Question

所以我仍然是Java新手，但对于作业，我需要

这是挑战13

互联网服务提供商 Internet服务提供商为其客户提供三种不同的订阅包：套餐A：每月9.95美元，提供10小时访问。额外的小时是每小时2.00美元。套餐B：每月13.95美元，提供20小时访问。额外的时间是每小时1.00美元。套餐C：每月19.95美元，提供无限制访问。编写一个计算客户月度账单的程序。它应该要求用户输入客户购买的包裹的字母* A，B或C）以及使用的小时数。然后它应显示总费用。

说明修改您为编程挑战13编写的程序

因此它还会计算并显示Package A客户的金额
，
将会节省
如果购买了套餐C，套餐B客户将保存。如果有
没有储蓄，不应打印任何信息。

所以这是我打印的代码：

package assignment14;

import java.util.*;

public class Assignment14
{
    public static void main(String[] args)
    {
        String userInput;

        char packageChosen;
        double packageA,packageB,totalHours, totalSavingsAtoB, totalSavingsAtoC, totalSavingsBtoC; 
/*THE ERROR MESSAGE OCCURS IN  THIS LINE FOR THE FIRST packageA AND FOR packageB*/   

        totalSavingsAtoB = (packageA - 13.95);
        totalSavingsAtoC = (packageA - 19.95);
        totalSavingsBtoC = (packageB - 19.95);

        Scanner keyboard = new Scanner(System.in);
        System.out.println("Which package have you obtain? (Please use A, B, or C)");
        userInput = keyboard.nextLine();
        packageChosen = userInput.charAt(0);


        switch (packageChosen)
        {

            case 'A': 
                System.out.println("What are the total amount of hours used for this month?");
                totalHours = keyboard.nextDouble();
                    if (totalHours <= 10)
                    {
                     packageA = 9.95 * totalHours;
                     System.out.print("For Package A:\nThe total charges for this month is $ " + packageA);
                     System.out.print("\nYou save a total of " + totalSavingsAtoB + "if you chose Package B\n" 
                                     + "and you would have save a total of " + totalSavingsAtoC + "if you chose Package C.");
                    }
                    else

                      packageA = 9.95 + (totalHours * 2.00);
                      System.out.print("For Package A:\nThe total charges for this month is $ " + packageA);

                    if (totalSavingsAtoB > packageA)
                    {
                        totalSavingsAtoB = (packageA - 13.95);
                        totalSavingsAtoC = (packageA - 19.95);
                        System.out.print("\nYou save a total of " + totalSavingsAtoB + "if you chose Package B\n" 
                                     + "and you would have save a total of " + totalSavingsAtoC + "if you chose Package C.");

                    }
                    break;
            case 'B': 
                System.out.println("What are the total amount of hours used for this month?");
                totalHours = keyboard.nextDouble();
                if (totalHours <= 20)
                {
                    packageB = 13.95 * totalHours;
                    System.out.print("For Package B:\nThe total charges for this month is $" + packageB);
                    System.out.print("You would have save a total of " + totalSavingsBtoC + ", if you have chosen Package C.");
                }
                else
                {
                    packageB = 13.95 + (totalHours * 1.00);
                    System.out.print("For Package B:\nThe total charges for this month is $" + packageB);
                    System.out.print("You would have save a total of " + totalSavingsBtoC + ", if you have chosen Package C.");
                }
                if (totalSavingsAtoB > packageA)
                {
                    totalSavingsBtoC = (packageB - 19.95);
                    System.out.print("\nYou save a total of " + totalSavingsAtoB + "if you chose Package B\n" 
                                     + "and you would have save a total of " + totalSavingsAtoC + "if you chose Package C.");

                }
                break;
            case 'C':
                System.out.print("For Package C:\nThe total charge for this is $19.95.");
                System.out.print(" \nThank you for using our service!  " );   
                     break;
            default:
                    System.out.print("Invalid entry, Please try again.");
       }

    }
}

我一直为packageA和packageB获取的错误消息是这些变量可能尚未初始化。

Answer 1

在初始化之前使用变量时会发生此错误（就像它说的那样）。编译器未为本地变量（例如您的packageA或packageB）分配默认值。

换句话说，它的抱怨是因为它不知道你在行totalSavingsAtoB = (packageA - 13.95)（以及其他行）中从中减去13.95。

所以，你需要在使用它们之前将packageA和packageB设置为某个值（可能是0？也许是包的成本是多少？我不知道。）

<强>除了

根据上下文我会猜测那些给你带来麻烦的3行应该在你设置值后去某个地方（我注意到你在交换机的每种情况下分配它们）。

Java代码：可能尚未初始化变量packageA和packageB。请帮忙

1 个答案: