add Cart Item Promotion class
add category class
add get set and construct
add get set and construct in Category calss
add CartItem class
add get set and construct in CartItem calss
add get set and construct in Cart calss
delete useless annotation
delete useless annotation in Cart
delete useless annotation in CartItem
delete useless anonation in Category
delete useless annotation in Promotion
add addItem function in Cart
change num int to double
change num int to double
add Scanner class
add Scanner class
update num to double
add Load class
add filed and get and set