Quote:
"include an arraylist"
To do what?
Just throwing a random collection in there doesn't do anything - you need to decide on what you are trying to achieve, and then use the appropriate datatypes to achieve that goal.
Collections hold items: unless you have a use for a bunch of items held together (Whigh your current application doesn't) there is no point in throwing one into code at random!
Deciding on a datatype and trying to work out what to use it for in an existing application is not a good idea. Start with the application and what you need it to do, then work back from there.