比较两个数组或arraylists，找到相似和不同的值

I have two arrays (or arraylists if it is easier) of strings. I need to compare these, find which only exist in the first array, which exist in both, and which only exist in the second array. These arrays are different lengths, and may be in different orders. If necessary, I suppose I could sort them...I have two arrays (or arraylists if it is easie