While-Loop完成問題和最終值計算

Question

我在使用循環語句時遇到問題，如果沒有恢復原來的循環條件，就無法正常執行。 此外，如果我希望我的最終輸出包含所購買產品總數的定價值，我將如何實現這一目標？

最終產品需求：客戶購買所有9件商品

請輸入你的名字：John Smith

GRAPEFRUIT產品

1. gPod shuffle $ 49
2. gPod Touch $ 299
3. gPad Mini $ 329
4. gPad 2 399美元
5. gPhone 199美元
6. gMac 1299美元
7. MacNovel Pro 1199美元
8. MacNovel Air $ 999
9. MiniMac 599美元
10. 完成我的訂單

請從上面的菜單中選擇一個項目：5

請從上面的菜單中選擇另一個項目：2

請從上面的菜單中選擇另一個項目：7

請從上面的菜單中選擇另一個項目：9

請從上面的菜單中選擇其他項目：3

請從上面的菜單中選擇其他項目：4

請從上面的菜單中選擇其他項目：6

請從上面的菜單中選擇其他項目：1

請從上面的菜單中選擇另一個項目：8

請從上面的菜單中選擇另一個項目：10感謝您訂購Grapefruit Company，John Smith

訂購的商品總數：9

訂購的商品價格：5371美元

銷售稅：349.115美元

應付總額：5720.115美元

這是我的代碼：

public static void main(String[] args) {

        // Declare Variables
        Scanner input = new Scanner (System.in);
        String CustomerName;
        int gpodShuffle = 1;
        int gpodTouch = 2;
        int gpadMini = 3; 
        int gpadTwo = 4;
        int gphone = 5;
        int gmac = 6;
        int macnovelPro = 7;
        int macnovelAir = 8;
        int miniMac = 9;
        int nNumber = 0;
        int nProducts = 0;
        int nTotal = 0;

        //Declare Constants 
        final int SENTINEL = 10;
        final double SALES_TAX = 6.5;
        final int GPOD_SHUFFLE = 49;
        final int GPOD_TOUCH = 299;
        final int GPAD_MINI = 329;
        final int GPAD_TWO = 399;
        final int GPHONE = 199;
        final int GMAC = 1299;
        final int MAC_NOVELPRO = 1199;
        final int MAC_NOVELAIR = 999;
        final int MINI_MAC = 599;

        //Prompt user to enter name
        System.out.println("Please enter your name: ");

        //Enter user name
        CustomerName = input.nextLine();

        //Print Blank Line 
        System.out.println("");

        //Begin Product Listing
        System.out.println("GRAPEFRUIT PRODUCT:");

        System.out.println("1. gPod shuffle $49");

        System.out.println("2. gPod Touch   $299");

        System.out.println("3. gPad Mini    $329");

        System.out.println("4. gPad 2       $399");

        System.out.println("5. gPhone       $199");

        System.out.println("6. gMac         $1299");

        System.out.println("7. MacNovel Pro $1199");

        System.out.println("8. MacNovel Air $999");

        System.out.println("9. MiniMac      $599");

        System.out.println("10. Complete my order");

        //Keep reading until the input is 10
        while (nNumber != SENTINEL) {
            //Calculate entered items
            nTotal = nTotal + nNumber;

            nProducts++;

        System.out.println("\nPlease select an item from the menu above: ");

        //Read number entered by the user
        nNumber = input.nextInt();

        if (nNumber == SENTINEL) 
        System.out.println("Thank you for ordering with Grapefruit Company, " + CustomerName);
        else if  (nNumber != SENTINEL) 
        System.out.println("Please select another item from the menu above: ");
        } //End Loop



        //Process selections entered by the user

            //Increment count 


            //Print blank line to screen
            System.out.println("");

            //Total amount of product ordered
            System.out.println("Total items ordered: ");

            //Total price of items ordered
            System.out.println("Price of items ordered: ");

            //Sales tax associated with the purchase
            System.out.println("Sales tax: " + SALES_TAX);

            //Total amount due by the customer to Grapefruit Co. 
            System.out.println("Total amount due: ");


      }

    }

Answer 1

對於某些要添加的類來說，這非常令人煩惱，因此您可以輕松地遍歷這些項目。

不過你可以在這個場景中做些什么：

• 保持數組中項目的價格。

   int [] itemPrices = {49,299,329,399,199,1299,1199,999,599}; 

• 更新您的打印報表

   System.out.println("1. gPod shuffle $" + prices[0]); System.out.println("2. gPod Touch $" + prices[1]); System.out.println("3. gPad Mini $" + prices[2]); System.out.println("4. gPad 2 $" + prices[3]); System.out.println("5. gPhone $" + prices[4]); System.out.println("6. gMac $" + prices[5]); System.out.println("7. MacNovel Pro $" + prices[6]); System.out.println("8. MacNovel Air $" + prices[7]); System.out.println("9. MiniMac $" + prices[8]); 

• 更新while循環以引用這些項目價格

   // Keep reading until the input is 10 while (nNumber != SENTINEL) { System.out.println("\\nPlease select an item from the menu above: "); // Read number entered by the user nNumber = input.nextInt(); if (nNumber == SENTINEL) { System.out.println("Thank you for ordering with Grapefruit Company, " + CustomerName); // The user's just entered the value held for SENTINEL - leave the while loop. break; } // Calculate the total price. nTotal = nTotal + prices[nNumber-1]; // Increment the total number of products entered. nProducts++; } 

• 更新您的最終打印聲明：

    //Total amount of product ordered System.out.println("Total items ordered: " + nProducts); //Total price of items ordered System.out.println("Price of items ordered: "+nTotal); //Sales tax associated with the purchase System.out.println("Sales tax: " + SALES_TAX); 

我會告訴你如何獲得總金額:)

Answer 2

要解決此連接問題，您遇到的問題是：

System.out.println("Total amount due: " + ((SALES_TAX * nTotal) + nTotal));

這意味着在將其轉換為字符串之前執行完整計算。

但背后的數學是錯誤的，而不是做類似如下：

// Calculate the amount of tax.
double salesTax = (SALES_TAX/100) * nTotal;
System.out.println("Sales tax: " + salesTax);

你應該這樣做：

//Total amount due by the customer to Grapefruit Co. 
System.out.println("Total amount due: " + (salesTax + nTotal));