I know about SortedSet, but in my case I need something that implements List, and not Set. So is there an implementation out there, in the API or e
Off the top of my head, lists allow duplicates. You could quickly implement a UniqueArrayList and override all the add / insert functions to check for contains() before you call the inherited methods. For personal use, you could only implement the add method you use, and override the others to throw an exception in case future programmers try to use the list in a different manner.