CSC308 Lecture 16

Software Engineering I
Design Patterns - Decorator/Composite
(202211)

Transcript

1. jgs CSC 308 Software Engineering 1 Lecture 16: Design Patterns – Decorator/Composite Dr. Javier Gonzalez-Sanchez javiergs@calpoly.edu www.javiergs.com Building 14 -227 Office Hours: By appointment
2. jgs CSC 308 Software Engineering I Lecture 16: Design Patterns – Decorator/Composite Dr. Javier Gonzalez-Sanchez javiergs@calpoly.edu users.csc.calpoly.edu/~javiergs | javiergs.com Building 14 -227 Office Hours: By appointment
3. jgs Previously … Design Patterns
4. jgs Javier Gonzalez-Sanchez | CSC 308 | Winter 2023 | 4 GoF Patterns
5. jgs Javier Gonzalez-Sanchez | CSC 308 | Winter 2023 | 5 Singleton
6. jgs Javier Gonzalez-Sanchez | CSC 308 | Winter 2023 | 6 class MainApp { public static void Main(String []a){ // Constructor is protected -- cannot use new Singleton s1 = Singleton.getInstance(); Singleton s2 = Singleton.getInstance(); // Test for same instance if (s1 == s2){ // true - Objects are the same instance } } } Singleton
7. jgs Javier Gonzalez-Sanchez | CSC 308 | Winter 2023 | 7 class Singleton{ private static Singleton _instance; // Constructor is 'protected' protected Singleton() {} public static Singleton getInstance(){ if (_instance == null){ _instance = new Singleton(); } return _instance; } } Singleton
8. jgs Decorator & Composite Design Patterns
9. jgs Javier Gonzalez-Sanchez | CSC 308 | Winter 2023 | 9 GoF Patterns
10. jgs Javier Gonzalez-Sanchez | CSC 308 | Winter 2023 | 10 Decorator
11. jgs Javier Gonzalez-Sanchez | CSC 308 | Winter 2023 | 11 Decorator
12. jgs Javier Gonzalez-Sanchez | CSC 308 | Winter 2023 | 12 Decorator
13. jgs Javier Gonzalez-Sanchez | CSC 308 | Winter 2023 | 13 abstract class Component { public abstract void operation(); } Component
14. jgs Javier Gonzalez-Sanchez | CSC 308 | Winter 2023 | 14 class ConcreteComponent extends Component { @override public void operation() { System.out.print("ConcreteComponent-Operation()"); } } ConcreteComponent
15. jgs Javier Gonzalez-Sanchez | CSC 308 | Winter 2023 | 15 abstract class Decorator extends Component { protected Component component; public void setComponent(Component component) { this.component = component; } @override public void operation() { if (component != null) { component.operation(); } } } Decorator
16. jgs Javier Gonzalez-Sanchez | CSC 308 | Winter 2023 | 16 class ConcreteDecoratorA extends Decorator { @override public void operation() { super.operation(); System.out.println("ConcreteDecoratorA-Operation()”); } } ConcreteDecoratorA
17. jgs Javier Gonzalez-Sanchez | CSC 308 | Winter 2023 | 17 class ConcreteDecoratorB extends Decorator { @override public void operation() { super.operation(); addedBehavior(); System.out.println("ConcreteDecoratorB-Operation()"); } void addedBehavior() { } } ConcreteDecoratorB
18. jgs Javier Gonzalez-Sanchez | CSC 308 | Winter 2023 | 18 class MainApp { static void main() { // Create ConcreteComponent and two Decorators ConcreteComponent c = new ConcreteComponent(); ConcreteDecoratorA d1 = new ConcreteDecoratorA(); ConcreteDecoratorB d2 = new ConcreteDecoratorB(); // Link decorators d1.SetComponent(c); d2.SetComponent(d1); d2.Operation(); } } Main
19. jgs Javier Gonzalez-Sanchez | CSC 308 | Winter 2023 | 19 class MainApp { static void main() { // Create ConcreteComponent and two Decorators ConcreteComponent c = new ConcreteComponent(); ConcreteDecoratorA d1 = new ConcreteDecoratorA(); ConcreteDecoratorB d2 = new ConcreteDecoratorB(); // Link decorators d1.SetComponent(c); d2.SetComponent(d1); d2.Operation(); } } Main ConcreteComponent - Operation() ConcreteDecoratorA - Operation() ConcreteDecoratorB - Operation()
20. jgs Javier Gonzalez-Sanchez | CSC 308 | Winter 2023 | 20 § Both allow you to change how an object behaves § The decorator pattern can be used to make it possible to extend (decorate) the functionality of a certain object at runtime. § Inheritance adds behavior at compilation-time. Decorator vs Inheritance
21. jgs Javier Gonzalez-Sanchez | CSC 308 | Winter 2023 | 21 Scenario CompanionHelper CompanionTroll Companion
22. jgs Javier Gonzalez-Sanchez | CSC 308 | Winter 2023 | 22 Scenario CompanionHelper CompanionTroll Companion CompanionTrollHelper
23. jgs Javier Gonzalez-Sanchez | CSC 308 | Winter 2023 | 23 Scenario CompanionHelper CompanionTroll Companion CompanionTrollHelper
24. jgs Example 1 Text Mode
25. jgs Javier Gonzalez-Sanchez | CSC 308 | Winter 2023 | 25 Decorator
26. jgs Javier Gonzalez-Sanchez | CSC 308 | Winter 2023 | 26 Main
27. jgs Javier Gonzalez-Sanchez | CSC 308 | Winter 2023 | 27 public interface Companion { public void doSomething(); } Companion
28. jgs Javier Gonzalez-Sanchez | CSC 308 | Winter 2023 | 28 public class BasicCompanion implements Companion { @Override public void doSomething() { System.out.print("Hello Student, "); } } BasicCompanion
29. jgs Javier Gonzalez-Sanchez | CSC 308 | Winter 2023 | 29 public class CompanionDecorator implements Companion { protected Companion c; public void add(Companion c){ this.c = c; } @Override public void doSomething() { this.c.doSomething(); } } CompanionDecorator
30. jgs Javier Gonzalez-Sanchez | CSC 308 | Winter 2023 | 30 public class HelperCompanion extends CompanionDecorator { @Override public void doSomething(){ super.doSomething(); System.out.print(" I am here to help you. "); } } HelperCompanion
31. jgs Javier Gonzalez-Sanchez | CSC 308 | Winter 2023 | 31 public class AffectiveCompanion extends CompanionDecorator { @Override public void doSomething(){ super.doSomething(); System.out.print(" I am here to cheer you."); } } AffectiveCompanion
32. jgs Javier Gonzalez-Sanchez | CSC 308 | Winter 2023 | 32 Main
33. jgs Javier Gonzalez-Sanchez | CSC 308 | Winter 2023 | 33 Questions
34. jgs Javier Gonzalez-Sanchez | CSC 308 | Winter 2023 | 34 Office Hours Tuesday and Thursday 3 - 5 pm But an appointment required Sent me an email – javiergs@calpoly.edu
35. jgs
36. jgs CSC 308 Software Engineering 1 Lab 16: Design Patterns Dr. Javier Gonzalez-Sanchez javiergs@calpoly.edu www.javiergs.com Building 14 -227 Office Hours: By appointment
37. jgs Test Yourselves Class Diagram
38. jgs Javier Gonzalez-Sanchez | CSC 308 | Winter 2023 | 38 Scenario
39. jgs Javier Gonzalez-Sanchez | CSC 308 | Winter 2023 | 39 Let’s Work
40. jgs CSC 308 Software Engineering I Javier Gonzalez-Sanchez, Ph.D. javiergs@calpoly.edu Winter 2023 Copyright. These slides can only be used as study material for the class CSC308 at Cal Poly. They cannot be distributed or used for another purpose.