public void swapHunter() {
        field[swapper_y][swapper_x] = "hunter";
        field[hunter_y][hunter_x] = "swapper";
        
        int tmp = swapper_x;
        swapper_x = hunter_x;
        hunter_x = tmp;
        
        tmp = swapper_y;
        swapper_y = hunter_y;
        hunter_y = tmp;
    }