请帮我解决简单的Java程序

Question

任务是：

编写一个程序，为在XYZ书店购买任意两本书的会员提供20%的折扣。(提示:将常量变量用于20%的折扣。)

我已经做了编码，但是不能提示书名，然后显示折扣价，请在下面看到我的编码，根据需要修改。

import java.util.Scanner;

public class Book_Discount {
  public static void main(String args[]) {
  public static final double d = 0.8;
  Scanner input = new Scanner(System.in);

  int purchases;
  double discounted_price;
  System.out.print("Enter value of purchases: ");

  purchases = input.nextInt();
  discounted_price = purchases * d; // Here discount calculation takes place

  // Displays discounted price
  System.out.println("Value of discounted price: " + discounted_price); 
  }

}

Answer 1

为了提示书名，你可以写这样的东西：

/* Promt how many books */
System.out.print("How many books? ");
int bookCount = scanner.nextInt();
scanner.nextLine(); // finish the line...
double totalPrice = 0.0d; // create a counter for the total price

/* Ask for each book the name and price */
for (int i = 0; i < bookCount; ++i)
{
    System.out.print("Name of the book? ");
    String name = scanner.nextLine();  // get the name
    System.out.print("Price of the book? ");
    double price = scanner.nextDouble(); // get the price
    scanner.nextLine(); // finish the line
    totalPrice += price; // add the price to the counter
}

/* If you bought more than 1 book, you get discount */
if (bookCount >= 2)
{
    totalPrice *= 0.8d;
}

/* Print the resulting price */
System.out.printf("Total price to pay: %.2f%n", totalPrice);