public void update(Ship ship ,int delta) {
    if (state == States.MISSILE) {
      setX(getX() - delta * speed);
      anims[States.MISSILE.ordinal()].update(delta);
      check_collisions(ship);
    } else if (state == States.EXPLOSION) {
      if (anims[States.EXPLOSION.ordinal()].is_stopped()) {
        state = States.DESTROY;
      }
    }
  }