Java代码，打印客户姓名、折扣级别、原始购买价格、促销价格和节省的金额

Question

总而言之，此代码应该询问客户姓名、成员(member)级别和原始购买价格。它应该将所有这些存储在各自的变量中，如果输入了除接受的成员(member)级别之外的其他内容，则程序应该退出。所有变量存储完毕后，应按照本文末尾的格式打印出客户姓名、成员(member)级别、原购买价格、促销价格和节省金额。另外，您能否告诉我我的变量命名是否正确以及整个代码的格式是否正确。预先感谢您的帮助!

import java.util.*;
public class Discount{
    public static void main(String[] args){
        Scanner keyboard = new Scanner(System.in);
        double purchase = 0.0;
        double platinum = (purchase * .2);
        double gold = (purchase * .15);
        double silver = (purchase * .1);
        String Platinum = null;
    String Gold = null;
    String Silver = null;
    String customerName = null;
    String level = null;
    double discount = 0.0;

    System.out.print("Please enter a customer name: ");
    customerName = keyboard.nextLine();
    System.out.print("Please enter the customer's member level: ");
    level = keyboard.nextLine();

如果打印了 Silver、Gold 或 Platinum 以外的任何内容，则该部分应该退出程序；但是，无论输入什么内容，它都会退出。如果我省略这部分，它会继续询问原始购买价格是多少，但不会打印任何结果。

          if (level != "Platinum" || level != "Gold" || level != "Silver")
    {
        System.exit(0);
    }

    System.out.print("Please enter the origianl purchase price: ");
    purchase = keyboard.nextDouble();

    if (level.equals(Platinum) && purchase > 500)
    {
        discount = (platinum - (purchase*.05));
        System.out.println("Congratualations, " + customerName + "!");
        System.out.println("As a " + level + " level cardholder, you have received a 25% discount during Bedlam.");
        System.out.printf("%.2f\n", "Origianl purchase price: $" + purchase);
        System.out.printf("%.2f\n", "Promotional price: $" + discount);
        System.out.printf("%.2f\n", "Amount saved: $" + (purchase-discount));
    }
    else if (level.equals(Platinum))
    {
        discount = (platinum);
        System.out.println("Congratualations, " + customerName + "!");
        System.out.println("As a " + level + " level cardholder, you have received a 20% discount during Bedlam.");
        System.out.printf("%.2f\n", "Origianl purchase price: $" + purchase);
        System.out.printf("%.2f\n", "Promotional price: $" + discount);
        System.out.printf("%.2f\n", "Amount saved: $" + (purchase-discount));
    }
    else if (level.equals(Gold))
    {
        discount = (gold);
        System.out.println("Congratualations, " + customerName + "!");
        System.out.println("As a " + level + " level cardholder, you have received a 15% discount during Bedlam.");
        System.out.printf("%.2f\n", "Origianl purchase price: $" + purchase);
        System.out.printf("%.2f\n", "Promotional price: $" + discount);
        System.out.printf("%.2f\n", "Amount saved: $" + (purchase-discount));
    }
    else if (level.equals(Silver))
    {
        discount = (silver);
        System.out.println("Congratualations, " + customerName + "!");
        System.out.println("As a " + level + " level cardholder, you have received a 10% discount during Bedlam.");
        System.out.printf("%.2f\n", "Origianl purchase price: $" + purchase);
        System.out.printf("%.2f\n", "Promotional price: $" + discount);
        System.out.printf("%.2f\n", "Amount saved: $" + (purchase-discount));
    }
    /* Example:
            Congratulations, Marge Simpson!
    As a Silver level cardholder, you received a 10% discount during Bedlam.
    Original purchase price: $500.20
    Promotional price: $450.18
    Amount saved: $50.02 */
}
}

Answer 1

当通过错误的客户级别时，您的程序不会退出，因为比较检查不正确。您需要使用 equals 方法进行字符串比较:

if (level != "Platinum" || level != "Gold" || level != "Silver")

更改为

if (!level.equals("Platinum") || !level.equals("Gold") || !level.equals("Silver"))

!= 不会比较字符串内容，而是检查对象是否相等。

编辑从威利的回答中我意识到你需要使用 && 而不是 ||在你的 if 检查中。所以正确的条件应该是:

if (!level.equals("Platinum") &&  !level.equals("Gold") && !level.equals("Silver"))