public class CommissionEmployee extends Object {
    private final String firstName;
    private final String lastName;
    private final String socialSecurityNumber;
    private double grossSales; // gross weekly sales
    private double commissionRate; // commission percentage
}



public CommissionEmployee(String firstName, String lastName,
                          String socialSecurityNumber, double grossSales,
                          double commissionRate) {
                            
    if (grossSales < 0.0) {
        throw new IllegalArgumentException("Gross sales must be >= 0.0");
    }

    if (commissionRate <= 0.0 || commissionRate >= 1.0) {
        throw new IllegalArgumentException(
            "Commission rate must be > 0.0 and < 1.0");
    }

    this.firstName = firstName;
    this.lastName = lastName;
    this.socialSecurityNumber = socialSecurityNumber;
    this.grossSales = grossSales;
    this.commissionRate = commissionRate;
}

// 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; }

// set gross sales amount
public void setGrossSales(double grossSales) {
    if (grossSales < 0.0) {
        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) {
        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
public double earnings() { return commissionRate * grossSales; }

// return String representation of CommissionEmployee object
@Override // indicates that this method overrides a superclass method
public String toString() {
    return String.format("%s: %s %s%n%s: %s%n%s: %.2f%n%s: %.2f",
        "commission employee", firstName, lastName,
        "social security number", socialSecurityNumber,
        "gross sales", grossSales,
        "commission rate", commissionRate);
}






// Fig. 9.5: CommissionEmployeeTest.java
// CommissionEmployee class test program.
public class CommissionEmployeeTest {
    public static void main(String[] args) {
        // instantiate CommissionEmployee object
        CommissionEmployee employee = new CommissionEmployee(
            "Sue", "Jones", "222-22-2222", 10000, .06);

        // get commission employee data
        System.out.println("Employee information obtained by get methods:");
        System.out.printf("%n%s %s%n", "First name is", employee.getFirstName());
        System.out.printf("%s %s%n", "Last name is", employee.getLastName());
        System.out.printf("%s %s%n", "Social security number is", employee.getSocialSecurityNumber());
        System.out.printf("%s %.2f%n", "Gross sales is", employee.getGrossSales());
        System.out.printf("%s %.2f%n", "Commission rate is", employee.getCommissionRate());
    }
}

employee.setGrossSales(5000);
employee.setCommissionRate(.1);

System.out.printf("%n%s:%n%n%s%n",
    "Updated employee information obtained by toString", employee);