[LIST]-Swap_nodes_without_swaping_data

public static void promeni_lista(SLL<Integer> lista, int x, int y) {
        SLLNode<Integer> d1 = lista.getFirst();
        SLLNode<Integer> dx = lista.getFirst();
        SLLNode<Integer> dy = lista.getFirst();
        SLLNode<Integer> prevX = null;
        SLLNode<Integer> prevY = null;

        if (d1 == null) {
            return;
        }

        if (x == y) {
            return;
        }

        while (dx != null && dx.element != x) {
            prevX = dx;
            dx = dx.succ;
        }
        while (dy != null && dy.element != y) {
            prevY = dy;
            dy = dy.succ;
        }

        if (dx != null && dy != null) {
            if (prevX != null) {
                prevX.succ = dy;
            } else {
                d1 = dy;
            }

            if (prevY != null) {
                prevY.succ = dx;
            } else {
                d1 = dx;
            }

            SLLNode<Integer> pom = dx.succ;
            dx.succ = dy.succ;
            dy.succ = pom;

        } else {
            System.out.println("Swapping not possible");
        }


        System.out.println(lista.toString());
    }