1. Slide design: Dr. Mark L. Hornick
SE-2811
5/6/2019
Week 6, Day 1: Decorator
Return Half-Exam 1 & Quiz 4 (I have them with me)
Decorators
Muddiest Point
SE-2811
Slide design: Dr. Mark L. Hornick
Content: Dr. Hornick
Errors: Dr. Yoder
Dr. Yoder

2. HW
SE-2811
5/6/2019
By Monday at 10am, to me a Writer decorator that implements a Caesar cipher.
The user should supply an integer key when creating the wrapper
The CaesarWriter should add the key to the value of each character that is written to the stream. If the value goes above 255, it should wrap around through 0.
Be sure to include the template write(String str, int off, int len) from ScrambleWriter
We will run and debug your code in class.
Dr. Yoder

3. (Review) (Byte) Output Streams
SE-2811
5/6/2019
(Review) (Byte) Output Streams
Byte output stream
(with other
Variables…)
SE-2811
Dr. Mark L. Hornick
Dr. Yoder

4. (Review) (Char) Writers
SE-2811
5/6/2019
(Review) (Char) Writers
OutputStreams write (8-bit) bytes.
Writers write 16-bit Unicode code-points
You can wrap a PrintWriter around a PrintStream
You cannot wrap a PrintStream around a PrintWriter (unless you write the code yourself.)
TODO: Copy some of the really cool code-points students found last year
SE-2811
Dr. Mark L. Hornick
Dr. Yoder

5. In-class exercise: Modify the code to de-scramble the stream
5/6/2019
In-class exercise: Modify the code to de-scramble the stream
Writer writer = new ScrambleWriter(new StarInserter(new PrintWriter( System.out)))); // Your code here: // End your code PrintWriter printWriter = new PrintWriter(writer,true);
SE-2811
Dr. Mark L. Hornick
Dr. Yoder

6. Design Principles T/? Reduce coupling T Increase cohesion
5/6/2019
Design Principles
T/? Reduce coupling
T Increase cohesion
T Encapsulate what varies
T Favor composition over inheritance
T Program to interfaces, not implementations
T Classes should be open for extension but closed for modification
Which of these are met?
(Avoid coupling)
Strive for loosely coupled designs between objects that interact
SE-2811
Dr. Mark L. Hornick
Dr. Josiah Yoder

7. Downsides What are the disadvantages of decorators? SE2811 5/6/2019
Large number of small classes overwhelming to new developers
Problem when people rely on specific types without thinking through [TODO: Study & find example]
Complexity of wrapping
SE-2811
Dr. Mark L. Hornick
Dr. Josiah Yoder

8. https://www.polleverywhere.com/free_text_polls/zIp2tH2IVWjXv4H SE-2811
5/6/2019
Muddiest Point
SE-2811
Dr. Mark L. Hornick
Dr. Yoder

9. Threading Muddiest Point [To be revisited in a future lecture]
SE-2811
5/6/2019
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

10. Patterns Muddiest Point [To be revisited in a future lecture]
SE-2811
5/6/2019
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