Java project help

Download and import PayrollSystem.jar as a Java project into your Eclipse. Modify this payroll system to include an additional Employee subclass PieceWorker that represents an employee whose pay is based on the number of pieces of merchandise produced. Class PieceWorker should contain private instance variables wage (to store the employees wage per piece) and pieces (to store the number of pieces produced). Provide a concrete implementation of method earnings in class PieceWorker that calculates the employees earnings by multiplying the number of pieces produced by the wage per piece. Create an array of Employee variables to store references to objects of each concrete class in the new Employee hierarchy. For each Employee, display its String representation and earnings.

Link to the .jar file : https://www.dropbox.com/s/cn36xa5x636o8iz/PayrollSystem.jar?dl=0