Break语句不存储数据，仅返回最后一个值输入

Question

My break statement below works perfectly fine. There are no errors. However, when I enter multiple values for multiple products, it only returns data for the last product entered. For example, if I input productNum = 1 and numSold = 5, then productNum = 2, then numSold = 5; it will only calculate totalSales for productNum = 2 and only track return a value numSold = 5. It will "forget" the data for productNum = 1 and its numSold.

I want it to store data for numSold1 thru numSold5, and also continue to add values to totalSales. Can anyone please point in the right direction for this?

Here's my sales calculator:

public class SalesCalculator {

    private int productNum, numSold, numSold1, numSold2, numSold3, numSold4, numSold5;

    private double price1 = 2.98, price2 = 4.50, price3 = 9.98, price4 = 4.49, price5 = 6.87, totalSales = 0.00;

    public int setProductNum(int productNum) {

        this.productNum = productNum;
        return productNum;
    }

    public int setNumSold(int numSold) {

        this.numSold = numSold;
        return numSold;
    }

    public double calculateSales() {

            switch (productNum) {

                case 1:
                    totalSales += (price1 * numSold); // multiplies how much of this product was sold by its price and adds to overall sales
                    numSold1 += numSold; // tracks how much of this product was sold of this product
                    break;

                case 2:
                    totalSales += (price2 * numSold);
                    numSold2 += numSold;
                    break;

                case 3:
                    totalSales += (price3 * numSold);
                    numSold3 += numSold;
                    break;

                case 4:
                    totalSales += (price4 * numSold);
                    numSold4 += numSold;
                    break;

                case 5:
                    totalSales += (price5 * numSold);
                    numSold5 += numSold;
                    break;

                // default just breaks out of loop in case invalid product number entered
                default:
                    break;
            }

        return totalSales;
    }

public double getTotalSales() { return totalSales; }

public int getNumSold1() { return numSold1; }
public int getNumSold2() { return numSold2; }
public int getNumSold3() { return numSold3; }
public int getNumSold4() { return numSold4; }
public int getNumSold5() { return numSold5; }

// get prices, included because i wasn't sure if assignment required them or not
public double getPrice1() { return price1; }
public double getPrice2() { return price2; }
public double getPrice3() { return price3; }
public double getPrice4() { return price4; }
public double getPrice5() { return price5; }
}

Here's what takes the input:

public class SalesCalculatorTest {

public static void main(String[] args){

    SalesCalculator salesCalculator1 = new SalesCalculator();

    Scanner input = new Scanner(System.in);
    int calcSales;

    do {

        System.out.printf("\nPlease enter the product number, then press ENTER.\n");
        int productNum = input.nextInt();
        salesCalculator1.setProductNum(productNum);

        System.out.printf("\nPlease enter the quantity sold, then press ENTER.\n");
        int numSold = input.nextInt();
        salesCalculator1.setNumSold(numSold);

        System.out.printf("\nType -1 to calculate sales. Press ENTER to input more data.\n");
        calcSales = input.nextInt();
        } while (calcSales != -1);

    if (calcSales == -1) {

        salesCalculator1.calculateSales();
    }

    double totalSales = salesCalculator1.getTotalSales();
    System.out.printf("\nTotal sales for products sold was $%.2f", totalSales);

    int numSold1 = salesCalculator1.getNumSold1();
    double price1 = salesCalculator1.getPrice1();
    System.out.printf("\n\nProduct 1 sold %d units at $%.2f each", numSold1, price1);

    int numSold2 = salesCalculator1.getNumSold2();
    double price2 = salesCalculator1.getPrice2();
    System.out.printf("\nProduct 2 sold %d units at $%.2f each", numSold2, price2);

    int numSold3 = salesCalculator1.getNumSold3();
    double price3 = salesCalculator1.getPrice3();
    System.out.printf("\nProduct 3 sold %d units at $%.2f each", numSold3, price3);

    int numSold4 = salesCalculator1.getNumSold4();
    double price4 = salesCalculator1.getPrice4();
    System.out.printf("\nProduct 4 sold %d units at $%.2f each", numSold4, price4);

    int numSold5 = salesCalculator1.getNumSold5();
    double price5 = salesCalculator1.getPrice5();
    System.out.printf("\nProduct 5 sold %d units at $%.2f each\n", numSold5, price5);
}
}

Answer 1

According to the way you have designed your program, you need to call calculateSales() after each pair of calls to setProductNum() and setNumSold() .

Therefore the following line needs to be within your do ... while loop:

salesCalculator1.calculateSales();

The reason for this is that productNum and numSold are over-written with each pair of calls to setProductNum() and setNumSold() . Therefore you need to use these values while they are current. Otherwise, as you note, all your calculations will use the last set values, ie. the earlier values are "forgotten".