Question

我在这里做作业，我遇到了问题

“TotalCharge = ptr.calculateCharge（NightsStay，perNight）”旁边会出现一个红色标记;“并且错误是double不能转换为Integer。

我尝试过研究解决问题，但没有任何工作。

非常感谢你。

      HiibiscusHotelSpa9674 ptr = new HiibiscusHotelSpa9674();
      Scanner keyboard = new Scanner(System.in);
      Integer compare = 0;
      String response = null;
      String number = null;
      Double Price = 0.00;
      Integer TotalCharge = 0;
      Integer ItemNo = 0;
      String surName;
      Integer perNight = 0;
      Integer roomNumber = 0;
      Double amountPaid = 0.0;
     String temp = null;
     String Name = null;
     Double cashPaid = 0.0;
     Double Change = 0.0;

    Integer NightsStay = 0;

    temp = JOptionPane.showInputDialog("Enter The amount of Items :");
    int Size = Integer.parseInt(temp);
    String[] ItemName = new String[Size];
    Integer[] ItemId = new Integer[Size];
    double[] ItemPrice = new double[Size];
    Integer index = 0;

    while (index < Size) {
        ItemName[index] = JOptionPane.showInputDialog("Enter The Item Name:");
        temp = JOptionPane.showInputDialog("Enter Item ID for " + ItemName[index] + " :");
        ItemId[index] = Integer.parseInt(temp);
        temp = JOptionPane.showInputDialog("Enter The Price for " + ItemName[index] + " :");
        ItemPrice[index] = Double.parseDouble(temp);
        index++;

    ptr.displayMenu(ItemName, ItemId, ItemPrice);
    Name = ptr.getDataSetA();
    cashPaid = ptr.getDataSetB(ItemId);
    Change = ptr.performCalc(cashPaid, ItemPrice);
    ptr.displayResults(Change, cashPaid);

    response = JOptionPane.showInputDialog("Sale Complete? Enter Y or N: ");
    switch (response) {
        case "N":
            perNight = ptr.GetGuestInfo();
            NightsStay = ptr.GetDate();

            TotalCharge = ptr.calculateCharge(NightsStay, perNight);
            ptr.displayGuestBill(NightsStay, TotalCharge);

            break;
        case "n":
            perNight = ptr.GetGuestInfo();
            NightsStay = ptr.GetDate();
            TotalCharge = ptr.calculateCharge(NightsStay, perNight);
            ptr.displayGuestBill(NightsStay, TotalCharge);
            break;
        default:
            JOptionPane.showMessageDialog(null, "Thank you very much and   haave a wonderful day!");
    }

    public void displayMenu(String Name[], Integer ItemId[], double Price[]) {
    System.out.printf("Item Name Item ID ItemPrice\n");
    for (int i = 0; i < Name.length; i++) {
        System.out.printf("%s\t %d\t %.2f\t\n", Name[i], ItemId[i], Price[i]);

    }
}

public String getDataSetA() {
    Scanner keyboard = new Scanner(System.in);
    String[] personalInformation = new String[2];
    String NameRoomNumber = null;
    System.out.printf("Please Enter Room Number\n");
    personalInformation[1] = keyboard.next();

    System.out.printf("Enter your Surname\n");

    personalInformation[0] = keyboard.next();
    String NameNumber = Arrays.toString(personalInformation);
    return NameRoomNumber;

}

private Double getDataSetB(Integer[] ItemId) {
    Scanner keyboard = new Scanner(System.in);
    String temp = null;
    for (int i = 0; i < ItemId.length; i++) {
        double cashPaid = 0.0;

        Integer[] Items = new Integer[ItemId.length];

        System.out.println("Please Enter the Item ID for the item");
        ItemId[i] = keyboard.nextInt();
    }
    System.out.printf("Please Enter Cash Paid\n");
    double cashPaid = keyboard.nextDouble();
    return cashPaid;
}

private double performCalc(double cashPaid, double[] Price) {
    Scanner keyboard = new Scanner(System.in);
    double Cost = 0.0;
    double change = 0.0;
    double moneyOwe = 0.0;
    for (int i = 0; i < Price.length; i++) {
        Cost = Cost + Price[i];
    }
    if (cashPaid < Cost) {
        moneyOwe = Cost - cashPaid;
        JOptionPane.showMessageDialog(null, "You are $" + moneyOwe + " short");
    } else {
        change = cashPaid - Cost;
    }
    return change;
}

private void displayResults(Double Change, Double cashPaid) {
    JOptionPane.showMessageDialog(null, "Cash Paid:$ " + cashPaid + "Change:$ " + Change + ".");
}

private Integer GetGuestInfo() {
    String temp = null;
    String Guestname = null;
    Integer FloorNum = 0;
    Integer NoofPer = 0;
    Guestname = JOptionPane.showInputDialog("Please Enter Guest Name");
    temp = JOptionPane.showInputDialog("Enter Floor Required");
    FloorNum = Integer.parseInt(temp);
    temp = JOptionPane.showInputDialog("Please Enter The Number of Persons Staying with you");
    NoofPer = Integer.parseInt(temp);
    return NoofPer;
}

private Integer GetDate() {
    String temp = null;
    Integer day = 0;
    Integer month = 0;
    Integer year = 0;
    Integer Nights = 0;

    temp = JOptionPane.showInputDialog("Please enter the Day: ");
    day = Integer.parseInt(temp);
    temp = JOptionPane.showInputDialog("Please enter the Month: ");
    month = Integer.parseInt(temp);
    temp = JOptionPane.showInputDialog("Please enter the Year: ");
    year = Integer.parseInt(temp);
    temp = JOptionPane.showInputDialog("Please enter the number of Nights staying:");
    Nights = Integer.parseInt(temp);
    return Nights;
}

private Double calculateCharge(Integer amtofNights, Integer perNight) {
    Integer floor = 0;
    double totalCharge = 0.0;
    if (floor > 4) {
        // int perNight = 0;
        int Numofnights = 0;

        totalCharge = 150 * perNight * amtofNights;
    } else {

        totalCharge = 100 * perNight * amtofNights;
    }
    return totalCharge;
}

private void displayGuestBill(Integer NightsStayed, Integer totalCharge) {

    System.out.printf("The total number of nights:%d\n", NightsStayed);

    System.out.printf("The total Charge:%d", totalCharge);
}

}

Answer 1

您无法将双精度转换为整数，因为您正在失去精度。想象一下，将3.7转换为整数，您将获得3，但会丢失大量信息。

如果您对此很好，您可以使用(int)some_double进行显式演员。

您的代码示例不包含任何类型，因此很难说您的转换发生在哪个位置。

编辑：由于您的代码示例现在包含类型，因此您的calculateCharge可能会返回一个double，但您将其存储为整数。

您应该通过执行

强制执行显式转换

TotalCharge = (int)ptr.calculateCharge(NightsStay, perNight);

Answer 2

Double是原始double之上的包装类。它可以强制转换为double，但不能直接转换为int。

如果您使用double代替Double，则会编译：

double d = 10.9;    
int i = (int)(d);

Java：执行项目的函数

2 个答案: