Question

我有这个主要课程

public class Hotel
{
  Scanner scan = new Scanner(System.in);
  Register[] items = new Register[15];
  int count = 0;

  public static void main(String[] args)
  {
    DecimalFormat fmt = new DecimalFormat("0.##");
    Hotel run = new Hotel();
    int quantity, sale,night;
    Register deluxe = new Deluxe();
    Register family = new Family();
    Register suite = new Suite();

    Scanner input = new Scanner(System.in);
    System.out.println("Enter customer's name:");
    String name = input.next();

    run.enterItems();
    if(run.count != 0)
    {
    System.out.println("\nHotel Reservation Payment");
    System.out.println("============================");
    System.out.println("Customer name: " + name);
    deluxe.displayInfo(); //supposed to print the details
    family.displayInfo(); //supposed to print the details
    suite.displayInfo();  //supposed to print the details
    System.out.println("The final total is RM" + fmt.format(run.calcTotal()));
    }
    else
    {
      System.out.println("No items entered.");
      run.enterItems();
    }
 }

 public double calcTotal()
  {
    double total = 0;
    for(int i = 0;i<count;i++)
    {
      total += items[i].total();
    }
    return total;
  }

应该将我在扫描仪中输入的值返回到类中作为主类的enterItems()

public void enterItems()
{
    int type, quantity, sale,night;
    double price;
  ............................

    System.out.println("\nNow please enter how many of Deluxe Room you want to book.");
    quantity = scan.nextInt();
    System.out.println("\nHow many night?");
    night = scan.nextInt();
    items[count] = new Deluxe(quantity,sale,night);
    count++;
}

所以这将传递给名为Deluxe的类，其中我有一个名为displayInfo()的方法

public class Deluxe implements Register
{
int quantity,night;
double sale;
public Deluxe(){}

....................................

public double total()
{
    double total, price = 200.0;
    price = price*quantity*night;
    total = price - (price * (sale/100));
    total += total *.06;
    return total;
}

public void displayInfo(){
    if (quantity > 0){
    System.out.println("Room Type : Deluxe Room"); 
    System.out.println("Quantity: " +quantity);
    System.out.println("Discount: " +sale);
    }
 }
}

问题是，在检查quantity > 0时，它实际上没有得到我在扫描仪中输入的任何值。无论我投入多少金额，它总是会返回0。但计算工作正常。计算是计算房间预订多少（数量）房间x房间的价格。该计算也与类displayInfo()中的Deluxe属于同一类。

所以我想知道我在这里做错了什么。

Answer 1

您在此处输入的数量：

System.out.println("\nNow please enter how many of Deluxe Room you want to book.");
quantity = scan.nextInt();

进入此处定义的main(String[] args).quantity：

public class Hotel
{
....
public static void main(String[] args)
{
...
int quantity, sale,night;
 ...
 }

您在此处查看的数量：

if (quantity > 0){...}

是一个不同的参数 - 它是Deluxe.quantity并在此处定义：

public class Deluxe implements Register
{
int quantity,night;
...
}

这两个参数没有关系。如果您希望它们都相同，则需要将Deluxe参数传递给类main(String[] args).quantity。您可以通过Hotel.main(String[] args)下的自己的构造函数执行此操作，如下所示：

DecimalFormat fmt = new DecimalFormat("0.##");
Hotel run = new Hotel();
int quantity, sale,night;
Register family = new Family();
Register suite = new Suite();

Scanner input = new Scanner(System.in);
System.out.println("Enter customer's name:");
String name = input.next();

quantity = run.enterItems();
Register deluxe = new Deluxe(quantity,0,0); // entering the default value for the other two parameters like the empty constructor would leave them.
if(run.count != 0)
{
System.out.println("\nHotel Reservation Payment");
System.out.println("============================");
System.out.println("Customer name: " + name);
deluxe.displayInfo(); //supposed to print the details
family.displayInfo(); //supposed to print the details
suite.displayInfo();  //supposed to print the details
System.out.println("The final total is RM" + fmt.format(run.calcTotal()));
}
else
{
  System.out.println("No items entered.");
  run.enterItems();
}

如果您更改enterItems()函数以返回所需的数量参数，例如：

public int enterItems()
{
int type, quantity, sale,night;
double price;
.........
System.out.println("\nNow please enter how many of Deluxe Room you want to book.");
quantity = scan.nextInt();
System.out.println("\nHow many night?");
night = scan.nextInt();
items[count] = new Deluxe(quantity,sale,night);
count++;
return quantity;
}

注意，这仅针对数量参数解决了这个问题。如果您需要更多内容，则可能需要从Deluxe返回enterItems()结构。祝你好运！

主类java不返回使用scanner传递的值

1 个答案: