Object-Oriented Programming: Polymorphism and Interfaces - Java: How to Program Early Objects - page 411

68
69 // 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());
}

70

71

72

73

74

75

76

77

} // end class HourlyEmployee

Fig. 10.6 | HourlyEmployee class extends Employee . (Part 3 of 3.)

10.5.4 Concrete Subclass CommissionEmployee
Class CommissionEmployee (Fig. 10.7) extends class Employee (line 4). The class includes a
constructor (lines 10-25) that takes a first name, a last name, a social security number, a sales
amount and a commission rate; set methods (lines 28-34 and 43-50) to assign valid new val-
ues to instance variables commissionRate and grossSales , respectively; get methods (lines
37-40 and 53-56) that retrieve the values of these instance variables; method earnings
(lines 59-63) to calculate a CommissionEmployee 's earnings; and method toString (lines
66-73), which returns the employee's type, namely, "commission employee: " and employ-
ee-specific information. The constructor also passes the first name, last name and social se-
curity number to superclass Employee 's constructor (line 14) to initialize Employee 's private
instance variables. Method toString calls superclass method toString (line 70) to obtain the
Employee -specific information (i.e., first name, last name and social security number).

1 // Fig. 10.7: CommissionEmployee.java

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 // constructor

10 public CommissionEmployee(String firstName, String lastName,

11 String socialSecurityNumber, double grossSales,

12 double commissionRate)

13 {

14 super (firstName, lastName, socialSecurityNumber);

15
16 if (commissionRate <= 0.0 || commissionRate >= 1.0 ) // validate

17 throw new IllegalArgumentException(

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

19
20 if (grossSales < 0.0 ) // validate

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

22

Fig. 10.7 | CommissionEmployee class extends Employee . (Part 1 of 2.)