我正在完成作业“Dessert Shoppe”，基本上我需要做的是创建DessertItem子类Candy，Cookie，IceCream，Sundae和{ {1}}。我也提供了DessertItem类＆amp; DessertShoppe和我不允许修改它们。
虽然我已经创建了所有这些子类，但是当我在TestCheckout.java上运行它时，它将无法工作，而是在Sundae中显示getName（）不能覆盖DessertItem中的getName（）。
Checkout我会为你们提供我现在所做的所有课程。
public final String getName(){
^
overriden method is final.
预期输出应为：
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);
}
}
答案 0 :(得分：2)
当方法被标记为final时，意味着它不能在子类中重写。
因此，您需要使用getName()方法，并弄清楚如何在name变量中获取适当的值。
幸运的是，IceCream中有一个构造函数可以执行此操作，因此您需要做的就是将您希望getName()返回的构造函数（以及您想要的getCost()）传递给构造函数返程）：
public Sundae(String _n0, int _cost0, String _n1, int _cost1){
super(_n1 + " Sundae with\n" + _n0, _cost0 + _cost1);
}
这样，您的圣代课程不需要getName()或getCost()方法。
答案 1 :(得分：0)
如其他答案中所述，final修饰符意味着该方法不能被其任何子类覆盖。
有两种解决方法：
第一种是将参数传递给Sundae构造函数，如Jason所示：
super(_n0 + " " + _n1, _cost0 + _cost1);
第二种方法是利用Sundae是IceCream的子类，这是DessertItem的子类。 name字段为protected，表示您可以直接从构造函数访问该字段。
请注意，使用第二个选项时，您需要明确检查以确保您提供的name短于DessertShoppe.MAX_ITEM_NAME_SIZE以保持与标准长度一致。
更简单且可能是预期的解决方案将是第一个，尽管两者都是有效的。