CSE460 Lecture 14

Software Analysis and Design
Decorator
(202103)

Transcript

1. jgs
   CSE 460
   Software Analysis and Design
   Lecture 14: Structural Patterns - Decorator
   Dr. Javier Gonzalez-Sanchez
   javiergs@asu.edu
   javiergs.engineering.asu.edu | javiergs.com
   PERALTA 230U
   Office Hours: By appointment
   

   View Slide

2. jgs
   00000001
   Announcement
   § Midterm Exam
   Wednesday March 10
   During the lecture time. No exceptions
   § Final Exam
   Wednesday April 21
   During the lecture time. No exceptions
   

   View Slide

3. jgs
   00000001
   GoF Patterns
   

   View Slide

4. jgs
   00000001
   Decorator
   

   View Slide

5. jgs
   00000001
   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.
   

   View Slide

6. jgs
   00000001
   Decorator
   

   View Slide

7. jgs
   00000001
   Decorator
   

   View Slide

8. jgs
   00000001
   Component
   abstract class Component {
   public abstract void operation();
   }
   

   View Slide

9. jgs
   00000001
   ConcreteComponent
   class ConcreteComponent extends Component {
   @override
   public void operation() {
   System.out.print("ConcreteComponent-Operation()");
   }
   }
   

   View Slide

10. jgs
    00000001
    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();
    }
    }
    }
    

    View Slide

11. jgs
    00000001
    ConcreteDecoratorA
    class ConcreteDecoratorA extends Decorator {
    @override
    public void operation() {
    super.operation();
    System.out.println("ConcreteDecoratorA-Operation()”);
    }
    }
    

    View Slide

12. jgs
    00000001
    ConcreteDecoratorB
    class ConcreteDecoratorB extends Decorator {
    @override
    public void operation() {
    super.operation();
    addedBehavior();
    System.out.println("ConcreteDecoratorB-Operation()");
    }
    void addedBehavior() {
    }
    }
    

    View Slide

13. jgs
    00000001
    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();
    }
    }
    

    View Slide

14. jgs
    00000001
    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()
    

    View Slide

15. jgs
    00000001
    Scenario
    CompanionHelper
    CompanionTroll
    Companion
    

    View Slide

16. jgs
    00000001
    Scenario
    CompanionHelper
    CompanionTroll
    Companion
    CompanionTrollHelper
    

    View Slide

17. jgs
    00000001
    Scenario
    CompanionHelper
    CompanionTroll
    Companion
    CompanionTrollHelper
    

    View Slide

18. jgs
    Example 1
    Text Mode
    

    View Slide

19. jgs
    00000001
    Decorator
    

    View Slide

20. jgs
    00000001
    Main
    

    View Slide

21. jgs
    00000001
    Companion
    public interface Companion {
    public void doSomething();
    }
    

    View Slide

22. jgs
    00000001
    BasicCompanion
    public class BasicCompanion implements Companion {
    @Override
    public void doSomething() {
    System.out.print("Hello Student, ");
    }
    }
    

    View Slide

23. jgs
    00000001
    CompanionDecorator
    public class CompanionDecorator implements Companion {
    protected Companion c;
    public void add(Companion c){
    this.c = c;
    }
    @Override
    public void doSomething() {
    this.c.doSomething();
    }
    }
    

    View Slide

24. jgs
    00000001
    HelperCompanion
    public class HelperCompanion extends CompanionDecorator {
    @Override
    public void doSomething(){
    super.doSomething();
    System.out.print(" I am here to help you. ");
    }
    }
    

    View Slide

25. jgs
    00000001
    AffectiveCompanion
    public class AffectiveCompanion extends CompanionDecorator {
    @Override
    public void doSomething(){
    super.doSomething();
    System.out.print(" I am here to cheer you.");
    }
    }
    

    View Slide

26. jgs
    00000001
    Main
    

    View Slide

27. jgs
    CSE 460 Software Analysis and Design
    Javier Gonzalez-Sanchez
    javiergs@asu.edu
    Fall 2020
    Disclaimer. These slides can only be used as study material for the class CSE460 at ASU. They cannot be distributed or used for another purpose.
    

    View Slide