Hi I am supposed to modify class employee to implement interface Payable(another class) and declare method getPaymentAmount to invoke method earnings. Method getPaymentAmount would then be inherited by the subclasses in the Employee hierarchy. When getPaymentAmount is called for a particular subclass object, it polymorphically invokes the appropriate earnings method for that subclass. So far I have three errors in the Employee subclasses HourlyEmplyee, CommissionEmployee or BasePlusCommissionEmployee. The key Idea is to correct this errors without necessarily working on the classes themselves but by modifying class employee. Could anyone please help I have no idea on how to go on with the project. I have attached the whole project if you need to reference the other classes. {s/n JAVA RULES!!}
// Fig. 10.4: Employee.java
// Employee abstract superclass.
public abstract class Employee
{
private String firstName;
private String lastName;
private String socialSecurityNumber;
// three-argument constructor
public Employee( String first, String last, String ssn )
{
firstName = first;
lastName = last;
socialSecurityNumber = ssn;
} // end three-argument Employee constructor
// set first name
public void setFirstName( String first )
{
firstName = first; // should validate
} // end method setFirstName
// return first name
public String getFirstName()
{
return firstName;
} // end method getFirstName
// set last name
public void setLastName( String last )
{
lastName = last; // should validate
} // end method setLastName
// return last name
public String getLastName()
{
return lastName;
} // end method getLastName
// set social security number
public void setSocialSecurityNumber( String ssn )
{
socialSecurityNumber = ssn; // should validate
} // end method setSocialSecurityNumber
// return social security number
public String getSocialSecurityNumber()
{
return socialSecurityNumber;
} // end method getSocialSecurityNumber
// return String representation of Employee object
@Override
public String toString()
{
return String.format( "%s %s\nsocial security number: %s",
getFirstName(), getLastName(), getSocialSecurityNumber() );
} // end method toString
// abstract method overridden by concrete subclasses
public abstract double earnings(); // no implementation here
} // end abstract class Employee
