I think that if Rajendra doesn't want to use Collections.sort (or isn't allowed to, perhaps this is a homework assignment) that Arrays.sort is also out of the question.
Ah right. I thought that with "sort the array" you meant using Arrays.sort.
That said, I don't see what advantage the arrays give you when sorting an ArrayList. The latter's get and set methods are just as fast as direct array access. (Granted, for a LinkedList it would probably be wiser to first extract the data.)