Java developers

hello, i'm a bit new here... was wondering if anyone could help

I am trying to use a Comparable Interface to sort objects of an arrayList
and everything functions and compiles except the sorting statement which returns the error:
"insertionSort(java.lang.Comparable) in Sorts cannot be applied to (java.util.ArrayList)"

( here's a coding example..Collapse )

what should I use? array, vector, list?

I have pairs of data

a user ID, and and IP associated with that User ID.

the initially I will have no data to insert and the collection will change in size once a user logs in.

I'm thinking about using XPath for an app I'm writing. Anyone have any recommendations for Java tools to do it? I've been looking at Xalan but it'd be nice to hear from someone who's actually tried some of this stuff.