需求：1、寫一個商品類，有商品編號、商品名稱、商品分類、商品單價屬性。2、寫一個商品條目資訊類，有商品和數量兩個屬性，有商品總價格方法。

3、寫一個購物車類，有新增商品方法、檢視訂單資訊，刪除商品，修改商品，清空購物車，求購物車中所有商品總金額方法。4、寫一個測試類，測試上述方法。

商品類：

public class Product {
	private int productId;// 商品編號
	private String productName;// 商品名稱
	private String category;// 商品分類
	private double price;// 單價

	public Product() {// 無參構造
		super();
	}

	public Product(int productId, String productName, String category,
			double price) {
		super();
		this.productId = productId;
		this.productName = productName;
		this.category = category;
		this.price = price;
	}

	public String toString() {
		return "Product [productId=" + productId + ", productName="
				+ productName + ", category=" + category + ", price=" + price
				+ "]";
	}

	public int getProductId() {
		return productId;
	}

	public void setProductId(int productId) {
		this.productId = productId;
	}

	public String getProductName() {
		return productName;
	}

	public void setProductName(String productName) {
		this.productName = productName;
	}

	public String getCategory() {
		return category;
	}

	public void setCategory(String category) {
		this.category = category;
	}

	public double getPrice() {
		return price;
	}

	public void setPrice(double price) {
		this.price = price;
	}

}
 

public class ProductItem {
	private Product product;//購買的商品
	private int count;//商品數量
	public double totalMoney(){//小計
		double price=product.getPrice();//獲取商品單價
		return price*count;
	}
	
	public ProductItem() {
		super();
	}

	public ProductItem(Product product, int count) {
		super();
		this.product = product;
		this.count = count;
	}

	public Product getProduct() {
		return product;
	}
	public void setProduct(Product product) {
		this.product = product;
	}
	public int getCount() {
		return count;
	}
	public void setCount(int count) {
		this.count = count;
	}
	
}
 

import java.util.Collection;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.Map;
public class ShoppingCart {//購物車
	//key：商品編號 value:商品條目
	private Map<Integer,ProductItem> map=new LinkedHashMap<Integer,ProductItem>();
	
	public void addProduct(Product p){//新增商品
		int productId=p.getProductId();
		if(map.containsKey(productId)){
			ProductItem productItem=map.get(productId);
			productItem.setCount(productItem.getCount()+1);
		}else{
			map.put(productId, new ProductItem(p,1));
		}
	}
	public void showAll(){//檢視訂單資訊
		Collection<ProductItem> productItems = map.values();
		Iterator<ProductItem> iterator = productItems.iterator();
		while(iterator.hasNext()){
			ProductItem productItem = iterator.next();
			Product product = productItem.getProduct();
			System.out.println("商品編號："+product.getProductId()+",商品名稱："
			+product.getProductName()+",單價："+product.getPrice()+",數量："+productItem.getCount()
			+",小計："+productItem.totalMoney());
		}
	}
	public boolean deleteProduct(int productId){//刪除商品
		if(map.containsKey(productId)){
			map.remove(productId);
			return true;
		}
		return false;
	}
	public boolean modifyProduct(int productId,int count){//修改
		if(map.containsKey(productId)){
			if(count>=1){
				ProductItem productItem = map.get(productId);
				productItem.setCount(count);
				return true;
			}else if(count==0){//刪除該商品
				deleteProduct(productId);
				return true;
			}	
		}
		return false;
	}
	
	public void clearCart(){//清空購物車
		map.clear();
	}
	
	public double totalAllMoney(){//商品總錢數
		double total=0;
		Collection<ProductItem> productItems = map.values();
		Iterator<ProductItem> iterator = productItems.iterator();
		while(iterator.hasNext()){
			ProductItem productItem = iterator.next();
			double money=productItem.totalMoney();
			total+=money;
		}
		return total;
	}
}
 

public class ShoppingCartTest {

	public static void main(String[] args) {
		ShoppingCart cart=new ShoppingCart();
		Product p1=new Product(101,"華碩筆記本","筆記本",4599);
		Product p2=new Product(102,"蘋果","水果",5.9);
		Product p3=new Product(103,"彩電","家電",2799);
		Product p4=new Product(104,"秋褲","服裝",128);
		Product p5=new Product(105,"華為手機","手機",2998);
		Product p6=new Product(101,"華碩筆記本","筆記本",4599);//測試買兩件商品的情況
		cart.addProduct(p1);
		cart.addProduct(p2);
		cart.addProduct(p3);
		cart.addProduct(p4);
		cart.addProduct(p5);
		cart.addProduct(p6);
		cart.showAll();
		System.out.println("############");
		boolean flag=cart.deleteProduct(p2.getProductId());
		if(flag){
			System.out.println("商品編號為："+p2.getProductId()+"的商品刪除成功！");
		}else{
			System.out.println("刪除失敗");
		}
		cart.showAll();
		System.out.println("############");
		boolean flag2=cart.modifyProduct(p3.getProductId(), 2);
		if(flag2){
			System.out.println("商品編號為："+p3.getProductId()+"的商品修改成功！");
		}else{
			System.out.println("修改失敗");
		}
		cart.showAll();
		
		//cart.clearCart();
		//cart.showAll();
		System.out.println("商品總價錢為："+cart.totalAllMoney());

	}

}