Question

我在这里有一个代码，我试图运行。我试图写一个循环，当我输入0时，它将停止提示我从我写的任务。出于某种原因，我只能三次输入问题的答案。由于某种原因，当程序返回项目编号时，打印输出的摘要是错误的。 Bellow（end）ill提供打印输出。我认为这与我的ShoppingBag类有关。提前谢谢！

 public class ShoppingBag
 {    
    private int items;
    private float totalRetailCost;
    private float taxRate;

    public ShoppingBag(float taxRate)
    {
        this.taxRate = taxRate;
        items = 0;
        totalRetailCost = 0.0f;
    }
    public void place(int numItems, float theCost)
    {
        items += numItems;
        totalRetailCost += (numItems * theCost);
    }
    public int getItems()
    {
        return items;
    }
    public float getTotalRetailCost()
    {
        return totalRetailCost;
    }
    public float getTotalCost()
    {
        return totalRetailCost*(1+taxRate);
    }
    public String toString()
    {       
        String result = "the bag contains " + items + " items";
        result += "The retail cost of the items is = " + 
        totalRetailCost; return result += "The total cost = " + 
        getTotalCost();
    }
}

import java.util.*;

public class MainClass 
{

    public static void main(String[] args)
    {
        Scanner conIn = new Scanner (System.in);
        ShoppingBag sb = new ShoppingBag(0.06f);

        int count = 0;
        float cost = 0.0f;

        System.out.print("Enter count (use 0 to stop): ");

        count = conIn.nextInt();

        while (count != 0)
        {
            System.out.print("Enter Cost");
            cost = conIn.nextFloat();
            sb.place(count, cost);

            System.out.print("Enter count (use 0 to stop): ");
            count = conIn.nextInt();
            System.out.print(sb);

        }
        conIn.close();
    }   
}

打印

输入计数（使用0停止）：5 输入Cost10.5 输入计数（使用0停止）：2（此处应保持运行，因为没有输入0）袋子包含5件物品零售成本= 52.5总成本= 55.649998成本

（应该说7项而不是5项）

Answer 1

问题出在这里，你在每次迭代时打印行李（检查最后一次打印）。这也是错误项目计数的问题。该项目不可用，因为您尚未将其放入包中。您可能希望在循环后打印bag对象，或者如果您想知道您的包在输入中间包含的内容

// After the loop
while (count != 0)
{
   System.out.print("Enter Cost");
   cost = conIn.nextFloat();
   sb.place(count, cost);

   System.out.print("Enter count (use 0 to stop): ");
   count = conIn.nextInt();
}
System.out.print(sb);

// After you placed the object in the bag,
// If you want the user to know what he has after each insertation
while (count != 0)
{
   System.out.print("Enter Cost");
   cost = conIn.nextFloat();
   sb.place(count, cost);

   System.out.print(sb);
   System.out.print("Enter count (use 0 to stop): ");
   count = conIn.nextInt();
}

编辑：作为旁注，你的循环确实运行了，你只是认为它已经结束了，因为你看到了打印袋。循环本身没有停止，你只需要输入继续那里。

我的while循环不会运行

打印

1 个答案: