for (int i = 0; i < IMAGES_NUMBER_X * IMAGES_NUMBER_Y / 2; i++) {
imagesList.insertElementAt(new Integer(i), (int) (rand.nextFloat() *
(imagesList.size() + 1)));
imagesList.insertElementAt(new Integer(i), (int) (rand.nextFloat() *
(imagesList.size() + 1)));
}