CSE360 Flipped Lecture 06

Introduction to Software Engineering
Objects and Patterns
(202010)

Transcript

1. CSE 360 Introduction to Software Engineering Lecture 06: Objects and Patterns Dr. Javier Gonzalez-Sanchez javiergs@asu.edu javiergs.engineering.asu.edu | javiergs.com PERALTA 230U Office Hours: By appointment
2. Key Ideas CSE360
3. Javier Gonzalez-Sanchez | CSE360 | Fall 2020 | 3 Key Concepts Encapsulation Abstraction Hierarchical Relationships Polymorphism Concurrency Persistency
4. Javier Gonzalez-Sanchez | CSE360 | Fall 2020 | 4 Abstraction • Reducing by focusing on the essential observable behavior • What will be outside? OOAD, Booch Textbook
5. Javier Gonzalez-Sanchez | CSE360 | Fall 2020 | 5 Encapsulation • Hiding the details of the implementation • What is inside? OOAD, Booch Textbook
6. Javier Gonzalez-Sanchez | CSE360 | Fall 2020 | 6 Hierarchical Relationships • Creating a hierarchy of abstractions • Who (is a…, uses a…, has a…) ? OOAD, Booch Textbook
7. Javier Gonzalez-Sanchez | CSE360 | Fall 2020 | 7 Hierarchical Relationships Association Aggregation Composition Generalization Realization
8. Javier Gonzalez-Sanchez | CSE360 | Fall 2020 | 8 8 Hierarchical Relationships
9. Javier Gonzalez-Sanchez | CSE360 | Fall 2020 | 9 Polymorphism • The condition of denoting different forms. • A single name may denote objects of many different classes that are related by some common superclass. • When to use it?
10. Javier Gonzalez-Sanchez | CSE360 | Fall 2020 | 10 High cohesion Low coupling Important
11. Next Step
12. Javier Gonzalez-Sanchez | CSE360 | Fall 2020 | 12 The LEGO Paradigm
13. Javier Gonzalez-Sanchez | CSE360 | Fall 2020 | 13 Patterns are these Blocks • Design patterns are solutions to software design problems you find again and again in real-world application development. • Patterns are about reusable designs and interactions between objects. • The 23 Gang of Four (GoF) patterns are generally considered the foundation for all other patterns (Gamma, Helm, Johnson, and Vlissides).
14. Javier Gonzalez-Sanchez | CSE360 | Fall 2020 | 14 GoF Patterns
15. Javier Gonzalez-Sanchez | CSE360 | Fall 2020 | 15 Blueprint
16. Javier Gonzalez-Sanchez | CSE360 | Fall 2020 | 16 GoF Patterns
17. Javier Gonzalez-Sanchez | CSE360 | Fall 2020 | 17 Observer
18. Javier Gonzalez-Sanchez | CSE360 | Fall 2020 | 18 Observer
19. Javier Gonzalez-Sanchez | CSE360 | Fall 2020 | 19 Observer Java Listeners
20. Javier Gonzalez-Sanchez | CSE360 | Fall 2020 | 20 GoF Patterns
21. Javier Gonzalez-Sanchez | CSE360 | Fall 2020 | 21 Decorator
22. Javier Gonzalez-Sanchez | CSE360 | Fall 2020 | 22 Examples
23. Javier Gonzalez-Sanchez | CSE360 | Fall 2020 | 23 Decorator
24. Javier Gonzalez-Sanchez | CSE360 | Fall 2020 | 24 Examples Java UI Objects
25. To be continued… Review the code in the slides at the end with examples of Observer and Decorator
26. Observer Pattern Example with Java API
27. Javier Gonzalez-Sanchez | CSE360 | Fall 2020 | 27 Scenario Observer + update() Observable + addObserver() + notifyObservers() + setChanged() Tutor Student Classroom
28. Javier Gonzalez-Sanchez | CSE360 | Fall 2020 | 28 Student import java.util.Observable; import java.util.Observer; public class Student implements Observer { public String answerQuestion (String question) { return "I am thinking about \'" + question +"\'"; } @Override public void update(Observable o, Object arg) { String x = ((Tutor)o).getQuestion(); String y = this.answerQuestion(x); System.out.println(y); } }
29. Javier Gonzalez-Sanchez | CSE360 | Fall 2020 | 29 Tutor import java.util.Observable; public class Tutor extends Observable { private String [] questions = { "2 + 2", "public or private", "functional or not fuctional", "white or black" }; private String theQuestion; public void askQuestion() { theQuestion = questions[((int)(Math.random()*10))%4]; setChanged(); notifyObservers(); } public String getQuestion() { return theQuestion; } }
30. Javier Gonzalez-Sanchez | CSE360 | Fall 2020 | 30 Classroom public class Classroom { public static void main(String[] args) { Student student = new Student(); Tutor tutor = new Tutor(); tutor.addObserver(student); for (int i=0; i<5;i++) tutor.askQuestion(); } }
31. Javier Gonzalez-Sanchez | CSE360 | Fall 2020 | 31 Output
32. Decorator Pattern Example with Java
33. Javier Gonzalez-Sanchez | CSE360 | Fall 2020 | 33 Decorator
34. Javier Gonzalez-Sanchez | CSE360 | Fall 2020 | 34 Main
35. Javier Gonzalez-Sanchez | CSE360 | Fall 2020 | 35 Companion public interface Companion { public void doSomething(); }
36. Javier Gonzalez-Sanchez | CSE360 | Fall 2020 | 36 BasicCompanion public class BasicCompanion implements Companion { @Override public void doSomething() { System.out.print("Hello Student, "); } }
37. Javier Gonzalez-Sanchez | CSE360 | Fall 2020 | 37 CompanionDecorator public class CompanionDecorator implements Companion { protected Companion c; public void add(Companion c){ this.c = c; } @Override public void doSomething() { this.c.doSomething(); } }
38. Javier Gonzalez-Sanchez | CSE360 | Fall 2020 | 38 HelperCompanion public class HelperCompanion extends CompanionDecorator { @Override public void doSomething(){ super.doSomething(); System.out.print(" I am here to help you. "); } }
39. Javier Gonzalez-Sanchez | CSE360 | Fall 2020 | 39 AffectiveCompanion public class AffectiveCompanion extends CompanionDecorator { @Override public void doSomething(){ super.doSomething(); System.out.print(" I am here to cheer you."); } }
40. Javier Gonzalez-Sanchez | CSE360 | Fall 2020 | 40 Homework Complete This Week’s Hybrid Activities
41. Javier Gonzalez-Sanchez | CSE360 | Fall 2020 | 41 References Chapter 5
42. CSE360 – Introduction to Software Engineering Javier Gonzalez-Sanchez javiergs@asu.edu Fall 2020 Disclaimer. These slides can only be used as study material for the class CSE360 at ASU. They cannot be distributed or used for another purpose.