购物车计划
我一直在研究我的购物车程序，但是我一直有输入itemTax的问题以及在购物车中添加新商品时我不知道我做错了什么。
class级项目：
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"); } }
类商店：
import java.util.ArrayList; import java.util.Scanner; public class Shop { public static void main(String[] args) { Scanner sc = new Scanner(System.in); ArrayList cart = new ArrayList(); 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; } } } }
这段代码看起来……可疑……
private static Item[] cart = new Item[capacity]; public Cart(){ itemCount = 10; totalPrice = 0.0; capacity = 0; }
你没有提供实例化Cart其他方法，因此每次你新Cart时，你都有一个大小为0的购物车。没有任何东西可以添加到那里。
我愿意打赌，在语义上，你的意思是做这样的事情：
private Item[] cart; public Cart(){ itemCount = 0; totalPrice = 0.0; capacity = 10; cart = new Item[capacity]; }
您现在有10个项目的容量，并且应该使用itemCount代替add方法中的capacity ，以将元素移动到适当的位置。
尝试：
BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); String s = br.readLine();
得到购物狂的输入