A company pays its employees on a weekly basis. The employees are of four types: Salaried employees are paid a fixed weekly salary regardless of the number of hours worked, hourly employees are paid by the hour and receive overtime pay for all hours worked in excess of 40 hours, commission employees are paid a percentage of their sales and salaried-commission employees receive a base salary plus a percentage of their sales. For the current pay period, the company has decided to reward salaried-commission employees by adding 10% to their base salaries. The company wants to implement a Java application that performs its payroll calculations polymorphically.
The polymorphic interfaces for the base class Employee has been listed in the Polymorphic Interface for Employee hierarchy table. The class definition of all the classes except for the BasePlusCommisionEmployee has been given. You are required to design the BasePlusCommissionEmployee indirect concrete subclass and write a driver program to test your overall implementation. Output of a sample test run is shown.
Note: You are required to use the polymorphic properties of the inheritance hierarchy.


Employee hierarchy class diagram


Polymorphic Interface for the Employee hierarchy

1 //Employee.java
2 // Employee abstract superclass.
3
4 public abstract class Employee
5 {
6 private String firstName;
7 private String lastName;
8 private String socialSecurityNumber;
9
10 // three-argument constructor
11 public Employee( String first, String last, String ssn )
12 {
13 firstName = first;
14 lastName = last;
15 socialSecurityNumber = ssn;
16 } // end three-argument Employee constructor
17
18 // set first name
19 public void setFirstName( String first )
20 {
21 firstName = first;
22 } // end method setFirstName
23
24 // return first name
25 public String getFirstName()
26 {
27 return firstName;
28 } // end method getFirstName
29
30 // set last name
31 public void setLastName( String last )
32 {
33 lastName = last;
34 } // end method setLastName
35
36 // return last name
37 public String getLastName()
38 {
39 return lastName;
40 } // end method getLastName
41
42 // set social security number
43 public void setSocialSecurityNumber( String ssn )
44 {
45 socialSecurityNumber = ssn; // should validate
46 } // end method setSocialSecurityNumber
47
48 // return social security number
49 public String getSocialSecurityNumber()
50 {
51 return socialSecurityNumber;
52 } // end method getSocialSecurityNumber
53
54 // return String representation of Employee object
55 public String toString()
56 {
57 return String.format( "%s %ssocial security number: %s",
58 getFirstName(), getLastName(), getSocialSecurityNumber() );
59 } // end method toString
60
61 // abstract method overridden by subclasses
62 public abstract double earnings(); // no implementation here
63 } // end abstract class Employee


1 // SalariedEmployee.java concrete sub-class derived from Employee
2 // SalariedEmployee class extends Employee.
3
4 public class SalariedEmployee extends Employee
5 {
6 private double weeklySalary;
7
8 // four-argument constructor
9 public SalariedEmployee( String first, String last, String ssn,
10 double salary )
11 {
12 super( first, last, ssn ); // pass to Employee constructor
13 setWeeklySalary( salary ); // validate and store salary
14 } // end four-argument SalariedEmployee constructor
15
16 // set salary
17 public void setWeeklySalary( double salary )
18 {
19 weeklySalary = salary < 0.0 ? 0.0 : salary;
20 } // end method setWeeklySalary
21
22 // return salary
23 public double getWeeklySalary()
24 {
25 return weeklySalary;
26 } // end method getWeeklySalary
27
28 // calculate earnings; override abstract method earnings in Employee
29 public double earnings()
30 {
31 return getWeeklySalary();
32 } // end method earnings
33
34 // return String representation of SalariedEmployee object
35 public String toString()
36 {
37 return String.format( "salaried employee: %s%s: $%,.2f",
38 super.toString(), "weekly salary", getWeeklySalary() );
39 } // end method toString
40 } // end class SalariedEmployee

1 // HourlyEmployee.java concrete sub-class derived from Employee
2 // HourlyEmployee class extends Employee.
3
4 public class HourlyEmployee extends Employee
5 {
6 private double wage; // wage per hour
7 private double hours; // hours worked for week
8
9 // five-argument constructor
10 public HourlyEmployee( String first, String last, String ssn,
11 double hourlyWage, double hoursWorked )
12 {
13 super( first, last, ssn );
14 setWage( hourlyWage ); // validate hourly wage
15 setHours( hoursWorked ); // validate hours worked
16 } // end five-argument HourlyEmployee constructor
17
18 // set wage
19 public void setWage( double hourlyWage )
20 {
21 wage = ( hourlyWage < 0.0 ) ? 0.0 : hourlyWage;
22 } // end method setWage
23
24 // return wage
25 public double getWage()
26 {
27 return wage;
28 } // end method getWage
29
30 // set hours worked
31 public void setHours( double hoursWorked )
32 {
33 hours = ( ( hoursWorked >= 0.0 ) && ( hoursWorked <= 168.0 ) ) ?
34 hoursWorked : 0.0;
35 } // end method setHours
36
37 // return hours worked
38 public double getHours()
39 {
40 return hours;
41 } // end method getHours
42
43 // calculate earnings; override abstract method earnings in Employee
44 public double earnings()
45 {
46 if ( getHours() <= 40 ) // no overtime
47 return getWage() * getHours();
48 else
49 return 40 * getWage() + ( gethours() - 40 ) * getWage() * 1.5;
50 } // end method earnings
51
52 // return String representation of HourlyEmployee object
53 public String toString()
54 {
55 return String.format( "hourly employee: %s%s: $%,.2f; %s: %,.2f",
56 super.toString(), "hourly wage", getWage(),
57 "hours worked", getHours() );
58 } // end method toString
59 } // end class HourlyEmployee



1 // CommissionEmployee.java concrete sub-class derived from Employee
2 // CommissionEmployee class extends Employee.
3
4 public class CommissionEmployee extends Employee
5 {
6 private double grossSales; // gross weekly sales
7 private double commissionRate; // commission percentage
8
9 // five-argument constructor
10 public CommissionEmployee( String first, String last, String ssn,
11 double sales, double rate )
12 {
13 super( first, last, ssn );
14 setGrossSales( sales );
15 setCommissionRate( rate );
16 } // end five-argument CommissionEmployee constructor
17
18 // set commission rate
19 public void setCommissionRate( double rate )
20 {
21 commissionRate = ( rate > 0.0 && rate < 1.0 ) ? rate : 0.0;
22 } // end method setCommissionRate
23
24 // return commission rate
25 public double getCommissionRate()
26 {
27 return commissionRate;
28 } // end method getCommissionRate
29
30 // set gross sales amount
31 public void setGrossSales( double sales )
32 {
33 grossSales = ( sales < 0.0 ) ? 0.0 : sales;
34 } // end method setGrossSales
35
36 // return gross sales amount
37 public double getGrossSales()
38 {
39 return grossSales;
40 } // end method getGrossSales
41
42 // calculate earnings; override abstract method earnings in Employee
43 public double earnings()
44 {
45 return getCommissionRate() * getGrossSales();
46 } // end method earnings
47
48 // return String representation of CommissionEmployee object
49 public String toString()
50 {
51 return String.format( "%s: %s%s: $%,.2f; %s: %.2f",
52 "commission employee", super.toString(),
53 "gross sales", getGrossSales(),
54 "commission rate", getCommissionRate() );
55 } // end method toString
56 } // end class CommissionEmployee

?

Output of a sample test run

Employees processed individually:

salaried employee: John Smith
social security number: 111-11-1111
weekly salary: $800.00
earned: $800.00

hourly employee: Karen Price
social security number: 222-22-2222
hourly wage: $16.75; hours worked: 40.00
earned: $670.00

commission employee: Sue Jones
social security number: 333-33-3333
gross sales: $10,000.00; commission rate: 0.06
earned: $600.00

base-salaried commission employee: Bob Lewis
social security number: 444-44-4444
gross sales: $5,000.00; commission rate: 0.04; base salary: $300.00
earned: $500.00

Employees processed polymorphically:

salaried employee: John Smith
social security number: 111-11-1111
weekly salary: $800.00
earned $800.00

hourly employee: Karen Price
social security number: 222-22-2222
hourly wage: $16.75; hours worked: 40.00
earned $670.00

commission employee: Sue Jones
social security number: 333-33-3333
gross sales: $10,000.00; commission rate: 0.06
earned $600.00

base-salaried commission employee: Bob Lewis
social security number: 444-44-4444
gross sales: $5,000.00; commission rate: 0.04; base salary: $300.00
new base salary with 10% increase is: $330.00
earned $530.00

Employee 0 is a SalariedEmployee
Employee 1 is a HourlyEmployee
Employee 2 is a CommissionEmployee
Employee 3 is a BasePlusCommissionEmployee