CSC308B Lecture 12

jgs CSC 308 Software Engineering 1 Lecture 12: Patterns II
Dr. Javier Gonzalez-Sanchez [email protected] www.javiergs.com Building 14 -227

jgs Previously …

jgs Javier Gonzalez-Sanchez | CSC 308 | Winter 2024 |
3 Scenario Observer + update() Observable + addObserver() + notifyObservers() + setChanged() Teacher Student Main

4 Homework Reading

5 Important Depreciated java.util.Observer java.util.Observable The implementation of these packages That is NOT about the Observer pattern being depreciated.

6 Important Use java.beans.PropertyChangeListener java.beans.PropertyChangeSupport

jgs Test Yourselves

8 NumberGenerator.java

9 Screen.java

10 Main.java

11 Let’s Work UML Diagram?

jgs Singleton

13 GoF Patterns

14 Singleton

15 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

16 class Singleton{ private static Singleton _instance; // Constructor is 'protected' protected Singleton() {} public static Singleton getInstance(){ if (_instance == null){ _instance = new Singleton(); } return _instance; } } Singleton

jgs Decorator & Composite Design Patterns

18 GoF Patterns

19 Decorator

20 Decorator

21 Decorator

22 abstract class Component { public abstract void operation(); } Component

23 class ConcreteComponent extends Component { @override public void operation() { System.out.print("ConcreteComponent-Operation()"); } } ConcreteComponent

24 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

25 class ConcreteDecoratorA extends Decorator { @override public void operation() { super.operation(); System.out.println("ConcreteDecoratorA-Operation()”); } } ConcreteDecoratorA

26 class ConcreteDecoratorB extends Decorator { @override public void operation() { super.operation(); addedBehavior(); System.out.println("ConcreteDecoratorB-Operation()"); } void addedBehavior() { } } ConcreteDecoratorB

27 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

28 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()

29 Questions

jgs CSC 308 Software Engineering 1 Lab 11: Project Sprint
2 (Continue) Dr. Javier Gonzalez-Sanchez [email protected] www.javiergs.com Building 14 -227 Office Hours: By appointment

33 Scenario (1) Repository is a Singleton It stores the information for Squares and circles objects (2) A CircleBuilder is a Runnable Creating circles 1 per second At random places (3) A BoxBuilder is a Runnable Creating boxes 1 per second At random places (4) A Screen is a Panel Drawing the circles and boxes observed in the Whiteboard (5) And we need a Main that assembly everything and provide a Frame

34 Let’s Work

jgs CSC 308 Software Engineering I Javier Gonzalez-Sanchez, Ph.D. [email protected]
Winter 2024 Copyright. These slides can only be used as study material for the class CSC 308 at Cal Poly. They cannot be distributed or used for another purpose.

CSC308B Lecture 12

CSC308B Lecture 12

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