Reputation: 13
Java Overriding method issues
I am working on an assignment "Dessert Shoppe" and basically what I need to do is to create DessertItem subclasses Candy, Cookie, IceCream, Sundae and Checkout. I am also provided with DessertItem class & DessertShoppe and I am not allowed to modify them.
While I have created all these subclasses, when I run it on my TestCheckout.java , it will not work but rather display getName() in Sundae cannot override getName() in DessertItem.
public final String getName(){
^
overriden method is final.
I will provide you guys all the classes that I have made now.
public class DessertShoppe {
public final static double TAX_RATE = 6.5; // 6.5%
public final static String STORE_NAME = "M & M Dessert Shoppe";
public final static int MAX_ITEM_NAME_SIZE = 25;
public final static int COST_WIDTH = 6;
public static String cents2dollarsAndCents(int cents) {
String s = "";
if (cents < 0) {
s += "-";
cents *= -1;
}
int dollars = cents/100;
cents = cents % 100;
if (dollars > 0)
s += dollars;
s +=".";
if (cents < 10)
s += "0";
s += cents;
return s;
}
}
public abstract class DessertItem {
protected String name;
public DessertItem() {
this("");
}
public DessertItem(String name) {
if (name.length() <= DessertShoppe.MAX_ITEM_NAME_SIZE)
this.name = name;
else
this.name = name.substring(0,DessertShoppe.MAX_ITEM_NAME_SIZE);
}
public final String getName() {
return name;
}
public abstract int getCost();
}
public class Cookie extends DessertItem{
protected double number;
protected double pricePerDoze;
public Cookie(String _n, double _ppd, int _number){
super(_n);
pricePerDoze = _ppd;
number = _number;
}
public int getCost(){
return (int)Math.round(number / 12 * pricePerDoze);
}
}
public class Candy extends DessertItem{
protected double weight;
protected double pricePerPound;
public Candy(String _n, double _ppp, int _w){
//using parent's constructor with name while storing its own properties
super(_n);
pricePerPound = _ppp;
weight = _w;
}
public int getCost(){
return (int)Math.round(weight * pricePerPound);
}
}
public class IceCream extends DessertItem{
protected int cost;
public IceCream(String _n, int _cost){
super(_n);
cost = _cost;
}
public int getCost(){
return cost;
}
}
public class Sundae extends IceCream{
protected String topName;
protected int topCost;
public Sundae(String _n0, int _cost0, String _n1, int _cost1){
//put the icecream name in icecream while putting top name and cost in a separate property
super(_n0, _cost0);
topName = _n1;
topCost = _cost1;
}
public final String getName(){
//return both the icecream name and the topping name
return name + " " + topName;
}
public int getCost(){
//return the sum of the icecream and the topping
return cost + topCost;
}
}
public class Checkout{
protected int size;
protected DessertItem[] dessertItems;
protected int amount;
protected int sum;
protected final double taxRate;
Checkout(){
size = 100;
dessertItems = new DessertItem[size];
amount = 0;
sum = 0;
taxRate = DessertShoppe.TAX_RATE;
}
public void enterItem(DessertItem d){
dessertItems[amount] = d;
amount ++;
}
public int numberOfItems(){
return amount;
}
public int totalCost(){
//make sum into zero, and calculate price from every item
sum = 0;
for(int i = 0; i < amount; i ++){
sum += dessertItems[i].getCost();
}
return sum;
}
public int totalTax(){
//use the totalCost method
return (int)(Math.round(this.totalCost() * taxRate / 100));
}
public void clear(){
//clear the array
for(DessertItem d : dessertItems){
d = null;
}
amount = 0;
sum = 0;
}
public String toString(){
String result = "Thank You! \n";
result += DessertShoppe.STORE_NAME + "\n";
result += "Purchased: ";
String totalPay = DessertShoppe.cents2dollarsAndCents( totalCost()+totalTax() );
if(totalPay.length() > DessertShoppe.COST_WIDTH){
totalPay = totalPay.substring(0, DessertShoppe.COST_WIDTH);
}
result += "$" + totalPay;
return result;
}
}
public class TestCheckout {
public static void main(String[] args) {
Checkout checkout = new Checkout();
checkout.enterItem(new Candy("Peanut Butter Fudge", 2.25, 399));
checkout.enterItem(new IceCream("Vanilla Ice Cream",105));
checkout.enterItem(new Sundae("Choc. Chip Ice Cream",145, "Hot Fudge", 50));
checkout.enterItem(new Cookie("Oatmeal Raisin Cookies", 4, 399));
System.out.println("\nNumber of items: " + checkout.numberOfItems() + "\n");
System.out.println("\nTotal cost: " + checkout.totalCost() + "\n");
System.out.println("\nTotal tax: " + checkout.totalTax() + "\n");
System.out.println("\nCost + Tax: " + (checkout.totalCost() + checkout.totalTax()) + "\n");
System.out.println(checkout);
checkout.clear();
checkout.enterItem(new IceCream("Strawberry Ice Cream",145));
checkout.enterItem(new Sundae("Vanilla Ice Cream",105, "Caramel", 50));
checkout.enterItem(new Candy("Gummy Worms", 1.33, 89));
checkout.enterItem(new Cookie("Chocolate Chip Cookies", 4, 399));
checkout.enterItem(new Candy("Salt Water Taffy", 1.5, 209));
checkout.enterItem(new Candy("Candy Corn",3.0, 109));
System.out.println("\nNumber of items: " + checkout.numberOfItems() + "\n");
System.out.println("\nTotal cost: " + checkout.totalCost() + "\n");
System.out.println("\nTotal tax: " + checkout.totalTax() + "\n");
System.out.println("\nCost + Tax: " + (checkout.totalCost() + checkout.totalTax()) + "\n");
System.out.println(checkout);
}
}
The expected output should be:
Number of items: 4
Total cost: 1331
Total tax: 87
Cost + Tax: 1418
M & M Dessert Shoppe
--------------------
2.25 lbs. @ 3.99 /lb.
Peanut Butter Fudge 8.98
Vanilla Ice Cream 1.05
Hot Fudge Sundae with
Choc. Chip Ice Cream 1.95
4 @ 3.99 /dz.
Oatmeal Raisin Cookies 1.33
Tax .87
Total Cost 14.18
Number of items: 6
Upvotes: 1
Views: 1816
Answers (2)
Reputation: 11832
When a method is marked as final, it means that it cannot be overridden in a subclass.
Therefore, you need to use the getName() method as it stands, and figure out how to get the appropriate value into the name variable.
Luckily, there's a constructor in IceCream that does that, so all you need to do is pass into the constructor what you want getName() to return (and what you want getCost() to return):
public Sundae(String _n0, int _cost0, String _n1, int _cost1){
super(_n1 + " Sundae with\n" + _n0, _cost0 + _cost1);
}
This way, your Sundae class doesn't need a getName() or a getCost() method.
Upvotes: 2
Reputation: 724
As stated in other answers, the final modifier means that the method cannot be overridden by any of its subclasses.
There are two ways around this:
The first is to pass the arguments into the Sundae constructor as shown by Jason:
super(_n0 + " " + _n1, _cost0 + _cost1);
The second would be to utilize the fact that Sundae is a subclass of IceCream, which is a subclass of DessertItem. The name field is protected, meaning that you could directly access the field from the constructor.
Keep in mind, that with the second option, you will need to explicitly check to make sure that the name you provide is shorter than DessertShoppe.MAX_ITEM_NAME_SIZE to keep in line with that standard length.
The simpler and probably intended solution would be the first one, though both are valid.
Upvotes: 0