Q : 执行多个循环和多个 if 语句和 if-else 语句 ||租车计算器项目

Question

我对该项目的说明如下：

说明：使用哨兵值循环。创建一个基本的租车计算器

询问每个用户：

车辆类型（可以使用字符串以外的其他内容，例如：1 代表经济型，2 代表轿车等） 租用天数 计算（针对每个客户）：

租金， 税收， 到期总额。 有三种不同的租金选择：经济 @ 31.76、轿车 @ 40.32、SUV @ 47.56。 [注意：只考虑全天单位（无小时费率）]。

销售税为 TOTAL 的 6%。

使用以下方法创建摘要数据：

客户数量 总收钱。 此外，还包括 IPO、算法和案头检查值（设计文档）。

{我要做什么和我的问题}

package tests;

import java.util.InputMismatchException;
import java.util.Scanner;

public class Tester {

public static void main(String []args){
int count=0;
int days;
int cus = 10; 
double DailyFee=0, NontaxTotal, CarType, Total,FullTotal=0;
boolean F1 = false, F2 = false, F3 = false;
Scanner in=new Scanner(System.in);


while (F3 == false) {
    F3 = true;
    System.out.print("Press 1 to enter Rental Calculator or else press 0 to quit\n");
    System.out.println("Please only enter 1 or 0. Also, please only enter number(s) not letter(s)");
    try {
        cus=in.nextInt();
        if (cus == 0 || cus == 1) {
            F3 = true;
        } else {
            F3 = false;
            System.out.println("Number must be either 1 or 0");
        }
    } catch (InputMismatchException ex) {
        F3 = false;
        System.out.println("Invalid entry");
        in.next();
    }
}

    if(cus == 1) { 
        while(F1 == false) {
            F1 = true;
            count++;
            System.out.print("What vehical would you like to rent?\n");
            System.out.println("Enter 1 for an economy car");
            System.out.println("Enter 2 for a sedan car");
            System.out.println("Enter 3 for an SUV");
            // 
            try {
                CarType = in.nextInt();
                if (CarType <= 0 || CarType >= 4) {
                    System.out.print("Number must be 1-3\n");
                    System.out.println("Please enter 1 for an economy car");
                    System.out.println("Enter 2 for a sedan car");
                    System.out.println("Enter 3 for an SUV");

                    F1 = false;
                } else {
                     if (CarType == 1) {
                         F1 = true;
                          DailyFee=31.76;
                } else if(CarType == 2) {
                        F1 = true;
                          DailyFee=40.32;
                } else if(CarType == 3) {
                        F1 = true;
                          DailyFee=47.56;
                }
                while (F2 == false) {
                    F2 = true;
                    try { 
                        System.out.print("Please enter the number of days rented. (Example; 3) : ");
                        days = in.nextInt();
                        if (days <= 0) {
                            System.out.println("Number of days must be more than zero");
                            F2 = false;
                        } else {

                            double x=days;
                            NontaxTotal = (DailyFee * x);
                            Total = (NontaxTotal * 1.06);
                            FullTotal+=Total;
                            F3 = true;

                        }
                    } catch(InputMismatchException ex) {
                        System.out.println("Answer must be a number");
                        F2 = false;
                        in.next();
                        }
                    }
                }
            } catch (InputMismatchException ex) {
                F1 = false;
                System.out.println("Answer must be a number"); 
            }
        }
    }
    in.close();
    System.out.println("Count of customers : " + count);
    System.out.printf("Total of the Day : $ %.2f", FullTotal);

    }
}

{我的问题}

1. 当在提示“按 1 进入租金计算器或按 0 退出”提示输入字母时，会显示错误提示，然后控制台要求再次输入。类似地，当在提示“您想租什么车辆？”时输入一个字母时。控制台继续不停地打印行？我不知道如何解决这个问题？

2. 我希望我的程序允许进行多个计算输入。但是，在完整的计算输入（天 * 税 * 汽车类型）之后，控制台发布汇总数据而不是循环？ 2a.在提示“请输入租用的天数。（示例；3）：”后，并跟随用户输入。我如何让我的程序循环回到询问“按 1 进入租金计算器或按 0 退出”？仍然使 0 提示我的摘要数据？

Answer 1

我刚刚“重构”了您的代码，删除了一些过时的代码并将一些其他代码放在其他位置。 我还对变量使用了更清晰的命名，并遵循了命名约定。

您遇到的问题是，您没有在每个 catch block 中都有一个 in.next();，这意味着在迭代时，该变量一直使用相同的变量（这是无效的），因此不断循环错误消息。

现在这段代码远非完美，它仍然可以很容易地改进，但这应该可以帮助你开始。

package tests;

import java.util.InputMismatchException;
import java.util.Scanner;

public class Tester {

    public static void main(String []args){
        int count=0;
        int days;
        int cus;
        int carType;
        double dailyFee=0, nonTaxTotal, total,fullTotal=0;
        boolean checkRunOrQuit = false, chooseTypeVehicle = false, numberOfDAysChosen = false;
        Scanner in=new Scanner(System.in);


        while ( !checkRunOrQuit ) {
            System.out.print("Press 1 to enter Rental Calculator or else press 0 to quit\n");
            System.out.println("Please only enter 1 or 0. Also, please only enter number(s) not letter(s)");
            try {
                cus=in.nextInt();
                switch ( cus ) {
                    case 0: System.out.println("End of application");
                            System.exit(0); // This will actually end your application if the user enters 0, no need to verify later on
                    break;
                    case 1: checkRunOrQuit = true;
                    break;
                    default:
                            System.out.println("Number must be either 1 or 0");
                }
            } catch (InputMismatchException ex) {
                System.out.println("Invalid entry: ");
                in.next();
            }
        }

        while( !chooseTypeVehicle ) { // --> simplified comparison
            count++;
            System.out.print("What vehical would you like to rent?\n");
            System.out.println("Enter 1 for an economy car");
            System.out.println("Enter 2 for a sedan car");
            System.out.println("Enter 3 for an SUV");

            try {
                carType = in.nextInt();
                chooseTypeVehicle = true;
                switch ( carType ) {
                    case 1: dailyFee = 31.76;
                    break;
                    case 2: dailyFee = 40.32;
                    break;
                    case 3: dailyFee = 47.56;
                    break;
                    default:
                        System.out.print("Number must be 1-3\n");
                        System.out.println("Please enter 1 for an economy car");
                        System.out.println("Enter 2 for a sedan car");
                        System.out.println("Enter 3 for an SUV");
                        chooseTypeVehicle = false;
                        break;
                }
            } catch (InputMismatchException ex) {
                System.out.println("Answer must be a number");
                in.next(); // -> you forgot this one.
            }
        }

        while ( !numberOfDAysChosen ) {
            try {
                System.out.print("Please enter the number of days rented. (Example; 3) : ");
                days = in.nextInt();
                if (days <= 0) {
                    System.out.println("Number of days must be more than zero");
                } else {
                    nonTaxTotal = (dailyFee * days);
                    total = (nonTaxTotal * 1.06);
                    fullTotal+=total;
                    numberOfDAysChosen = true;
                }
            } catch(InputMismatchException ex) {
                System.out.println("Answer must be a number");
                in.next();
            }
        }
        in.close();
        System.out.println("Count of customers : " + count);
        System.out.printf("total of the Day : $ %.2f", fullTotal);
    }
}

Answer 2

给你，我稍微修改了一下，把整个东西放在一个 while 循环中（while (cus != 0)）现在它工作得很好，试试这个代码，如果你有问题，请告诉我

p>

package inter;

import java.util.InputMismatchException;
import java.util.Scanner;

public class Inter {

    public static void main(String []args){
    int count=0;
    int days;
    int cus = 10; // added
    double DailyFee=0, NontaxTotal, CarType, Total,FullTotal=0;
    boolean F1 = false, F2 = false;
    Scanner in=new Scanner(System.in);

    while (cus != 0) {

        while (true) {  
            System.out.println("If there are any customer press 1 else press 0");
        try {           
            cus=in.nextInt();
            if (cus == 0 || cus == 1) {  
                break;
            } else {
                System.out.println("Number must be either 1 or 0");
            }
        } catch (InputMismatchException ex) {
            System.out.println("Invalid entry");
            in.next();
        }
    }

        if(cus == 1) {           
            while(F1 == false) {
                F1 = true;
                count++;
                System.out.print("What vehical would you like to rent?\n");
                System.out.println("Enter 1 for an economy car");
                System.out.println("Enter 2 for a sedan car");
                System.out.println("Enter 3 for an SUV");
                try {
                    CarType = in.nextInt();
                    if (CarType <= 0 || CarType >= 4) {
                        System.out.print("Number must be 1-3\n");
                        System.out.println("Please enter 1 for an economy car");
                        System.out.println("Enter 2 for a sedan car");
                        System.out.println("Enter 3 for an SUV");
                        F1 = false;
                    } else {
                         if (CarType == 1) {
                             F1 = true;
                              DailyFee=31.76;
                    } else if(CarType == 2) {
                            F1 = true;
                              DailyFee=40.32;
                    } else if(CarType == 3) {
                            F1 = true;
                              DailyFee=47.56;
                    }
                    while (F2 == false) {
                        F2 = true;
                        try { 
                            System.out.print("Please enter the number of days rented. (Example; 3) : ");                           
                            days = in.nextInt();
                            if (days <= 0) {
                                System.out.println("Number of days must be more than zero");
                                F2 = false;
                            } else {
                                //days = in.nextInt();
                                double x=days;
                                NontaxTotal = (DailyFee * x);
                                Total = (NontaxTotal * 1.06);
                                FullTotal+=Total;
                            }
                        } catch(InputMismatchException ex) {
                            System.out.println("Answer must be a number");
                            F2 = false;
                            in.next();
                            }
                        }
                    F2 = false;
                    }
                } catch (InputMismatchException ex) {
                    F1 = false;
                    System.out.println("Answer must be a number"); 
                    in.next();
                }
            }
            F1 = false;
        }
    }
    System.out.println("Count of customers : " + count);
    System.out.printf("Total of the Day : $ %.2f", FullTotal);
    }
}