不太明白如何匹配两个数组

Question

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package order;
import java.util.Arrays;
/**
 *
 * @author Alexander
 */
public class Order {
    private static String[] products = {"Compass", "Eraser", "Pen", "Pencil","Pencil Case", "Pencil Sharpener", "Ruler", "Scissors"};
    private static double[] prices = {4.5, 0.5, 0.3, 0.6, 10, 0.3, 1.2, 2.5};
    public static int orderNum = 0; // 
    private String productName ;
    private double price;
    private int discount;
    private final int minDiscount = 0;
    private final int maxDiscount = 50;
    private int quantity;
    private final int minQuantity = 0;
    private final int maxQuantity = 1000;
    private double total;
    private String message;
    private boolean isDiscounted = false;
    private boolean isValidOrder = true;
 
    public Order (){
        isValidOrder = false;
        message =  "**ERROR** : Order number cannot be totalled as no details have been supplied.";
        orderNum++;   
       }
    public Order (String productName, int quantity) {
          this.quantity = quantity;
          this.productName = productName;
          testQuantity(quantity);
          if (isValidOrder = true){
              calculate();
          }
          orderNum++;
      }
    public Order (String productName, int quantity, int discount) {
        this.productName = productName;
        this.quantity = quantity;
        this.discount = discount;
        testQuantity(quantity);
        testDiscount(discount);
        getPrice(productName);
        if (isValidOrder = true){
              calculate();
          }
          orderNum++;        
    }
    public String getOrderDetails(){
        if(isValidOrder == true && isDiscounted == true){
            message = "Order Number: " + orderNum + "\n" + "Product Name: " + productName + "\n" + "Product Price: $" + price + "\n" + "Order Quantity: " + quantity + "\n" + "Discount: " + discount + "%" + "\n" + "Total Price: $" + total;  
        } 
        else if(isValidOrder == true && isDiscounted == false){
            message = "Order Number: " + orderNum + "\n" + "Product Name: " + productName + "\n" + "Product Price: $" + price + "\n" + "Order Quantity: " + quantity + "\n" + "Total Price: $" + total;  
        }  
        return message; 
    }

        private void getPrice(String pce) {
            Arrays.sort(products);
            int searchProductArray = Arrays.binarySearch(products, pce);
            if (searchProductArray >= 0) {
            price = prices[searchProductArray];
            productName = products [searchProductArray];
            isValidOrder = true;
            } 
            else {
            price = 0.0;
            isValidOrder = false;
            message = "**ERROR**: Invalid product name";
            }
        }
    
        public void calculate (){
            if (isDiscounted == false){
            total = quantity * price;
            }
            else {
                total = quantity * price - quantity * price * (discount/10);
                 }
        }
    
        public void testQuantity(int quantity){
              boolean isValidOrder = true;
              if (quantity <= minQuantity) {
                  message = "**ERROR**: Invalid quantity. Quantity cannot be 0 or less";
                  isValidOrder = false;
              }
              else if (quantity > maxQuantity) {
                  message = "**ERROR**: Invalid quantity. Quantity cannot be greater than 1000";
                  isValidOrder = false;
              }
              else {
                  this.quantity = quantity;
                  this.isValidOrder = true;
              }
        }

        public void testDiscount (int discount) {
              boolean isDiscounted = false;
              if (discount <= minDiscount) {
                  message = "**ERROR**: The discount rate cannot be lower than or equal to 0";
                  isDiscounted = false;
              }
              else if (discount > maxDiscount) {
                  message = "**ERROR**: The discount rate cannot be greater than 50";
                  isValidOrder = false;
              }
              else {
                  this.discount = discount;
                  this.isDiscounted = true;
                  this.isValidOrder = true;
              }
        }
       
    
       
    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        Order O1 = new Order();
        O1.getPrice("Compass");
          
        System.out.println(O1.getOrderDetails());
    }  
}

    

getPrice 方法是接收一个参数：productName。方法是分配一个 valNeed 以使用两个数组来完成此操作。一个称为 products 的数组是保存产品名称的列表。另一个称为价格的数组是保存该产品的价格。索引位置应该匹配。您需要使用 binarySearch 方法在 products 数组中找到 productName 的索引位置。一旦你有了这个位置，你就需要使用这个索引位置从价格数组中分配价格。

这是我目前所拥有的，但我不完全确定它是否正确。

Answer 1

不，一般来说这是不正确的。原因是您对 products 数组进行了排序，但未修改 price 数组，因此产品通常与它们的价格不对应，即索引位置不匹配。

  private void getPrice(String s) {
    Arrays.sort(products);  <--- sort products, but prices' indices remain unchanged
    int searchedProductIndex = Arrays.binarySearch(products, s);
    if (searchedProductIndex >= 0) {
      this.price = prices[searchedProductIndex];
      this.isValidOrder = true;
    } else {
      price = 0.0;
      isValidOrder = false;
      message = "**ERROR**: Invalid product name";
    }
  }    <--- closing curly bracket

请记住以下几点。

• 二分查找只能用于有序集合
• 当您对产品数组进行排序时，您必须相应地修改价格数组，以便索引位置匹配。你不会在你的应用中这样做。
• 另外，作为旁注，请检查您的语法。您复制的代码无法编译。例如。您错过了 getPrice 函数的右括号。