Lab 8

(Accounts Payable System Modification)

In this exercise, we modify the accounts payable application.

The application should still process two Invoice objects, but now should process one object of each of the four Employee subclasses. If the object currently being processed is a BasePlusCommissionEmployee, the application should increase the BasePlusCommissionEmployee’s base salary by 10%. Finally, the application should output the payment amount for each object.

Download the Lab 8 Program Template here and Complete the following steps to create the new application.

a) Modify classes HourlyEmployee and CommissionEmployee to place them in the Payable hierarchy as subclasses

of the version of Employee that implements Payable. [Hint: Change the name of method

earnings to getPaymentAmount in each subclass so that the class satisfies its inherited contract with interface

Payable.]

b) Modify class BasePlusCommissionEmployee such that it extends the version of class CommissionEmployee

created in Part a.

c) Modify PayableInterfaceTest to polymorphically process two Invoices, one SalariedEmployee, one

HourlyEmployee, one CommissionEmployee and one BasePlusCommissionEmployee. First output a string

representation of each Payable object. Next, if an object is a BasePlusCommissionEmployee, increase its base

salary by 10%. Finally, output the payment amount for each Payable object.