Chain Of Responsibility Design Pattern - Implementation

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Chain Of Responsibility Design Pattern - Implementation

Chain Of Responsibility Design Pattern - Implementation - Class Diagram

Employee.java

public abstract class Employee
{

// next element in chain or responsibility
protected Employee supervisor;

public void setNextSupervisor( Employee supervisor )
{
this.supervisor = supervisor;
}

public abstract void applyLeave( String employeeName, int numberofDaysLeave );
}

TeamLeader.java

public class TeamLeader extends Employee
{
// TeamLeader can only approve upto 10 days of leave
private int MAX_LEAVES_CAN_APPROVE = 10;

public void applyLeave( String employeeName, int numberofDaysLeave )
{
 // check if TeamLeader can process this request
if( numberofDaysLeave <= MAX_LEAVES_CAN_APPROVE )
{
ApproveLeave(employeeName, numberofDaysLeave);
}
 // if TeamLeader can't process the LeaveRequest then pass on to the supervisor(ProjectLeader)
             // so that he can process
else
{
supervisor.applyLeave(employeeName, numberofDaysLeave);
}
}

private void ApproveLeave( String employeeName, int numberofDaysLeave )
{
System.out.println("TeamLeader approved " + numberofDaysLeave + " days " + "Leave for the employee : "
                + employeeName);

}
}

ProjectLeader.java

public class ProjectLeader extends Employee

{

// ProjectLeader can only approve upto 20 days of leave

private int MAX_LEAVES_CAN_APPROVE = 20;

public void applyLeave( String employeeName, int numberofDaysLeave )

{

 // check if ProjectLeader can process this request

if( numberofDaysLeave <= MAX_LEAVES_CAN_APPROVE )

{

ApproveLeave(employeeName, numberofDaysLeave);

}

// if ProjectLeader can't process the LeaveRequest then pass on to the supervisor(HR) 

             // so that he can process

else

{

supervisor.applyLeave(employeeName, numberofDaysLeave);

}

}

private void ApproveLeave( String employeeName, int numberofDaysLeave )

{

System.out.println("ProjectLeader approved " + numberofDaysLeave + " days " + "Leave for the employee : "

                + employeeName);

}

}

HR.java

public class HR extends Employee

{

// HR can only approve upto 30 days of leave

private int MAX_LEAVES_CAN_APPROVE = 30;

public void applyLeave( String employeeName, int numberofDaysLeave )

{

if( numberofDaysLeave <= MAX_LEAVES_CAN_APPROVE )

{

ApproveLeave(employeeName, numberofDaysLeave);

}

else

{

System.out.println("Leave application suspended, Please contact HR");

}

}

private void ApproveLeave( String employeeName, int numberofDaysLeave )

{

System.out.println("HR approved " + numberofDaysLeave + " days " + "Leave for the employee : "

                + employeeName);

}

}

ChainPatternDemo.java

public class ChainPatternDemo

{

public static void main( String[] args )

{

TeamLeader teamLeader= new TeamLeader();

ProjectLeader projectLeader= new ProjectLeader();

HR hr=new HR();

teamLeader.setNextSupervisor(projectLeader);

projectLeader.setNextSupervisor(hr);

teamLeader.applyLeave("David", 9);

System.out.println();

teamLeader.applyLeave("John", 18);

System.out.println();

teamLeader.applyLeave("Steve", 30);

System.out.println();

teamLeader.applyLeave("Rohan", 50);

}

}

Output

TeamLeader approved 9 days Leave for the employee : David

ProjectLeader approved 18 days Leave for the employee : John

HR approved 30 days Leave for the employee : Steve

Leave application suspended, Please contact HR

See also:

Chain of Responsibility Design Pattern - Introduction

Chain of Responsibility Design Pattern - Real time Example

Chain of Responsibility Design Pattern - Class and Sequence Diagram

Chain of Responsibility Design Pattern - Implementation(one or more Receiver)

Chain of Responsibility Design Pattern - Key Points

All Design Patterns Links