Modify the payroll system of Figs. 10.4–10.9 to include an additional Employee subclass PieceWorker

Modify the payroll system of Figs. 10.4–10.9 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 employee’s 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 employee’s 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 (SalariedEmployee, CommissionEmployee, HourlyEmployee, BasePlusCommissionEmployee, and now PieceWorker).

For each Employee, display its String representation and earnings.

// 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 } // end abstract class Employee // 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()); } } // end class SalariedEmployee // 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 // 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 // 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()); } } // end class BasePlusCommissionEmployee / Fig. 10.9: PayrollSystemTest.java // Employee hierarchy test program. public class PayrollSystemTest { public static void main(String[] args) { // create subclass objects SalariedEmployee salariedEmployee = new SalariedEmployee("John", "Smith", "111-11-1111", 800.00); HourlyEmployee hourlyEmployee = new HourlyEmployee("Karen", "Price", "222-22-2222", 16.75, 40); CommissionEmployee commissionEmployee = new CommissionEmployee( "Sue", "Jones", "333-33-3333", 10000, .06); BasePlusCommissionEmployee basePlusCommissionEmployee = new BasePlusCommissionEmployee( "Bob", "Lewis", "444-44-4444", 5000, .04, 300); System.out.println("Employees processed individually:"); System.out.printf("%n%s%n%s: $%,.2f%n%n", salariedEmployee, "earned", salariedEmployee.earnings()); System.out.printf("%s%n%s: $%,.2f%n%n", hourlyEmployee, "earned", hourlyEmployee.earnings()); System.out.printf("%s%n%s: $%,.2f%n%n", commissionEmployee, "earned", commissionEmployee.earnings()); System.out.printf("%s%n%s: $%,.2f%n%n", basePlusCommissionEmployee, "earned", basePlusCommissionEmployee.earnings()); // create four-element Employee array Employee[] employees = new Employee[4]; // initialize array with Employees employees[0] = salariedEmployee; employees[1] = hourlyEmployee; employees[2] = commissionEmployee; employees[3] = basePlusCommissionEmployee; System.out.printf("Employees processed polymorphically:%n%n"); // generically process each element in array employees for (Employee currentEmployee : employees) { System.out.println(currentEmployee); // invokes toString // determine whether element is a BasePlusCommissionEmployee if (currentEmployee instanceof BasePlusCommissionEmployee) { // downcast Employee reference to // BasePlusCommissionEmployee reference BasePlusCommissionEmployee employee = (BasePlusCommissionEmployee) currentEmployee; employee.setBaseSalary(1.10 * employee.getBaseSalary()); System.out.printf( "new base salary with 10%% increase is: $%,.2f%n", employee.getBaseSalary()); } System.out.printf( "earned $%,.2f%n%n", currentEmployee.earnings()); } // get type name of each object in employees array for (int j = 0; j