public static void advanceAll(ArrayList<Animal> animals) { ArrayList<Scorpion> scorps = new ArrayList<Scorpion>(); for (Animal a : animals) { a.advance(); if (a.getClass() == Scorpion.class) { scorps.add((Scorpion) a); } } for (Scorpion s : scorps) { if (s.unluckyFellow != -1) { System.out.println(animals.get(s.unluckyFellow).getName() + " has been stung!"); animals.remove(s.unluckyFellow); } } }