1. SOEN 343 Software Design
Computer Science and Software Engineering Department
Concordia University
Fall 2004
Instructor: Patrice Chalin

2. Reminders
Hand in your solutions to Exercise Set 1 (they will be returned).
Homework is given in this lecture (see last slide).
4/7/2019
SOEN 343, © P.Chalin,

3. Agenda – Lecture 2a OO fundamentals continued. Design
Delegation, polymorphism.
Design
“Levels”
Methods
UML flash: a language for expressing designs.
Test Drive Development (TDD) and refactoring – a first demonstration – skipped, ran out of time due to room change delay.
4/7/2019
SOEN 343, © P.Chalin,

4. Java – some details to be read on your own.
Primitive types: include
Floating point : float, double.
Integral : byte,short,int,long,char.
boolean, is not assignment compatible with integral types; explicit conversion required.
boolean b = (i == 0 ? false : true);
Class types for “boxing”:
Float, Double, Byte, … Boolean.
E.g. Boolean o = new Boolean(b);
4/7/2019
SOEN 343, © P.Chalin,

5. java.util.Vector Vector class Example of use
Implements a growable array of objects.
Example of use
String s = …;
Vector v = new Vector();
v.add(s); // adds to end
String t = v.elementAt(0);
v.remove(s);
int i = v.size();
List interface
ArrayList class
4/7/2019
SOEN 343, © P.Chalin,

6. OO Fundamentals (Exercise Set 2)
Answer Q1 and Q2 of Exercise Set 2
Delegation.
Polymorphism.
4/7/2019
SOEN 343, © P.Chalin,

7. Design vs. Requirements and Implementation.
Architectural
Detailed
4/7/2019
SOEN 343, © P.Chalin,

8. Design Levels Architectural design Detailed design.
Detailed design
Implementation (executable designs)
4/7/2019
SOEN 343, © P.Chalin,

9. Two complimentary approaches to design
Planned Design vs. Evolutionary Design
Can we get away with only planned design?
4/7/2019
SOEN 343, © P.Chalin,

10. Evolutionary Design Practices Important characteristicsXP
Test driven development (TDD)
Do not add code unless you have a test failing …
Important characteristics
“Full” automated test suites
Refactoring
Help us learn detailed design idioms, patterns, …
4/7/2019
SOEN 343, © P.Chalin,

11. Refactoring
A refactoring is a change made to the internal structure of S/W to make it easier to understand and less expensive to modify, without changing its observable behavior.
4/7/2019
SOEN 343, © P.Chalin,

12. Can you pick out a good design?
What is a good design?
Satisfies user needs.
Is a simple as possible. Kent Beck:
Runs all tests
Reveals intention.
No duplication.
Fewest number of classes or methods
… can you smell bad design choices?
4/7/2019
SOEN 343, © P.Chalin,

13. “Bad Smells” Duplication. Long method. … we will be learning more.
4/7/2019
SOEN 343, © P.Chalin,

14. Further Reading Martin Fowler’s, “Is Design Dead”?
martinfowler.com/articles/designDead.html
4/7/2019
SOEN 343, © P.Chalin,

15. UML Class Diagram – Class
Parts named in class
4/7/2019
SOEN 343, © P.Chalin,

16. UML Class Diagram Generalization (inheritance) Dependency
4/7/2019
SOEN 343, © P.Chalin,

17. [Homework] Exercise Set 2
Complete the exercise set 2.
4/7/2019
SOEN 343, © P.Chalin,