带有OOP的Java应用程序杂货订购逻辑

问题描述

我正在做杂货订购系统，但订购逻辑有问题。

当前，该程序会询问客户他们要订购多少杂货，但我发现这是一种订购方法，而无需在开始时指定要订购的订购数量。

有人知道吗？谢谢。

下面是驱动程序类Shop.java

package groceries.ordering.system;


import java.util.*;


public class Shop {
    
    public static void main(String[] args){
        
        Scanner myScanner = new Scanner(System.in);
      
        Category[] groceries = {new Category("Apple 1pcs",1.5,"Fruit"),new Category("Orange 1pcs",1.4,new Category("Egg 10pcs",8,"Dairy"),new Category("Full Cream Milk",6.5,new Category("Olive Oil 1L",30,"Cooking Oil"),new Category("Palm Oil 1L",20,"Cooking Oil")};
                            
                   
        displayMenu(groceries);

        System.out.print("How many groceries you would like to order: ");
        int totalGroceries = myScanner.nextInt();
        
        OrderItem[] items = new OrderItem[totalGroceries];
        
        for(int i=0;i<items.length;i++){
        System.out.println("Enter your choice of groceries (1 - 6) : ");
        int choice = myScanner.nextInt()-1;
        System.out.println("Enter quantity ordered: ");
        int quantity = myScanner.nextInt();
        
        items[i] = new OrderItem(groceries[choice],quantity);
      }
        
        Order order = new Order(items,totalGroceries);
          displayOrderItem(items);
          System.out.printf("%65s %9.2f\n","Grand Total: ",order.getGrandTotalPrice());

    } 

     public static void displayMenu(Groceries[] groceries){
        
        System.out.printf("\t========================================\n");
        System.out.printf("\tWelcome to the Groceries Ordering System\n");
        System.out.printf("\t========================================\n");
        System.out.printf("%-10s %-25s %-11s %s \n\n","No","Groceries","Price(RM)","Category");
        for(Groceries grocery : groceries){
            System.out.println(grocery.displayMenu());
            
        }
        System.out.println("\n");
    }
     
     public static void displayOrderItem(OrderItem[] items){
        System.out.printf("\n\t\t\t\t Ordered Item\n");
        System.out.printf("\t\t\t\t===============\n");
        System.out.printf("%-10s %-20s %-14s %-13s %-13s\n","Quantity","Total Price(RM)");
        System.out.printf("--------------------------------------------------------------------------------------\n");
        for(OrderItem item : items){
            System.out.println(item.displayOrder());
        }
        System.out.printf("--------------------------------------------------------------------------------------\n");
    }     
       
}

这是Groceries类（我认为不会发布任何相关类，因此不会发布该类的子类（类别）

package groceries.ordering.system;


public abstract class Groceries {
    
    private String name;
    private double price;

    public Groceries() {
        this("",0);
    }
    
    public Groceries(String prodName,double prodPrice){
        super();
        name = prodName;
        price = prodPrice;
    }

    public String getName() {
        return name;
    }

    public double getPrice() {
        return price;
    }

    public String displayMenu(){
        return String.format("%-25s %-11.2f ",name,price);
    }


}

这是OrderItem类

public class OrderItem {
    
    private Groceries groceries;
    private int quantity;
    private static int prodCount = 1;
    
    public OrderItem(Groceries groceries,int quantity) {
        this.groceries = groceries;
        this.quantity = quantity;
    }
    
    public double getUnitPrice(){
     return groceries.getPrice();
        
    }
    
    public double getSubTotalPrice(){
        return getUnitPrice() * quantity;
    }
    

    public String displayOrder() {
        return String.format("%-10d %-20s %9.2f %13d %19.2f",prodCount++,groceries.getName(),getUnitPrice(),quantity,getSubTotalPrice());
    }
}

最后是Order类

public class Order {
    
    private OrderItem[] items;
    private int totalItem;

    
    public Order(OrderItem[] items,int totalItem) {
        this.items = items;
        this.totalItem = totalItem;
    }

    
    public double getGrandTotalPrice() {
        double price = 0.0;
        for (OrderItem item : items) {
            price += item.getSubTotalPrice();
        }
        return price;
    }
       
}

解决方法

好的。您可以通过两种方式做到这一点。

1. 事先创建一个非常大的数组（不推荐）。
2. 使用一些List（ArrayList或LinkedList等），并继续添加项目，直到完成用户操作。

List<OrderItem> items = new ArrayList<>();
    
do {
    System.out.println("Enter your choice of groceries (1 - 6) : ");
    int choice = myScanner.nextInt()-1;
    System.out.println("Enter quantity ordered: ");
    int quantity = myScanner.nextInt();
    
    items.add(new OrderItem(groceries[choice],quantity));

    // compute shouldContinue - something like asking the user to enter -1 to quit.
} while(shouldContinue);
   
  

,

是，在数组下方的位置使用ArrayList或LinkedList的List实现并使用其功能：

替换此项-OrderItem[] items = new OrderItem[totalGroceries];

with ArrayList- List<OrderItem> items = new ArrayList<>();

如果要在多线程环境中运行此应用程序，也可以使用CopyOnWriteArrayList。