So I have an ArrayList list that is storing some Integers in it and I need to sort them so that I can do some math on them. I've got the ArrayName.toArray passing to array to store the numbers. Then I'm running the Arrays.sort on it and it throws a NullPointerException any idea why it would do this?

I'm working on an assignment where I need to make an interactive course catalog. I'm suposed to read from two text files, one that list the classes and the outgoing proficiencies the other lists the classes and the need proficiencies to take that class. The files are formated such that the first thing in each line is the class name then a comma followed by the first proficiency the class gives you then a comma and so on.