43. zyBooks Participation Activities
Assigned readings with small activities due before lecture

44. Lecture - Activities Definitions & Explanations Drawing Diagrams
Demonstration
Stories
Retrieval Practice
Questions, including TopHat

45. zyBooks Challenge Activities
Application of previous week's material to small programs.

46. Team Lab Weekly paired and small group study with mentor nearby.
Required interaction with mentor on key topics.
Variety of activities to learn Terms, Read, Write, Test & Debug code.

47. Weekly Programs
Application of programming concepts to design algorithms and write code to solve problems.
Small programs early, large programs with milestones later.
Incrementally developing skills on larger and more complex programs.

48. Exams
Assess careful reading and tracing skills.

49. Memory areas
static: holds static variables when class is loaded into memory.
heap: where instances/objects are allocated
stack: where local variables and parameters are allocated each time a method is called.

50. Memory public class M { int varName = 1; static int cVar = 2;
public M(int varName ) {
this.varName = varName; }
public static void main(String []args) {
M[] varName = new M[3];
varName[0] = new M(3);
varName[1] = new M(4);

51. How many Bug instances in list?2
2 copies of reference to 1 bug
none, error, no list 3
ArrayList<Bug> list;
list = new ArrayList<Bug>();
list.add( new Bug());
Bug aBug = new Bug();
list.add( aBug);
list.add( 0, aBug);
import java.util.ArrayList;
class Bug {
private static int count = 0;
private final int id;
Bug() {
id = ++count; }
public String toString() {
return "Bug:" + id;
public class ClassNameHere {
public static void main(String[] args) {
ArrayList<Bug> list = new ArrayList<>();
list.add( new Bug());
Bug aBug = new Bug();
list.add( aBug);
list.add( 0, aBug);
System.out.println( list);

52. Exceptions new Exception() //records the stack trace
throw //starts live exception handling
throws //method may throw an exception
try-catch //stops live exception handling
finally //code to always execute

53. Exception Handling 3 Categories Error - internal system errors
Unchecked Exceptions
RuntimeException
Checked Exceptions
Exception

54. Programming Process & Errors
Naming/Saving
Syntax/Compile time
Runtime & Logic
Users
Editor
(Virtual)
Machine
Compiler
Hello.java
Hello.class
Computer
Files
Programmer

55. Classes
Class vs Instance Members (from docs)
Creating your own

56. CS 300 Suggestion
Setup your own weekly study group reviewing & discussing previous weeks material.

57. Good Luck on Exam!
Have a Great Summer!

58. Which is false? every instance will have the exact same toppings
toppings is a class variable
can be accessed by any method
cannot be changed
class Pizza {
static String toppings; }
A, B & C are true
D is false since toppings would have to be 'final' to not be changed.

59. toppings is a(n) instance (non-static) variable class Pizza {
private String toppings;
public String getToppings() {
if ( toppings == null)
toppings = "no toppings";
return toppings; }
instance (non-static) variable
class (static) variable
parameter
local variable
A is true,
B, C and D are false

60. getToppings() is a(n) method getter class Pizza {
private String toppings;
public String getToppings() {
if ( toppings == null)
toppings = "no toppings";
return toppings; }
method
getter
accessor
provides read-only access to toppings field
All of the above
All are true.

61. The visibility modifier private is
appropriate
should be public
doesn't allow a user of this class to change the field (attribute) directly
allows only methods within this class to change the field.
class Pizza {
private String toppings;
public String getToppings() {
if ( toppings == null)
toppings = "no toppings";
return toppings; }
A, C & D are true
B is false

62. Which is false? is a class method class Pizza {
can change toppings (write access)
is a setter
is a mutator
class Pizza {
private String toppings;
public void setToppings( String tops) {
if ( tops != null && tops.length() > 0)
toppings = tops; }
B, C and D are all true.
A is false as setToppings does not have the 'static' keyword in the header before void.

63. Does this print true or false?
class Person {
private boolean something = false;
boolean getThing(boolean something) {
return this.something; }
public static void main(String []args) {
Person p = new Person();
System.out.println( p.getThing( true));
true
false
error/other
try it and see.

64. Which is true? class Light { } // in some method
error - no constructor
Object classes' toString() will be called
an instance of Light has nothing in it
error
class Light { }
// in some method
Light aLight = new Light();
System.out.println( aLight);
A: false, since there is no constructor the default, no-arg constructor is provided by the compiler
best answer: B: Object classes' toString() will be called
C: false, since Light implicitly extends from Object and therefore when instantiated has all the instance fields of class Object within it.
D: no error noted, although code isn't complete as shown, but with reasonable assumptions should run.

65. What will print out? 1 can't access a private field outside the class1
can't access a private field outside the class
error
class Employee {
private static int employeeCount = 0;
private final int id;
Employee() {
this.id = ++employeeCount; }
public static void main(String []args) {
Employee anEmployee = new Employee();
System.out.println( anEmployee.id);
try it and see

66. Does this print 0, 1, other or error?
public class Person {
static int count = 0;
private int id;
Person() {
this.id = ++count; }
public static void main(String []args) {
System.out.println( Person.count); 1
other
error
try it and see

67. What will print out? 1 can't access a private field outside the class1
can't access a private field outside the class
error
class Employee {
private static int employeeCount = 0;
private final int id;
Employee() {
this.id = employeeCount++; }
public static void main(String []args) {
Employee anEmployee = new Employee();
System.out.println( anEmployee.id);
try it and see

68. Bike Design a bike class. Instance Fields: numWheels, Color, unique id
Class Field: numBikesCreated, used to assign unique id’s to each bike.
Constructor: numWheels and Color, automatically sets the unique identifier.
Instance Methods: Number of Wheels and id can be accessed but not changed. Color can be changed. Add a toString() method to return all instance field values in String form.
Class Method: returns the number of bikes created.
Draw the UML diagram and then write the code.
Create a BikeShop class that creates 10 bikes and stores in an array.
Print out each bike’s number of wheels, color and id using the toString method.
Can you write the code and draw the diagram?