java - 我的 while 循环无法运行

Question

我这里有一个代码正在尝试运行。我正在尝试编写一个循环，当我输入 0 时，它将停止提示我执行我编写的任务。由于某种原因，我只能输入问题答案三次。另外，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。波纹管(结束)将提供打印输出。我认为这与我的 ShoppingBag 类(class)有关。提前致谢!

 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();
    }
}

<小时/>

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();
    }   
}

打印出来

输入计数(使用 0 停止):5输入成本10.5输入 count (使用 0 停止): 2 (这里应该继续运行，因为没有输入 0)该包包含 5 件元素元素的零售成本为 = 52.5 总成本 = 55.649998输入成本

(应该说 7 项而不是 5 项)

Answer 1

问题就在这里，你在每次迭代时打印袋子(检查最后一次打印)。这也是项目计数错误的问题之一。该元素不可用，因为您尚未将其放入包中。您可能想在循环后打印 bag 对象，或者如果您想知道您的 bag 在输入中间包含什么

// 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，您的循环确实运行了，您只是认为它已经结束，因为您看到了袋子打印。循环本身并没有停止，您只需进行输入即可继续。