I think you aren't getting the Exception where you think you are.
You have indented your code incorrectly, which leads you to believe that "if(aisle > 5)" is part of the if(item.compareTo . . .) block. It isn't. It is independent.
Check carefully what you have in the text file against "turkey."
BTW: How are you working out your elements.getItem()? A compareTo doesn't give -1 when there is a duplicate. I think you are actually using your Grocery class as a Collection and you want a contains() method in it.
Find a copy of Deitel's book and you will see that every } is followed by a trailing comment. A useful habit to get into. Most people think that a programmer's text editor is a
word processor, and you enter an "if" block like this:
Stage 1
Stage 2
Stage 3
Stage 4
But you shouldn't.
You should do it like this:
Stage 1
Stage 2
Stage 3
stage 4
Two benefits:
Less risk of compiler errors because you have unbalanced {}s.A comment which reminds you which block ends where.