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.

You only need to submit one file, the PieceWorker class.

here are the codes

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// Fig. 10.8: BasePlusCommissionEmployee.java

// BasePlusCommissionEmployee class extends CommissionEmployee.

public class BasePlusCommissionEmployee extends CommissionEmployee {

private double baseSalary; // base salary per week

// constructor

public BasePlusCommissionEmployee(String firstName, String lastName,

String socialSecurityNumber, double grossSales,

double commissionRate, double baseSalary) {

super(firstName, lastName, socialSecurityNumber,

grossSales, commissionRate);

if (baseSalary < 0.0) { // validate baseSalary

throw new IllegalArgumentException("Base salary must be >= 0.0");

}

this.baseSalary = baseSalary;

}

// set base salary

public void setBaseSalary(double baseSalary) {

if (baseSalary < 0.0) { // validate baseSalary

throw new IllegalArgumentException("Base salary must be >= 0.0");

}

this.baseSalary = baseSalary;

}

// return base salary

public double getBaseSalary() {

return baseSalary;

}

// calculate earnings; override method earnings in CommissionEmployee

@Override

public double earnings() {

return getBaseSalary() + super.earnings();

}

// return String representation of BasePlusCommissionEmployee object

@Override

public String toString() {

return String.format("%s %s; %s: $%,.2f",

"base-salaried", super.toString(),

"base salary", getBaseSalary());

}

}

*********************************************************************************

// Fig. 10.7: CommissionEmployee.java

// CommissionEmployee class extends Employee.

public class CommissionEmployee extends Employee {

private double grossSales; // gross weekly sales

private double commissionRate; // commission percentage

// constructor

public CommissionEmployee(String firstName, String lastName,

String socialSecurityNumber, double grossSales,

double commissionRate) {

super(firstName, lastName, socialSecurityNumber);

if (commissionRate <= 0.0 || commissionRate >= 1.0) { // validate

throw new IllegalArgumentException(

"Commission rate must be > 0.0 and < 1.0");

}

if (grossSales < 0.0) { // validate

throw new IllegalArgumentException("Gross sales must be >= 0.0");

}

this.grossSales = grossSales;

this.commissionRate = commissionRate;

}

// set gross sales amount

public void setGrossSales(double grossSales) {

if (grossSales < 0.0) { // validate

throw new IllegalArgumentException("Gross sales must be >= 0.0");

}

this.grossSales = grossSales;

}

// return gross sales amount

public double getGrossSales() {

return grossSales;

}

// set commission rate

public void setCommissionRate(double commissionRate) {

if (commissionRate <= 0.0 || commissionRate >= 1.0) { // validate

throw new IllegalArgumentException(

"Commission rate must be > 0.0 and < 1.0");

}

this.commissionRate = commissionRate;

}

// return commission rate

public double getCommissionRate() {

return commissionRate;

}

// calculate earnings; override abstract method earnings in Employee

@Override

public double earnings() {

return getCommissionRate() * getGrossSales();

}

// return String representation of CommissionEmployee object

@Override

public String toString() {

return String.format("%s: %s%n%s: $%,.2f; %s: %.2f",

"commission employee", super.toString(),

"gross sales", getGrossSales(),

"commission rate", getCommissionRate());

}

}

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// Fig. 10.4: Employee.java

// Employee abstract superclass.

public abstract class Employee {

private final String firstName;

private final String lastName;

private final String socialSecurityNumber;

// constructor

public Employee(String firstName, String lastName,

String socialSecurityNumber) {

this.firstName = firstName;

this.lastName = lastName;

this.socialSecurityNumber = socialSecurityNumber;

}

// return first name

public String getFirstName() {

return firstName;

}

// return last name

public String getLastName() {

return lastName;

}

// return social security number

public String getSocialSecurityNumber() {

return socialSecurityNumber;

}

// return String representation of Employee object

@Override

public String toString() {

return String.format("%s %s%nsocial security number: %s",

getFirstName(), getLastName(), getSocialSecurityNumber());

}

// abstract method must be overridden by concrete subclasses

public abstract double earnings(); // no implementation here

}

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// Fig. 10.6: HourlyEmployee.java

// HourlyEmployee class extends Employee.

public class HourlyEmployee extends Employee {

private double wage; // wage per hour

private double hours; // hours worked for week

// constructor

public HourlyEmployee(String firstName, String lastName,

String socialSecurityNumber, double wage, double hours) {

super(firstName, lastName, socialSecurityNumber);

if (wage < 0.0) { // validate wage

throw new IllegalArgumentException(

"Hourly wage must be >= 0.0");

}

if ((hours < 0.0) || (hours > 168.0)) { // validate hours

throw new IllegalArgumentException(

"Hours worked must be >= 0.0 and <= 168.0");

}

this.wage = wage;

this.hours = hours;

}

// set wage

public void setWage(double wage) {

if (wage < 0.0) { // validate wage

throw new IllegalArgumentException(

"Hourly wage must be >= 0.0");

}

this.wage = wage;

}

// return wage

public double getWage() {

return wage;

}

// set hours worked

public void setHours(double hours) {

if ((hours < 0.0) || (hours > 168.0)) { // validate hours

throw new IllegalArgumentException(

"Hours worked must be >= 0.0 and <= 168.0");

}

this.hours = hours;

}

// return hours worked

public double getHours() {

return hours;

}

// calculate earnings; override abstract method earnings in Employee

@Override

public double earnings() {

if (getHours() <= 40) { // no overtime

return getWage() * getHours();

}

else {

return 40 * getWage() + (getHours() - 40) * getWage() * 1.5;

}

}

// return String representation of HourlyEmployee object

@Override

public String toString() {

return String.format("hourly employee: %s%n%s: $%,.2f; %s: %,.2f",

super.toString(), "hourly wage", getWage(),

"hours worked", getHours());

}

}

******************************************************************

// Exercise 10.15 Solution: PayrollSystemTest.java

// Employee hierarchy test program.

public class PayrollSystemTest {

public static void main(String[] args) {

// create five-element Employee array

Employee[] employees = new Employee[5];

// initialize array with Employees

employees[0] = new SalariedEmployee(

"John", "Smith", "111-11-1111", 800.00);

employees[1] = new HourlyEmployee(

"Karen", "Price", "222-22-2222", 16.75, 40);

employees[2] = new CommissionEmployee(

"Sue", "Jones", "333-33-3333", 10000, .06);

employees[3] = new BasePlusCommissionEmployee(

"Bob", "Lewis", "444-44-4444", 5000, .04, 300);

employees[4] = new PieceWorker(

"Rick", "Bridges", "555-55-5555", 2.25, 400);

System.out.println("Employees processed polymorphically: ");

// generically process each element in array employees

for (Employee currentEmployee : employees) {

System.out.println(currentEmployee); // invokes toString

System.out.printf(

"earned $%,.2f ", currentEmployee.earnings());

}

}

}

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// Fig. 10.5: SalariedEmployee.java

// SalariedEmployee concrete class extends abstract class Employee.

public class SalariedEmployee extends Employee {

private double weeklySalary;

// constructor

public SalariedEmployee(String firstName, String lastName,

String socialSecurityNumber, double weeklySalary) {

super(firstName, lastName, socialSecurityNumber);

if (weeklySalary < 0.0) {

throw new IllegalArgumentException(

"Weekly salary must be >= 0.0");

}

this.weeklySalary = weeklySalary;

}

// set salary

public void setWeeklySalary(double weeklySalary) {

if (weeklySalary < 0.0) {

throw new IllegalArgumentException(

"Weekly salary must be >= 0.0");

}

this.weeklySalary = weeklySalary;

}

// return salary

public double getWeeklySalary() {

return weeklySalary;

}

// calculate earnings; override abstract method earnings in Employee

@Override

public double earnings() {

return getWeeklySalary();

}

// return String representation of SalariedEmployee object

@Override

public String toString() {

return String.format("salaried employee: %s%n%s: $%,.2f",

super.toString(), "weekly salary", getWeeklySalary());

}

}