I would say that Arrays.sort() always uses the same algorithm - it just has multiple implementations for different data types. It's a good algortihm, certainly, much faster than a bubble sort. But for a beginner it may well be easier to understand the bubble sort.
Well, sort of..
I found Insertion sort (on smallest arrays), Mergesort (on Object arrays) and quicksort elsewhere.
[ October 23, 2007: Message edited by: Jim Yingst ]
Hm, OK. I would argue that using insertion sort for small arrays isn't based on the type of the array and overloading. But I didn't realize that both quicksort and heapsort were in there; thanks.