1. Slide design: Dr. Mark L. Hornick
SE-2811
5/23/2018
Week 6, Day 2: Decorator
Review Muddiest Points for Quarter
Decorators
Muddiest Point
Tomorrow:
Direct Supply tour with Kent Newbury
Demos of (hopefully working) labs
Lab due in the evening
No new lab this week.
SE-2811
Slide design: Dr. Mark L. Hornick
Content: Dr. Hornick
Errors: Dr. Yoder
Dr. Yoder

2. SE-2811
5/23/2018
Muddiest Point
See Muddiest Point Table online: slides/se MuddiestPoint.xlsx (and on my machine)
SE-2811
Dr. Mark L. Hornick
Dr. Yoder

3. How are decorators useful?
CS-1020
5/23/2018
How are decorators useful?
Decorators have the same super-type as the objects they decorate.
One or more decorators can be used to wrap an object.
One answer to question 1: Given that the decorator has the same super-type as the object it decorates, we can pass around a decorated object in place of the original (wrapped) object.
One answer to question 2: Objects can be decorated at any time, so we can decorate objects at runtime with as many decorators as we like.
Helps organize: e.g., can put all beverage objects in the same data-structure
Used when initializing super-class
Why is this useful?
Can still get to specific & useful method
When creating the object
By casting back to cream (leaves open question: Is it cream?)
Test using instanceof
Can get more & more specific about the object with multiple decos.
Don’t need all the classes for all combinations
Dr. Mark L. Hornick

4. Downsides What are the disadvantages of decorators?
SE2811
5/23/2018
Downsides
What are the disadvantages of decorators?
See interview drama on p. 104 in the text (Head First)
Large number of small classes overwhelming to new developers
Problem when people rely on specific types without thinking through [TODO: Study & find example]
e.g. Consider the mess if the interface does not already exist for the class
Complexity of wrapping many to construct a new one
SE-2811
Dr. Mark L. Hornick
Dr. Josiah Yoder

5. Forced selection: Do you like Java's I/O? Yes / No
5/23/2018
Forced selection: Do you like Java's I/O? Yes / No
SE-2811
Dr. Mark L. Hornick
Dr. Yoder

6. Join those who agree with you in defending your position!
5/23/2018
Join those who agree with you in defending your position!
I like Java's I/O decorators
I don't like Java's I/O decorators
SE-2811
Dr. Mark L. Hornick
Dr. Yoder

7. Alternative Decorator Designs
SE-2811
5/23/2018
Alternative Decorator Designs x
SE-2811
Dr. Mark L. Hornick
Dr. Yoder

8. How to create a car with a sunroof and radio?
SE-2811
5/23/2018
How to create a car with a sunroof and radio?
SE-2811
Dr. Mark L. Hornick
Dr. Yoder

9. Decorator vs. Array of Add-ons
SE-2811
5/23/2018
Decorator vs. Array of Add-ons
What is the advantage of using your pattern?
SE-2811
Dr. Mark L. Hornick
Dr. Yoder

10. Decorator vs. Array of Add-ons
SE-2811
5/23/2018
Decorator vs. Array of Add-ons
SE-2811
Dr. Mark L. Hornick
Dr. Yoder

11. Downsides What are the disadvantages of decorators?
SE2811
5/23/2018
Downsides
What are the disadvantages of decorators?
See interview drama on p. 104 in the text (Head First)
Large number of small classes overwhelming to new developers
Problem when people rely on specific types without thinking through [TODO: Study & find example]
e.g. Consider the mess if the interface does not already exist for the class
Complexity of wrapping many to construct a new one
SE-2811
Dr. Mark L. Hornick
Dr. Josiah Yoder

12. https://www.polleverywhere.com/free_text_polls/zIp2tH2IVWjXv4H SE-2811
5/23/2018
Muddiest Point
SE-2811
Dr. Mark L. Hornick
Dr. Yoder

13. Threading Muddiest Point [To be revisited in a future lecture]
SE-2811
5/23/2018
Threading Muddiest Point [To be revisited in a future lecture]
All lambda examples the same code?
Lambda examples
When would you use a Lambda expression over an anonymous class and vice versa?
Lambda vs. Anon inner syntax
The Lambda is a Java thing, not an intelliJ thing right?
Java 8
whens the next quiz?
Quiz
Agree
More examples of using lambdas (didn't get exposure in software dev 2)
Effectively Final?
"Effectively Final"
SE-2811
Dr. Mark L. Hornick
Dr. Yoder

14. Patterns Muddiest Point [To be revisited in a future lecture]
SE-2811
5/23/2018
Patterns Muddiest Point [To be revisited in a future lecture]
We really didn't cover any sorting algorithms and what each's benefits are
Can we do an example???
Related to the quiz for below question
Do we need to implement code versions of the strategy and factory method patterns?? If so how extensive and will it be similar to how we implemented in class?
Implementing the methods needed for the factory method pattern.
Is there a flowchart/checklist to determine which pattern is more appropriate to use?
Choosing the correct design pattern
What are Coupling and Cohesion and is it better to have high or low coupling or cohesion?
On a quiz/test would you ask us to draw the uml of a particular general pattern, or would you just ask us to write the code?
Why would we use Factory Pattern?
How do you know when to use what pattern to solve a problem?
Diagrams
High/Low Cohesion/Coupling
Class Diagram for Factory Design Pattern
Nothing
Dr. Yoder

15. Decorator vs Strategy SE-2811 5/23/2018 Dr. Yoder SE-2811
Dr. Mark L. Hornick
Dr. Yoder