1. Unified Modeling Language (UML)
AP Java
Unified Modeling Language (UML)

2. Be able to model a single class using Unified Modeling Language (UML)
Learning Objectives
Be able to model a single class using Unified Modeling Language (UML)
Use a UML diagram to help create a class.

3. Big questions What is UML? What is a UML class diagram?
Why should I bother? Do people really use UML?
What is a UML class diagram?
What kind of information goes into it?
How do I create it?
When should I create it?

4. Design phase
design: specifying the structure of how a software system will be written and function, without actually writing the complete implementation
a transition from "what" the system must do, to "how" the system will do it
What classes will we need to implement a system that meets our requirements?
What fields and methods will each class have?
How will the classes interact with each other?

5. How do we design classes?
class identification from project spec / requirements
nouns are potential classes, objects, fields
verbs are potential methods or responsibilities of a class
UML diagrams
class diagrams (today)
sequence diagrams
...

6. Introduction to UML UML: pictures of an Object Oriented (OO) system
programming languages are not abstract enough for OO design
UML is an open standard; lots of companies use it
What is legal UML?
a descriptive language: rigid formal syntax (like programming)
a prescriptive language: shaped by usage and convention
it's okay to omit things from UML diagrams if they aren't needed by team/supervisor/instructor

7. Uses for UML as a sketch: to communicate aspects of system
forward design: doing UML before coding
backward design: doing UML after coding as documentation
often done on whiteboard or paper
used to get rough selective ideas
as a blueprint: a complete design to be implemented
sometimes done with CASE (Computer-Aided Software Engineering) tools
as a programming language: with the right tools, code can be auto-generated and executed from UML
only good if this is faster than coding in a "real" language

8. UML class diagrams What is a UML class diagram?
UML class diagram: a picture of the classes in an OO system, their fields and methods, and connections between the classes that interact or inherit from each other
What are some things that are not represented in a UML class diagram?
details of how the classes interact with each other
algorithmic details; how a particular behavior is implemented

9. Diagram of one class class name in top of box
attributes (Instance Variables)
should include all fields of the object
operations / methods
may omit trivial (get/set) methods
but don't omit any methods from an interface!
should not include inherited methods

10. Class attributes/Variables
attributes (fields, instance variables)
visibility name : type [count] = default_value
visibility: + public (all) # protected (family) - private (me) ~ package (default/Folder) / derived
underline static attributes/class variables
derived attribute: not stored, but can be computed from other attribute values
attribute example: - balance : double = 0.00

11. Class operations / methods
visibility name (parameters) : return_type
visibility: + public # protected - private ~ package (default)
underline static methods
parameter types listed as (name: type)
omit return_type on constructors and when return type is void
method example: + distance(p1: Point, p2: Point): double

12. Practice: In your notes… Create a UML Diagram for a Fraction class
Default Constructor
Constructor given integer numerator/denominator
Multiply by a Fraction object and return the product as a Fraction object
Add to a Fraction object and return the sum as a Fraction object.
toString. Return a String representation of the object.

13. Using the UML To Help with a Free Response Question
In the next section you will create a UML Diagram for the Quiz Question
Then we will go over creating the class as a class.
Read over the Question and Create a UML diagram for the TextFormatter class.

14. Part A private int findString(String str,int start)
Hands On:
line = “aabaccb”
Pseudo Code
Find first occurrence of str in line (position).
While there is an occurrence of str in line
If it is a single occurrence (not a duplicate)
Return this position
Else //If it matches the letter before and/or after
Find the next occurrence of str in line
Return -1 (No single occurrences)
Checking for Single Occurrence
If it is the first letter (position = 0)
check to make sure it does not match the next letter.
Else If it is the last letter (position =line.length() -1)
Check to make sure it does not match the previous letter.
Else
Check to make sure it does not match the previous or next letter
TextFormatter
- line : String
+ TestFormatter(lineToFormat:String)
findString( str: String, start:int):int
countStrings(str:String): int

15. Problem A More Refined Pseudo Code
Find first occurrence of str in line (position).
While there is an occurrence of str in line
If it is the first letter (position = 0)
if it does not match the next letter.
Return this position
Else If it is the last letter (position =line.length() -1)
If it does not match the previous letter.
Else //if it is not the first or last position in line
If it does not match the previous or next letter
Else //If it matches the letter before and/or after
Find the next occurrence of str in line
Return -1 (No single occurrences)

16. Modify the following Driver Class for Testing

17. Part b: countStrings
This method will be sent a single character string (str) and will count the number of times single instances of the goal string appears in the String line.

18. Part b Pseudo Code Start a position 0 and count 0
While there is str in line from position
Add to the count
add one to position
Return the count

19. Part c: convertItalics()
If there are an even number of “_” then for each pair of “_” replace
“<I>” marking the beginning of a section of “_”
“</I>” marking the end of a section
Returning the converted String

20. Pseudo Code If there are an odd number of “_” then
Return the original ‘line’
Make a temporary String (answer) to add the modified String
Make front and back variables for copying the parts of line into answer String
For each pair of “_”
Replace the first “_” with “<I>”
Set back to findString(“_”, front)
Add string from front to back and “<I>” to answer
Set front to back + 1
Replace the second with “</I>”
Add string from front to back and “</I>” to answer
Add the rest of the String to the answer
Return answer

21. Assignment
Complete the TextFormatter class and driver class to test it.