CSE564 Lecture 17

Software Design
More Design Patterns
(202110)

Transcript

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   CSE 564
   Software Design
   Lecture 17: More Patterns
   Dr. Javier Gonzalez-Sanchez
   javiergs@asu.edu
   javiergs.engineering.asu.edu | javiergs.com
   PERALTA 230U
   Office Hours: By appointment
   

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   GoF Patterns
   

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   Factory
   Wrapper of a constructor
   One entire object to be built in a single method call
   

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   Abstract Factory
   

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   Products
   public interface Shape {
   void draw();
   }
   public class RoundedRectangle implements Shape {
   public void draw() {
   System.out.println("Inside RoundedRectangle/draw() method.");
   }
   }
   public class RoundedSquare implements Shape {
   public void draw() {
   System.out.println("Inside RoundedSquare/draw() method.");
   }
   }
   public class Rectangle implements Shape {
   public void draw() {
   System.out.println("Inside Rectangle/draw() method.");
   }
   }
   

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   Factories
   public abstract class AbstractFactory {
   Shape getShape(String shapeType) ;
   }
   public class ShapeFactory extends AbstractFactory {
   public Shape getShape(String shapeType){
   if(shapeType.equalsIgnoreCase("RECTANGLE")){
   return new Rectangle();
   }else if(shapeType.equalsIgnoreCase("SQUARE")){
   return new Square();
   }
   return null;
   }
   }
   

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   Factories
   public class RoundedShapeFactory extends AbstractFactory {
   public Shape getShape(String shapeType){
   if(shapeType.equalsIgnoreCase("RECTANGLE")){
   return new RoundedRectangle();
   }else if(shapeType.equalsIgnoreCase("SQUARE")){
   return new RoundedSquare();
   }
   return null;
   }
   }
   

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   Client
   public class Client {
   public static void main(String[] args) {
   AbstractFactory shapeFactory = new ShapeFactory();
   //get an object of Shape Rectangle
   Shape shape1 = shapeFactory.getShape("RECTANGLE");
   //call draw method of Shape Rectangle
   shape1.draw();
   //get an object of Shape Square
   Shape shape2 = shapeFactory.getShape("SQUARE");
   //call draw method of Shape Square
   shape2.draw(); ]
   //get shape factory
   AbstractFactory shapeFactory1 = new RoundedShapeFactory();
   //get an object of Shape Rectangle
   Shape shape3 = shapeFactory1.getShape("RECTANGLE");
   //call draw method of Shape Rectangle
   shape3.draw();
   //get an object of Shape Square
   Shape shape4 = shapeFactory1.getShape("SQUARE");
   //call draw method of Shape Square
   shape4.draw();
   }
   }
   

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   Test Yourselves
   

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    Workspace.java (part 1 / 2)
    

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    User
    D
    B
    A
    C
    

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    The System
    D
    B
    A
    C
    random
    

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    Chain of Responsibility
    Avoid coupling the sender of a request to its receiver
    by giving more than one object a chance to handle the
    request.
    

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    Chain of Responsibility
    

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    Chain of Responsibility
    // Setup Chain of Responsibility
    Handler h1 = new ConcreteHandler2();
    Handler h2 = new ConcreteHandler2();
    Handler h3 = new ConcreteHandler1();
    h1.SetSuccessor(h2);
    h2.SetSuccessor(h3);
    // Generate and process request
    int[] requests = { 2, 5, 14, 22, 18, 3, 27, 20 };
    foreach (int i=0; ih1.HandleRequest(request[i]);
    }
    

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    Handler
    abstract class Handler {
    public abstract void HandleRequest(int request);
    }
    class ConcreteHandler1 extends Handler {
    public override void HandleRequest(int request) {
    if (request >= 0 && request < 10) {
    // code here…
    } else if (successor != null) {
    successor.HandleRequest(request);
    }
    }
    }
    

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    Handler
    class ConcreteHandler2 extends Handler {
    protected Handler successor;
    public void setSuccessor(Handler successor) {
    this.successor = successor;
    }
    public override void HandleRequest(int request) {
    if (request >= 10 && request < 20) {
    // code here
    } else if (successor != null) {
    successor.HandleRequest(request);
    }
    }
    }
    

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    Chain of Responsibility vs Composite vs Decorator
    

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    Test Yourselves
    

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    The System
    D
    B
    A
    C
    D
    B
    A
    C
    Clustering
    TSP -Nearest Neighbor
    

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    Questions
    

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    CSE 564 Software Design
    Javier Gonzalez-Sanchez, Ph.D.
    javiergs@asu.edu
    Fall 2021
    Copyright. These slides can only be used as study material for the class CSE564 at ASU.
    They cannot be distributed or used for another purpose.
    

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