Question

我正在寻找一个原因，无论我为discountPercentage输入消息框输入什么，此代码将仅使用下面列出的10％折扣方案。我需要做到这一点，以便计算的唯一百分比是10％，15％或25％。如果用户在discountPercentage输入消息框中输入任何其他内容，折扣将默认为价格1的10％折扣。

import javax.swing.JOptionPane;
import java.text.DecimalFormat;

public class  Assignment3 {

    public static void main(String[] args) {
        // Calculate the discount price of an item

        // Convert price to display as decimal format
            DecimalFormat df = new
            DecimalFormat("#,###,##0.00");

        // Declare discountPercentage variable    


        // Display message boxes for price and percentage entries
        double price1 = Double.parseDouble(JOptionPane.showInputDialog( null, " Enter item price (ex:2.35): "));
        double discountPercentage = Double.parseDouble(JOptionPane.showInputDialog( null, " Enter discount percentage "));
        int dicountPercentage = 0;

        // Declare if else statements for output calculations
           if (discountPercentage > 25){

           JOptionPane.showMessageDialog(null, " The discounted price is: " + "$" + df.format(price1 - .10 * price1));

           }else if (dicountPercentage == 25){

           JOptionPane.showMessageDialog(null, " The discounted price is: " + "$" + df.format(price1 - .25 * price1));

           } else if (discountPercentage > 15){

           JOptionPane.showMessageDialog(null, " The discounted price is: " + "$" + df.format(price1 - .10 * price1));

           } else if (dicountPercentage == 15){

           JOptionPane.showMessageDialog(null, " The discounted price is: " + "$" + df.format(price1 - .15 * price1));

           } else if (discountPercentage >= 10){

           JOptionPane.showMessageDialog(null, " The discounted price is: " + "$" + df.format(price1 - .10 * price1));

                                            }
                                }

由于

Answer 1

您的代码每次都会使用10％的情况，因为在discountPercentage的所有条件中，您使用值.10，每次都是完全相同的行：

       JOptionPane.showMessageDialog(null, " The discounted price is: " + "$" + df.format(price1 - .10 * price1));

也就是说，在所有这些条件下，你都有同样的路线：

       if (discountPercentage > 25){
       } else if (discountPercentage > 15){
       } else if (discountPercentage >= 10){

另请注意，此代码中有两个变量名称几乎相同：

dicountPercentage
discountPercentage

并且第一个变量设置为0且永远不会改变，所以使用dicountPercentage的所有条件都毫无意义。这种命名非常糟糕：避免使用名称非常相似的变量。（起初我甚至没有注意到有两个变量，我以为两者都是一样的......）

Answer 2

import javax.swing.JOptionPane;
import java.text.DecimalFormat;

public class  Assignment3 {

    public static void main(String[] args) {
        // Calculate the discount price of an item

        // Convert price to display as decimal format
        DecimalFormat df = new
        DecimalFormat("#,###,##0.00");

        // Declare discountPercentage variable    


        // Display message boxes for price and percentage entries
        double price1 = Double.parseDouble(JOptionPane.showInputDialog( null, " Enter item price (ex:2.35): "));
        double discountPercentage = Double.parseDouble(JOptionPane.showInputDialog( null, " Enter discount percentage "));
        //int dicountPercentage = 0;

        // Declare if else statements for output calculations
        switch(discountPercentage)
        {
        case 25:
            JOptionPane.showMessageDialog(null, " The discounted price is: " + "$" + df.format(price1 - .25 *price1));
            break;

        case 15:
            JOptionPane.showMessageDialog(null, " The discounted price is: " + "$" + df.format(price1 - .15 *price1));
            break;

        default:
            JOptionPane.showMessageDialog(null, " The discounted price is: " + "$" + df.format(price1 - .10 *price1));
            break;
        }
    }

计算折扣

2 个答案: