购物车计划 [英] Shopping cart program

问题描述

我一直在处理我的购物车计划，但是我一直在输入itemTax以及在购物车中添加新商品时遇到问题，我不知道我做错了什么。

I've been working on my shopping cart program, but I keep having problems with entering itemTax in and with adding new items into cart and I don't know what I've done wrong.

class Item：

class Item:

public class Item {

private int id;
private String name;
private double price;
private String description;
private int quantity;
private double tax;

public Item (int itemID, String itemName, double itemPrice, String itemDescription, int itemQuantity, double itemTax){
    id = itemID;
    name = itemName;
    price = itemPrice;
    description = itemDescription;
    quantity = itemQuantity;
    tax = itemTax;
}

public int getID(){
    return id;
}

public String getName(){
    return name;
}

public double getPrice(){
    return price;
}

public String getDescription(){
    return description;
}

public int getQuantity(){
    return quantity;
}

public double getTax(){
    return tax;
}

}

类购物车：

import java.util.Scanner;

public class Cart {

private int itemCount;
private double totalPrice;
private static int capacity;
private static Item[] cart = new Item[capacity];

public Cart(){
    itemCount = 10;
    totalPrice = 0.0;
    capacity = 0;
}

public void add(int itemID, String itemName, double itemPrice, String itemDescription, int itemQuantity, double itemTax){
    Item item = new Item(itemID, itemName, itemPrice, itemDescription, itemQuantity, itemTax);
    totalPrice += (itemPrice * itemQuantity);
    cart[itemCount] = item;
    itemCount += 1;
    if(itemCount==capacity)
    {
        increaseSize();
    }
}

public static void remove(String itemName){
    Scanner s = new Scanner(System.in);

    for (int i = 0; i < cart.length; i++) {
        Item remove = (Item) cart.get(i);
        if (itemName.equals(remove.getName())) {
            cart.remove(i);

        }
    }
    System.out.println("\n" + "Item " + itemName + " wasn't found.");
}

private void increaseSize()
{
    Item[] item = new Item[capacity+5];
    for(int i=0; i < capacity; i++)
    {
        item[i] = cart[i];
    }
    cart = item; 
    item = null;
    capacity = cart.length;
}

public static void prLine (int itemID, String itemName, int itemQuantity, double itemPrice, double total, double itemTax) {
    System.out.printf("\n%-10.10d %30s %10.2f %10d %10.2f", itemID, itemName, itemPrice, itemQuantity, itemTax, total);
}   

public static void prTitles () {
    System.out.printf("\n%-10s 30% %10s %10s %10s %10s", "ID", "Item", "Price", "Quantity", "Tax", "Total");
}



}

class Shop：

class Shop:

import java.util.ArrayList;
import java.util.Scanner;

public class Shop {
public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    ArrayList<Item> cart = new ArrayList<Item>();

    Item item;
    int itemID;
    String itemName;
    double itemPrice;
    String itemDescription;
    int itemQuantity;
    double itemTax;
    int ch;
    String choice;

    Cart shoppingCart = new Cart();

    while (true) {
        System.out.println("Menu:");
        System.out.println("0) Exit " + "\n"
                + "1) Add item in shopping cart" + "\n"
                + "2) Remove item from shpping cart");
        ch = sc.nextInt();

        switch (ch) {
        case 0:
            System.out.println("\n" + "Good bye!");
            System.exit(0);

        case 1:
            System.out.println("Enter item ID: ");
            itemID = sc.nextInt();

            System.out.println("Enter item name: ");
            itemName = sc.next();

            System.out.println("Enter item price: ");
            itemPrice = sc.nextDouble();

            System.out.println("Enter short description of item: ");
            itemDescription = sc.next();

            System.out.println("Enter quantity: ");
            itemQuantity = sc.nextInt();

            System.out.println("Enter tax rate:");
            itemTax = sc.nextDouble();


            shoppingCart.add(itemID, itemName, itemPrice, itemDescription, itemQuantity,       itemTax);

            break;

        case 2:
            System.out.println("Enter name of the item that you would like to remove: ");
            choice = sc.next();
            shoppingCart.remove(choice);

            break;
        }

    }
}

}

推荐答案

这段代码看起来......可疑......

This block of code looks...suspect...

private static Item[] cart = new Item[capacity];

public Cart(){
    itemCount = 10;
    totalPrice = 0.0;
    capacity = 0;
}

您没有提供其他方法来实例化购物车，所以每次你新推出的时候，你都有一个大小为0的购物车。没有什么可以添加到那个。

You provide no other way to instantiate the Cart, so every time you new one up, you have a cart of size 0. Nothing could be added to that.

我愿意打赌，在语义上，你的意思是做这样的事情：

I'm willing to bet that, semantically, you mean to do something like this:

private Item[] cart;

public Cart(){
    itemCount = 0;
    totalPrice = 0.0;
    capacity = 10;
    cart = new Item[capacity];
}

您现在有10件商品，应在添加方法中使用itemCount 代替 capacity 将元素移入适当的地方。

You have a capacity of ten items now, and itemCount should be used in place of capacity in your add method to move the elements into their appropriate spot.

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