In the book Java How to Program Early Objects, 10th edition in chapter 9, exerci

Question

In the book Java How to Program Early Objects, 10th edition in chapter 9, exercise 9.3 there is a solution but I need to come up with a solution that uses a six-argument constructor. (I think the current solution is using aggregation) I am having problems implementing this constructor. The constructor that is set up is // six-argument constructor
public BasePlusCommissionEmployeeComposition( String first, String last,
String ssn, double sales, double rate, double salary) {
  
   // TODO: implement this constructor

}

I need help on setting up the instance variables and completing the constructor.

Explanation / Answer

CommissionEmployee.java:

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

   // five-argument constructor
   public CommissionEmployee(String firstName, String lastName,
           String socialSecurityNumber, double grossSales,
           double commissionRate) {
       // implicit call to Object constructor occurs here

       // if grossSales is invalid throw exception
       if (grossSales < 0.0)
           throw new IllegalArgumentException("Gross sales must be >= 0.0");

       // if commissionRate is invalid throw exception
       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;
   }

   public String getFirstName() {
       return firstName;
   }

   public String getLastName() {
       return lastName;
   }

   public String getSocialSecurityNumber() {
       return socialSecurityNumber;
   }

   public double getGrossSales() {
       return grossSales;
   }

   public double getCommissionRate() {
       return commissionRate;
   }

   // 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;
   }

   // 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 String representation of CommissionEmployee object
   @Override
   public String toString() {
       return String.format("%s: %s %s%n%s: %s%n%s: %.2f%n%s: %.2f",
               "commission employee", getFirstName(), getLastName(),
               "social security number", getSocialSecurityNumber(),
               "gross sales", getGrossSales(), "commission rate",
               getCommissionRate());
   }

   // calculate earnings
   public double earnings() {
       return getCommissionRate() * getGrossSales();
   }
}

BasePlusCommissionEmployee.java:

public class BasePlusCommissionEmployee {

// instead of extending the class, we are keeping a private variable
private CommissionEmployee commissionEmployee;

   private double baseSalary;

   public BasePlusCommissionEmployee(String first, String last, String ssn,
           double sales, double rate, double salary) {
       commissionEmployee = new CommissionEmployee(first, last, ssn, sales, rate);

       if (baseSalary < 0.0) {
           throw new IllegalArgumentException("Base salary must be >= 0.0");
       }
      
       this.baseSalary = salary;
   }
}

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