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Sablonul de proiectare Composite

Descriere

Sablonul structural este un sablon prin intermediul caruia se poate construi o ierarhie de obiecte care pot fi tratate ca un singur obiect. Sablonul construieste un obiect care contine referinte catre obiecte de acelasi fel.

Diagrama UML

Exemplu

Pentru exemplificare vom folosi exemplul: 

import java.util.ArrayList;
import java.util.List;
 
public class Employee {
   private String name;
   private String dept;
   private int salary;
   private List<Employee> subordinates;
 
   // constructor
   public Employee(String name,String dept, int sal) {
      this.name = name;
      this.dept = dept;
      this.salary = sal;
      subordinates = new ArrayList<Employee>();
   }
 
   public void add(Employee e) {
      subordinates.add(e);
   }
 
   public void remove(Employee e) {
      subordinates.remove(e);
   }
 
   public List<Employee> getSubordinates(){
     return subordinates;
   }
 
   public String toString(){
      return ("Employee :[ Name : " + name + ", dept : " + dept + ", salary :" + salary+" ]");
   }   
}
 
public class CompositePatternDemo {
   public static void main(String[] args) {
 
      Employee CEO = new Employee("John","CEO", 30000);
 
      Employee headSales = new Employee("Robert","Head Sales", 20000);
 
      Employee headMarketing = new Employee("Michel","Head Marketing", 20000);
 
      Employee clerk1 = new Employee("Laura","Marketing", 10000);
      Employee clerk2 = new Employee("Bob","Marketing", 10000);
 
      Employee salesExecutive1 = new Employee("Richard","Sales", 10000);
      Employee salesExecutive2 = new Employee("Rob","Sales", 10000);
 
      CEO.add(headSales);
      CEO.add(headMarketing);
 
      headSales.add(salesExecutive1);
      headSales.add(salesExecutive2);
 
      headMarketing.add(clerk1);
      headMarketing.add(clerk2);
 
      //print all employees of the organization
      System.out.println(CEO); 
 
      for (Employee headEmployee : CEO.getSubordinates()) {
         System.out.println(headEmployee);
 
         for (Employee employee : headEmployee.getSubordinates()) {
            System.out.println(employee);
         }
      }		
   }
}

Rezultatul executiei: 

Employee :[ Name : John, dept : CEO, salary :30000 ]
Employee :[ Name : Robert, dept : Head Sales, salary :20000 ]
Employee :[ Name : Richard, dept : Sales, salary :10000 ]
Employee :[ Name : Rob, dept : Sales, salary :10000 ]
Employee :[ Name : Michel, dept : Head Marketing, salary :20000 ]
Employee :[ Name : Laura, dept : Marketing, salary :10000 ]
Employee :[ Name : Bob, dept : Marketing, salary :10000 ]

Referinte