CSC308 Lecture 13

Software Engineering I
Design Patterns - Decorator/Composite
(202210)

Transcript

1. jgs CSC 308 Software Engineering I Lecture 13: 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
2. jgs Fall 2022 | 00000010 GoF Patterns
3. jgs Fall 2022 | 00000010 Decorator
4. jgs Fall 2022 | 00000010 Decorator vs Inheritance § 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.
5. jgs Fall 2022 | 00000010 Decorator
6. jgs Fall 2022 | 00000010 Decorator
7. jgs Fall 2022 | 00000010 Component abstract class Component { public abstract void operation(); }
8. jgs Fall 2022 | 00000010 ConcreteComponent class ConcreteComponent extends Component { @override public void operation() { System.out.print("ConcreteComponent-Operation()"); } }
9. jgs Fall 2022 | 00000010 Decorator 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(); } } }
10. jgs Fall 2022 | 00000010 ConcreteDecoratorA class ConcreteDecoratorA extends Decorator { @override public void operation() { super.operation(); System.out.println("ConcreteDecoratorA-Operation()”); } }
11. jgs Fall 2022 | 00000010 ConcreteDecoratorB class ConcreteDecoratorB extends Decorator { @override public void operation() { super.operation(); addedBehavior(); System.out.println("ConcreteDecoratorB-Operation()"); } void addedBehavior() { } }
12. jgs Fall 2022 | 00000010 Main 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(); } }
13. jgs Fall 2022 | 00000010 Main 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(); } } ConcreteComponent - Operation() ConcreteDecoratorA - Operation() ConcreteDecoratorB - Operation()
14. jgs Fall 2022 | 00000010 Scenario CompanionHelper CompanionTroll Companion
15. jgs Fall 2022 | 00000010 Scenario CompanionHelper CompanionTroll Companion CompanionTrollHelper
16. jgs Fall 2022 | 00000010 Scenario CompanionHelper CompanionTroll Companion CompanionTrollHelper
17. jgs Example 1 Text Mode
18. jgs Fall 2022 | 00000010 Decorator
19. jgs Fall 2022 | 00000010 Main
20. jgs Fall 2022 | 00000010 Companion public interface Companion { public void doSomething(); }
21. jgs Fall 2022 | 00000010 BasicCompanion public class BasicCompanion implements Companion { @Override public void doSomething() { System.out.print("Hello Student, "); } }
22. jgs Fall 2022 | 00000010 CompanionDecorator public class CompanionDecorator implements Companion { protected Companion c; public void add(Companion c){ this.c = c; } @Override public void doSomething() { this.c.doSomething(); } }
23. jgs Fall 2022 | 00000010 HelperCompanion public class HelperCompanion extends CompanionDecorator { @Override public void doSomething(){ super.doSomething(); System.out.print(" I am here to help you. "); } }
24. jgs Fall 2022 | 00000010 AffectiveCompanion public class AffectiveCompanion extends CompanionDecorator { @Override public void doSomething(){ super.doSomething(); System.out.print(" I am here to cheer you."); } }
25. jgs Fall 2022 | 00000010 Main
26. jgs Fall 2022 | 00000010 Questions
27. jgs
28. jgs CSC 308 Software Engineering I Lab 12: Patterns Dr. Javier Gonzalez-Sanchez javiergs@calpoly.edu users.csc.calpoly.edu/~javiergs | javiergs.com Building 14 -227 Office Hours: By appointment
29. jgs Test Yourselves Class Diagram
30. jgs Fall 2022 | 00000010 Scenario
31. jgs Fall 2022 | 00000010 Let’s Work Nothing to submit yet
32. jgs Fall 2022 | 00000010 Questions
33. jgs CSC 308 Software Engineering I Javier Gonzalez-Sanchez, Ph.D. javiergs@calpoly.edu Fall 2022 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.