Decorator Pattern 1 : Decorator Pattern « Design Pattern « Java

1. Java
2. Design Pattern
3. Decorator Pattern

Decorator Pattern 1

//[C] 2002 Sun Microsystems, Inc.---

import java.io.File;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.Iterator;

public class RunDecoratorPattern {
    public static void main(String [] arguments){
        System.out.println("Example for the Decorator pattern");
        System.out.println();
        System.out.println("This demonstration will show how Decorator classes can be used");
        System.out.println(" to extend the basic functionality of ProjectItems. The Task and");
        System.out.println(" Deliverable classes provide the basic ProjectItems, and their");
        System.out.println(" functionality will be extended by adding subclasses of the");
        System.out.println(" abstract class ProjectDecorator.");
        System.out.println();
        System.out.println("Note that the toString method has been overridden for all ProjectItems,");
        System.out.println(" to more effectively show how Decorators are associated with their");
        System.out.println(" ProjectItems.");
        System.out.println();
        
        System.out.println("Creating ProjectItems.");
        Contact contact1 = new ContactImpl("Simone", "Roberto", "Head Researcher and Chief Archivist", "Institute for Advanced (Java) Studies");
        Task task1 = new Task("Perform months of diligent research", contact1, 20.0);
        Task task2 = new Task("Obtain grant from World Java Foundation", contact1, 40.0);
        Deliverable deliverable1 = new Deliverable("Java History", "Comprehensive history of the design of all Java APIs", contact1);
        System.out.println("ProjectItem objects created. Results:");
        System.out.println(task1);
        System.out.println(task2);
        System.out.println(deliverable1);
        System.out.println();
        
        System.out.println("Creating decorators");
        ProjectDecorator decorator1 = new SupportedProjectItem(new File("JavaHistory.txt"));
        ProjectDecorator decorator2 = new DependentProjectItem(task2);
        System.out.println("Decorators created. Adding decorators to the first task");
        decorator1.setProjectItem(task1);
        decorator2.setProjectItem(decorator1);
        System.out.println();
        System.out.println("Decorators added. Results");
        System.out.println(decorator2);
        
        System.out.println("");
    }
}

interface Contact extends Serializable{
    public static final String SPACE = " ";
    public String getFirstName();
    public String getLastName();
    public String getTitle();
    public String getOrganization();
    
    public void setFirstName(String newFirstName);
    public void setLastName(String newLastName);
    public void setTitle(String newTitle);
    public void setOrganization(String newOrganization);
}

class ContactImpl implements Contact{
    private String firstName;
    private String lastName;
    private String title;
    private String organization;
    
    public ContactImpl(){}
    public ContactImpl(String newFirstName, String newLastName,
        String newTitle, String newOrganization){
            firstName = newFirstName;
            lastName = newLastName;
            title = newTitle;
            organization = newOrganization;
    }
    
    public String getFirstName(){ return firstName; }
    public String getLastName(){ return lastName; }
    public String getTitle(){ return title; }
    public String getOrganization(){ return organization; }
    
    public void setFirstName(String newFirstName){ firstName = newFirstName; }
    public void setLastName(String newLastName){ lastName = newLastName; }
    public void setTitle(String newTitle){ title = newTitle; }
    public void setOrganization(String newOrganization){ organization = newOrganization; }
    
    public String toString(){
        return firstName + SPACE + lastName;
    }
}

class Deliverable implements ProjectItem{
    private String name;
    private String description;
    private Contact owner;
    
    public Deliverable(){ }
    public Deliverable(String newName, String newDescription,
        Contact newOwner){
        name = newName;
        description = newDescription;
        owner = newOwner;
    }
    
    public String getName(){ return name; }
    public String getDescription(){ return description; }
    public Contact getOwner(){ return owner; }
    public double getTimeRequired(){ return 0; }
    
    public void setName(String newName){ name = newName; }
    public void setDescription(String newDescription){ description = newDescription; }
    public void setOwner(Contact newOwner){ owner = newOwner; }
    
    public String toString(){
        return "Deliverable: " + name;
    }
}

class DependentProjectItem extends ProjectDecorator{
    private ProjectItem dependentItem;
    
    public DependentProjectItem(){ }
    public DependentProjectItem(ProjectItem newDependentItem){
        dependentItem = newDependentItem;
    }
    
    public ProjectItem getDependentItem(){ return dependentItem; }
    
    public void setDependentItem(ProjectItem newDependentItem){ dependentItem = newDependentItem; }
    
    public String toString(){
        return getProjectItem().toString() + EOL_STRING
            + "\tProjectItem dependent on: " + dependentItem;
    }
}

abstract class ProjectDecorator implements ProjectItem{
    private ProjectItem projectItem;
    
    protected ProjectItem getProjectItem(){ return projectItem; }
    public void setProjectItem(ProjectItem newProjectItem){ projectItem = newProjectItem; }
    
    public double getTimeRequired(){
        return projectItem.getTimeRequired();
    }
}

interface ProjectItem extends Serializable{
    public static final String EOL_STRING = System.getProperty("line.separator");
    public double getTimeRequired();
}

class Task implements ProjectItem{
    private String name;
    private ArrayList projectItems = new ArrayList();
    private Contact owner;
    private double timeRequired;
    
    public Task(){ }
    public Task(String newName, Contact newOwner,
        double newTimeRequired){
        name = newName;
        owner = newOwner;
        timeRequired = newTimeRequired;
    }
    
    public String getName(){ return name; }
    public ArrayList getProjectItems(){ return projectItems; }
    public Contact getOwner(){ return owner; }
    public double getTimeRequired(){
        double totalTime = timeRequired;
        Iterator items = projectItems.iterator();
        while(items.hasNext()){
            ProjectItem item = (ProjectItem)items.next();
            totalTime += item.getTimeRequired();
        }
        return totalTime;
    }
    
    public void setName(String newName){ name = newName; }
    public void setOwner(Contact newOwner){ owner = newOwner; }
    public void setTimeRequired(double newTimeRequired){ timeRequired = newTimeRequired; }
    
    public void addProjectItem(ProjectItem element){
        if (!projectItems.contains(element)){
            projectItems.add(element);
        }
    }
    public void removeProjectItem(ProjectItem element){
        projectItems.remove(element);
    }
    
    public String toString(){
        return "Task: " + name;
    }
}

class SupportedProjectItem extends ProjectDecorator{
    private ArrayList supportingDocuments = new ArrayList();
    
    public SupportedProjectItem(){ }
    public SupportedProjectItem(File newSupportingDocument){
        addSupportingDocument(newSupportingDocument);
    }
    
    public ArrayList getSupportingDocuments(){
        return supportingDocuments;
    }
    
    public void addSupportingDocument(File document){
        if (!supportingDocuments.contains(document)){
            supportingDocuments.add(document);
        }
    }
    
    public void removeSupportingDocument(File document){
        supportingDocuments.remove(document);
    }
    
    public String toString(){
        return getProjectItem().toString() + EOL_STRING
            + "\tSupporting Documents: " + supportingDocuments;
    }
}

           
       

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