AP Computer Science --- Haas --- ShoppingList

Write a class called ShoppingList which allows users to add or remove items from a String, (shopping list).

The class ShoppingList has the following methods:

• public ShoppingList() - a zero parameter constructor which creats a new ShoppingList object which is empty
• public ShoppingList(String items) - a one parameter constructor which creates a shopping list with given items
• public void printList() - prints the current contents of the shopping list
• public void addItem(String anItem) - adds a new item to the end of the shopping list (only if it is NOT already on the list)
• public void removeItem(String anItem) - removes an item from the shopping list (if it on the list)

Below is a tester for ShoppingList. Note that there are NO extra commas after adding or removing items!
For example the shopping list: pickles, apples, has an extra comma! No Good!

/***********************************************************************
 * >>>>>> TESTER for class ShoppingList --- This code is complete <<<<<<
 *
 * --------------- Below is the output from this tester ----------------
 * Shopping list = 
 * Shopping list = apples
 * Shopping list = apples, spam
 * Shopping list = apples, spam, broccoli
 * Shopping list = apples, broccoli
 * Shopping list = apples, broccoli
 * Shopping list = apples, broccoli, milk
 * Shopping list = apples, milk
 * Shopping list = apples, milk
 * Shopping list = apples
 * Shopping list = apples, bread
 * Shopping list = bread
 * Shopping list = bread, milk
 *****************************************************************/
public class ShoppingListTester
{
   public static void main(String args[])
   {
       ShoppingList Haas = new ShoppingList("");
       Haas.printList();     
       Haas.addItem("apples");
       Haas.printList();     
       Haas.addItem("spam");
       Haas.printList();     
       Haas.addItem("broccoli");
       Haas.printList();     
       Haas.removeItem("spam");
       Haas.printList();      
       Haas.addItem("apples");
       Haas.printList();     
       Haas.addItem("milk");
       Haas.printList();     
       Haas.removeItem("broccoli");
       Haas.printList();      
       Haas.removeItem("chicken");
       Haas.printList();      
       Haas.removeItem("milk");
       Haas.printList();      
       Haas.addItem("bread");
       Haas.printList();      
       Haas.removeItem("apples");
       Haas.printList();      
       Haas.addItem("milk");
       Haas.printList();      
    }
}