Efficiently finding the intersection of a variable number of sets of strings

Question

I have a variable number of ArrayList\'s that I need to find the intersection of. A realistic cap on the number of sets of strings is probably around 35 but could be more. I

Answer 1

The best option would be to use HashSet to store the contents of these lists instead of ArrayList. If you can do that, you can create a temporary HashSet to which you add the elements to be intersected (use the putAll(..) method). Do tempSet.retainAll(storedSet) and tempSet will contain the intersection.