Exercise 11-4

1. In the main method of ShoppingCart, declare, instantiate, 
     and initialize at least 3 elements in an ArrayList of Strings.  
2. Print the ArrayList and run it to test your code.  
3. Fix the error by adding an import statement.
3. Use the add method to add a new element somewhere in the 
     middle of the list.  Hint: use the overloaded add method that takes
     an index number as one of the arguments. 
4. Print the list again to see the affect.
5. Test for a particular value in the ArrayList and remove it 
     if it exists, remove it. 
     Hint: Use the contains method.  It returns a boolean 
     and takes a single argument as the search criteria.
6. Print the list again.