RadixSort is a fast internal sort written in Java that mimics a card sorter. Source provided. It is faster than both HeapSort and QuickSort. It sorts using a comparision routine you provide to compare two elements to be sorted plus a method to extract individual bytes from the keys to be sorted. The time to sort each item unlike most sorts, does not increase with larger sorts. It depends rather on the key length.

You can test it with:
java.exe com.mindprod.radixsort.TestRadixSort