Composite design Pattern

Composite Pattern

This pattern is used to create a tree structure. Suppose, we want to design a role hierarchies for an organization and say the hierarchy is as follows,

CEO

----- VPs

--------- Directors

---------------------- Managers

package com.exmpl.CompositePattern;

import java.util.ArrayList;

import java.util.List;

public class Employee {

       private String designation;

       private String empName;

       private String empId;

       private double empSalary;

       private List<Employee> listOfEmps;

       public Employee(final String empName, final String empId,

                     String designation, final double empSalary) {

              this.empName = empName;

              this.empId = empId;

              this.designation = designation;

              this.empSalary = empSalary;

              listOfEmps = new ArrayList<Employee>();

       }

       public void add(Employee emp) {

              listOfEmps.add(emp);

       }

       public List<Employee> getListOfEmps() {

              return listOfEmps;

       }

       @Override

       public String toString() {

              return "Employee [designation=" + designation + ", empName=" + empName

                           + ", empId=" + empId + ", empSalary=" + empSalary + "]";

       }

}
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package com.exmpl.CompositePattern;

public class CompositePatternExample {

       public static void main(String args[]) {

              // One CEO of an organization.

              Employee CEO = new Employee("Mr. Mark Walls", "EMP-0001", "CEO",

                           250000.00);

              // Suppose two VPs under CEO

              Employee VP_ONE = new Employee("Mr. Patric Anderson", "EMP-0002", "VP",

                           200000.00);

              Employee VP_TWO = new Employee("Mr. Sent Willam", "EMP-0003", "VP",

                           200000.00);

              // Suppose four Directors under VP

              Employee DR_ONE = new Employee("Ms. Ena Richard", "EMP-0002",

                           "Director", 150000.00);

              Employee DR_TWO = new Employee("Mr. Aaron Hank", "EMP-0003",

                           "Director", 150000.00);

              Employee DR_THREE = new Employee("Mr. Barker Clive", "EMP-0002",

                           "Director", 150000.00);

              Employee DR_FOUR = new Employee("Mr. Freud Sigmund", "EMP-0003",

                           "Director", 150000.00);

              // Suppose eight Manages under Director

              Employee MANAGER_ONE = new Employee("Mr. Freund Peter", "EMP-0002",

                           "Manager", 100000.00);

              Employee MANAGER_TWO = new Employee("Mr. Frostrup Mariella",

                           "EMP-0003", "Manager", 100000.00);

              Employee MANAGER_THREE = new Employee("Mr. Gephardt Dick", "EMP-0002",

                           "Manager", 100000.00);

              Employee MANAGER_FOUR = new Employee("Mr. Giacometti Alberto",

                           "EMP-0003", "Manager", 100000.00);

              Employee MANAGER_FIVE = new Employee("Ms. Foch Ferdinand", "EMP-0002",

                           "Manager", 100000.00);

              Employee MANAGER_SIX = new Employee("Mr. Hayek Friedrich", "EMP-0003",

                           "Manager", 100000.00);

              Employee MANAGER_SEVEN = new Employee("Mr. Hazlitt William",

                           "EMP-0002", "Manager", 100000.00);

              Employee MANAGER_EIGHT = new Employee("Mr. Louis Joe", "EMP-0003",

                           "Manager", 100000.00);

              // VPs under CEO

              CEO.add(VP_ONE);

              CEO.add(VP_TWO);

              // Directors under VP

              VP_ONE.add(DR_ONE);

              VP_ONE.add(DR_TWO);

              VP_TWO.add(DR_THREE);

              VP_TWO.add(DR_FOUR);

              // Managers under Director.

              DR_ONE.add(MANAGER_ONE);

              DR_ONE.add(MANAGER_TWO);

              DR_TWO.add(MANAGER_THREE);

              DR_TWO.add(MANAGER_FOUR);

              DR_THREE.add(MANAGER_FIVE);

              DR_THREE.add(MANAGER_SIX);

              DR_FOUR.add(MANAGER_SEVEN);

              DR_FOUR.add(MANAGER_EIGHT);

             

              //Print the Employee Tree.

              System.out.println(CEO);

              for(Employee vp : CEO.getListOfEmps() ){

                     System.out.println("-------->"+vp);

                     for(Employee director : vp.getListOfEmps()){

                           System.out.println("---------------->"+director);

                           for(Employee manager : director.getListOfEmps()){

                                   System.out.println("------------------------>"+manager);

                           }

                     }

              }

       }

}

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Output è

Employee [designation=CEO, empName=Mr. Mark Walls, empId=EMP-0001, empSalary=250000.0]

-------->Employee [designation=VP, empName=Mr. Patric Anderson, empId=EMP-0002, empSalary=200000.0]

---------------->Employee [designation=Director, empName=Ms. Ena Richard, empId=EMP-0002, empSalary=150000.0]

------------------------>Employee [designation=Manager, empName=Mr. Freund Peter, empId=EMP-0002, empSalary=100000.0]

------------------------>Employee [designation=Manager, empName=Mr. Frostrup Mariella, empId=EMP-0003, empSalary=100000.0]

---------------->Employee [designation=Director, empName=Mr. Aaron Hank, empId=EMP-0003, empSalary=150000.0]

------------------------>Employee [designation=Manager, empName=Mr. Gephardt Dick, empId=EMP-0002, empSalary=100000.0]

------------------------>Employee [designation=Manager, empName=Mr. Giacometti Alberto, empId=EMP-0003, empSalary=100000.0]

-------->Employee [designation=VP, empName=Mr. Sent Willam, empId=EMP-0003, empSalary=200000.0]

---------------->Employee [designation=Director, empName=Mr. Barker Clive, empId=EMP-0002, empSalary=150000.0]

------------------------>Employee [designation=Manager, empName=Ms. Foch Ferdinand, empId=EMP-0002, empSalary=100000.0]

------------------------>Employee [designation=Manager, empName=Mr. Hayek Friedrich, empId=EMP-0003, empSalary=100000.0]

---------------->Employee [designation=Director, empName=Mr. Freud Sigmund, empId=EMP-0003, empSalary=150000.0]

------------------------>Employee [designation=Manager, empName=Mr. Hazlitt William, empId=EMP-0002, empSalary=100000.0]

------------------------>Employee [designation=Manager, empName=Mr. Louis Joe, empId=EMP-0003, empSalary=100000.0]