Question

所以我正在写一个基本的快餐订购程序，我遇到了我的任何一个循环或者返回我的一个变量时出错（所以我认为）。我的代码运行但是当我到达最后并且我不想再输入另一个订单时，它再次询问我然后显示整个食物菜单，然后输出后它允许我结束程序。我将在我认为问题出现的地方发布一半代码。我相信它也必须与userChoice变量有关。

  package lab08;

 import java.util.Scanner;
 import java.io.*;
 import java.text.DecimalFormat;

public class Lab08 {


 public static void main(String[] args) throws IOException {

    String mealName[];
    double mealPrice[];
    mealName = new String[3];
    mealPrice = new double[3];

    LoadArraysFromFile(mealName, mealPrice);
    PerformTask(mealName, mealPrice);

}

//Load Arrays From File
  public static void LoadArraysFromFile(String mealName[], double 
       mealPrice[]) throws IOException {

    File mealInfoFile;
    Scanner mealFileSC;

    mealInfoFile = new File("mealInfoFile.txt");
    mealFileSC = new Scanner(mealInfoFile);
    int cnt = 0;
    while (mealFileSC.hasNext() && cnt < 3) {
        mealName[cnt] = mealFileSC.nextLine();
        mealPrice[cnt] = mealFileSC.nextDouble();
        mealFileSC.nextLine();

        cnt++;
    }
    mealFileSC.close();

}

  //Process Each Customer
   public static void PerformTask(String mealName[], double mealPrice[])
        throws IOException {

    char userChoice;
    userChoice = 'Z';
    while (userChoice != 'N') {
        userChoice = GetUserChoice();
        ProcessEachCustomer(mealName, mealPrice);
    }
}




//Get User Choice    
 public static char GetUserChoice() {
    char userChoice;

    Scanner kbd = new Scanner(System.in);

    System.out.print("Would you like to Order? (Y/N) ");
    userChoice = kbd.nextLine().toUpperCase().charAt(0);

    while (userChoice != 'Y' && userChoice != 'N') {

        System.out.print("Would you like to Order? (Y/N)");

        userChoice = kbd.nextLine().toUpperCase().charAt(0);

    }

    return userChoice;
}



    //Process Each Customer    
      public static void ProcessEachCustomer(String mealName[],
        double mealPrice[])throws IOException {

    int mealNumber;
    double[] mealTotals = new double[3];
    int[] quantities = new int[3];
    double[] totals;
    char userChoice;
     userChoice = 'Z';


    while (userChoice != 'N') {

        ProcessEachMeal(quantities, mealName, mealPrice);
        totals = UpdateMealTotals(mealPrice, mealTotals, quantities);
        DisplayOrderSummary(mealPrice, mealTotals, quantities, totals, 
         mealName);
         LogTransaction( mealPrice,  mealTotals,  quantities,  totals,  
         mealName);
        userChoice = GetUserChoice();


    }
}



     //Process Each Meal
      public static void ProcessEachMeal(int[] quantities, String 
       mealName[], double mealPrice[]) {
        int mealNumber;
      //loop

      Scanner kbd = new Scanner(System.in);

    DisplayMenu(mealName, mealPrice);
    mealNumber = GetMealNumber();
    UpdateQuantities(quantities, mealNumber);


     }

Answer 1

在开始GetUserChoice()之前，然后在处理订单之后，您必须先致电while-loop。

public static void PerformTask(String mealName[], double mealPrice[]) throws IOException {
    char userChoice;
    // ask for first time
    userChoice = GetUserChoice();
    while (userChoice != 'N') {
        ProcessEachCustomer(mealName, mealPrice);
        // ask again so if user is done (userChoice='N') while-loop will terminate
        userChoice = GetUserChoice();
    }
}

更新：所有方法都不存在，因此我无法运行完整的代码，但您可以采取以下措施来避免2次打印问题。

下面将确保您在执行任务时仅询问用户选择，而不是在处理每个客户时。

// Process Each Customer
public static void PerformTask(String mealName[], double mealPrice[]) throws IOException {
    char userChoice;
    userChoice = GetUserChoice();
    while (userChoice != 'N') {
        ProcessEachCustomer(mealName, mealPrice);
        userChoice = GetUserChoice();
    }
}

// Get User Choice
public static char GetUserChoice() {
    char userChoice;
    Scanner kbd = new Scanner(System.in);
    do {
        System.out.print("Would you like to Order? (Y/N) ");
        userChoice = kbd.nextLine().toUpperCase().charAt(0);
    } while (userChoice != 'Y' && userChoice != 'N');
    return userChoice;
}

// Process Each Customer
public static void ProcessEachCustomer(String mealName[], double mealPrice[]) throws IOException {
    int mealNumber;
    double[] mealTotals = new double[3];
    int[] quantities = new int[3];
    double[] totals;
    ProcessEachMeal(quantities, mealName, mealPrice);
    totals = UpdateMealTotals(mealPrice, mealTotals, quantities);
    DisplayOrderSummary(mealPrice, mealTotals, quantities, totals, mealName);
    LogTransaction(mealPrice, mealTotals, quantities, totals, mealName);
}

在我退出程序之前，循环问题使输出重复

1 个答案: