insertsort

public void insertSort(Object o) {		if (IsEmpty())			insert(o);				if (contains(o)) {			//SOLLEVA ECCEZIONE			return;		}				if (((Comparable) o).compareTo(startnode.info) < 0) {			startnode = new Node (o, startnode);			return;		}				Node precnode = startnode;		Node currnode = startnode.next;		while (currnode != null) {			if	((((Comparable) o).compareTo(precnode.info) > 0) || 				 (((Comparable) o).compareTo(currnode.info) < 0)) {				precnode.next = new Node(o,currnode);				return;			}			precnode = precnode.next;			currnode = currnode.next;		}		precnode.next = new Node(o);	}