Question

我只是大学一年级学生，我的项目正在创建一个订购系统，但我坚持定价，因为我不能正确地做总价。当程序循环时，它计算出错误的价格。 A1和A2是我输入的唯一选择，因为这仍然是一个未完成的项目。

import java.io.*;
public class Ordering_System
{
     public static void main(String []args) throws Exception
     {
         BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
         String order,again;
         int quantity,price1=0,price2=0,loop1=0,quantity1,quantity2=0;

         System.out.println("  ");  

         System.out.println("Welcome to MgRonalds, What do you want to order?");

         System.out.println(" ");
         System.out.println("*******************************************************************");
         System.out.println("*   Code    Meal             ''MENU''              Price          *");
         System.out.println("*                                                                 *");
         System.out.println("*   (A1)   MgBurger                                P30.00         *");
         System.out.println("*   (A2)   Big Mac                                 P139.00        *");
         System.out.println("*   (B1)   Cheese Burger                           P35.00         *");
         System.out.println("*   (B2)   Chicken Burger                          P50.00         *");
         System.out.println("*   (C1)   MgNuggets                               P65.00         *");
         System.out.println("*   (C2)   MgChicken                               P79.00         *");
         System.out.println("*   (D1)   MgSpagetti                              P60.00         *");
         System.out.println("*   (D2)   MgFries                                 P40.00         *");
         System.out.println("*   (E1)   Coke                                    P10.00         *");
         System.out.println("*   (E2)   Sprite                                  P10.00         *");
         System.out.println("*   (E3)   Royal                                   P10.00         *");
         System.out.println("*   (F1)   Sundae                                  P25.00         *");
         System.out.println("*   (F2)   MgFloat                                 P25.00         *");
         System.out.println("*                                                                 *");
         System.out.println("*******************************************************************");

         do{
            System.out.println("");
            System.out.print("Enter Code Order      : ");
            order=br.readLine();
            if (order.equalsIgnoreCase("A1")) {
                price1=30;
                System.out.println("Order Description     : MgBurger ");
            } else if (order.equalsIgnoreCase("A2")) {
                price1=139;
                System.out.println("Order Description     : Big Mac ");
            }   

            System.out.print("Enter Quantity        : ");
            quantity1= Integer.parseInt(br.readLine());
            quantity2=quantity1+quantity2;

            price2=price1*quantity2;   

            System.out.print("Another Order?  (Y/N) : ");
            again=br.readLine();
            if (again.equalsIgnoreCase("y"))
                loop1=loop1+1;
            else loop1=loop1-100;
      } while (loop1==1);    

     System.out.println(" ");
     System.out.println("Total Price           : "+price2);   

 }
}

以下是输出示例：

Enter Code Order      : a1
Order Description     : MgBurger 
Enter Quantity        : 2
Another Order?  (Y/N) : y

Enter Code Order      : a2
Order Description     : Big Mac 
Enter Quantity        : 2
Another Order?  (Y/N) : n

Total Price           : 556

答案应该是338而不是556

Answer 1

让我们逻辑地解决这个问题：

在第一次循环：

输入代码订单：a1

现在，price1 = 30

订单描述：MgBurger

输入数量：2

quantity1 = 2
quantity2 = quantity1 + quantity2 = 2 + 0 = 2;
price2 = 30 * 2 = 60;

同意？

另一个命令？（是/否）：y

在第二次循环上，我们仍然有price1=30，quantity1 = 2，quantity2 = 2和price2 = 60。现在：

输入代码订单：a2

price1 = 139

订单描述：巨无霸

输入数量：2

quantity1 = 2;
quantity2 = quantity1 + quantity2 = 2 + 2 = 4;
price2 = 139 * 4 = 556;

发现错误了吗？ quantity2仍然保留循环中前一个事务的值。

Answer 2

你干脆怎么样？添加变量total =0;

  System.out.print("Enter Quantity        : ");
  quantity1 = Integer.parseInt(br.readLine());
  // quantity2=quantity1+quantity2;

  // price2=price1*quantity2;

  total += price1 * quantity1;

  ...
  System.out.println(" ");
  System.out.println("Total Price           : " + total);

Answer 3

您可以按如下方式简化代码。还要考虑使用浮动值代替int。

public static void main(String[] args) throws Exception {
  System.out.println("  ");

  // Display the Menu

  BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
  String order, again;
  int quantity = 0;
  int total = 0;
  while (true) {
    System.out.println("");
    System.out.print("Enter Code Order      : ");
    order = br.readLine();
    System.out.print("Enter Quantity        : ");
    quantity = Integer.parseInt(br.readLine());

    total += getPrice(order) * quantity;

    System.out.print("Another Order?  (Y/N) : ");
    again = br.readLine();
    if (again.equalsIgnoreCase("N")) {
      break;
    }
  }

  System.out.println(" ");
  System.out.println("Total Price           : " + total);
}

private static int getPrice(String order) {
  int price = 0;
  // using switch-case would be more appropriate
  if (order.equalsIgnoreCase("A1")) {
    price = 30;
    System.out.println("Order Description     : MgBurger ");
  } else if (order.equalsIgnoreCase("A2")) {
    price = 139;
    System.out.println("Order Description     : Big Mac ");
  }
  return price;
}

如何计算Java订购系统的总价？

3 个答案: