使用Java语言编写一个模拟网上超市购物结算功能的程序，要求程序运行后有一个图形用户界面，可供用户查询购买的各种商品相关信息，最后给出用户的购物清单及价格，并且用户可以根据需要查询自己购买的第几项商品的详细信息。

需求分析：

1．用户每购买一种商品就在购物车中添加一条信息，添加的信息包括商品名称、数量和单价

2．用户可以删除已购买的某一种商品

3．用户可以查询已购买的一种商品的详细信息，查询时要指明查询的商品的记录号是多少（商品记录号是按照商品购买次序编的），还可以指定查询第一个或最后一个购买的商品信息。

4．用户可以删除所有已添加到购物车的商品

5．用户可以打印要购买的商品的清单

6．用户可以清空显示信息的窗口

7．用户可以要求结帐，系统会打印出用户购物清单，并给出总价。

-Use Java language to write a simulated online supermarket shopping settlement function of the procedure, requirement after the program is running, a graphical user interface for the user query to buy all kinds of merchandise information, finally gives the user s shopping list and price, and the user can according to the track of what items need to check your purchase details.

Demand analysis:

1. Users each buy a commodity in the shopping cart to add a message, add the information including name of commodity, quantity, and unit price

2. The user can delete has to buy a certain commodity

3. The user can query has to buy a commodity detailed information of the query to specify the query goods record number is how many (goods record number is according to purchase order of commodity), you can also specify query first or the last one to buy the commodity information.

4. The user can delete all the articles have been added to the shopping cart

5. The user can print to purchase the comm