Problem with abstract methods

[jon ladd]

Its giveing me these errors "Class Employee should be declared abstract; it does not define method fullname() in class Employee at line 128"
andClass Customer should be declared abstract; it does not define method fullname() in class Customer at line 161. There not suppose to be abstrac just the Person class is.

  import java.util.*;
public class App {
  // The main entry point for the application.
  public static void main(String[] args) {
    // Variable for holding the number of orders.
    // Constant specifying the maximum number of persons
    // Variable for holding the user's menu choice.
    byte choice = 0;
    // Constants used as case selectors. Each of these corresponds to a menu
    // choice available to the user.
    final byte ADD_CUSTOMER = 1;
    final byte ADD_EMPLOYEE = 2;
    final byte BILLABLE_PERSONS = 3;
    final byte SHOW_CUSTOMERS = 4;
    final byte SHOW_EMPLOYEE = 5;
    final byte SHOW_ALL_PERSONS = 6;
    final byte EXIT = 7;
    // Array of superclass object references. Each element can be used to point
    // to subclass objects.
    Vector Person = new Vector();
    // THE MAIN PROCESSING LOOP of the program. It handles the processing of a
    // single user menu response and is repeated until the user wants to exit.
    while (choice != EXIT) {
      // Display the menu, read the user's response, and draw a separator
      // before processing their request.
      Utility.separator(80, '/');
      System.out.println("FAST FOOD MENU");
      Utility.skip();
      System.out.println("  1  Add a Customer");
      System.out.println("  2  Add an employee");
      System.out.println("  3  Show all billable persons");
      System.out.println("  4  Show all customers");
      System.out.println("  5  Show all employees");
      System.out.println("  6  Show all persons");
      System.out.println("  7  Exit");
      Utility.skip();
      System.out.print("Enter menu choice: ");
      choice = Keyboard.readByte();
      Utility.separator(80, '/');
      // This switch statement is used to direct the logic flow based upon
      // the user's menu selection.
      switch (choice) {
        case ADD_CUSTOMER:
          // Break out of the switch.
          break;
        case ADD_EMPLOYEE:
        case BILLABLE_PERSONS:
        case SHOW_CUSTOMERS:
        case SHOW_EMPLOYEE:
        case SHOW_ALL_PERSONS:
        case EXIT:
          break;
          // This is the default case. We get here when the user enters a menu
          // choice that doesn't match any of the above cases.
        default:
          // Display an error message indicating the user made an invalid
          // menu selection and break out of the switch.
          System.out.println("\t" + "Invalid menu choice - try again");
          break;
      }
    }
  }
}
abstract class Person {
  // Private instance variables for order number and amount due.
  private String firstname;
  private String lastname;
  // This constructor accepts one parameter - the order number. It uses the
  // value to initialize the order number and sets the amount due to zero.
  public Person(String iFirstName, String iLastName) {
    firstname = iFirstName;
    lastname = iLastName;
  }
  public void setFname(String newFname) {
    firstname = newFname;
  }
  public void setLname(String newLname) {
    lastname = newLname;
  }
  public String getFname() {
    return firstname;
  }
  public String getLname() {
    return lastname;
  }
  public abstract void fullname();
}
class Employee extends Person {
  private double payrate;
  /* Add this constructor to the Employee class */
  public Employee(String iFirstName, String iLastName) {
    super(iFirstName, iLastName);
  }
  public void setPrate(double newPrate) {
    payrate = newPrate;
  }
  public double getPrate() {
    return payrate;
  }
  public abstract void fullname();
  //   return getLname() + ", " + getFname();
  // public String toString() {
  //  String result =  fullname() + ", " + getPrate() ;
  //  return result;
  public String toString() {
    //  return fullname () + " , " + getPrate();
  }
}
interface Billable {
  public void amountDue();
}
class Customer extends Person {
  private double customerbalance;
  public Customer(String iFirstName, String iLastName) {
    super(iFirstName, iLastName);
  }
  public void setCustbal(double newCustbal) {
    customerbalance = newCustbal;
  }
  public double getCustbal() {
    return customerbalance;
  }
  public abstract void fullname();
  //   return getLname() + ", " + getFname();
   //public void String toString() {
    // String result = fullname() + ", " +    
         getCustbal();
    // return result;
   }
 

[Michael Morris]

You have to provide an implementation for public abstract void fullname() in order for the Employee class to be concrete (that is not abstract). So do something like this in Employee:

    public void fullname() {
      // whatever this method does
    }

[ April 29, 2003: Message edited by: Michael Morris ]

[jon ladd]

I have this is on my employee class and my customer class.
public String toString() {
String result = fullname() + ", " + getPrate() ;
return result;
and it gives me this error 'void' type not allowed here at line 161

[Michael Morris]

The toString method does not provide a method body for fullname. Aparrantly the return type is also incorrectly declared in the Parent class. It should be public abstract String fullname(). In that case the method could be defined something like this in the Employee class:

    public String fullname() {
        String fullName = getFname() + " " + getLname();
        return fullName;
    }

[ April 29, 2003: Message edited by: Michael Morris ]

[jon ladd]

were are u saying thats suppose to go?

[Layne Lund]

I don't think fullname() should even be abstract since every Person has full name, whether they are a Customer or an Employee. In other words, imho, the fullname() function that Michael gave should go in the Person class. If the Customer wants to do something different for its fullname() then Customer should have its own fullname() method that does the customizations necessary for a Customer.
HTH
Layne

[jon ladd]

were are u saying thats suppose to go?

[Angela Poynton]

I think you could really do with reading this it might help you out a bit.