public boolean fire(int r, int c) throws IOException { 
        if (1 > r || 1 > c || 10 < r || 10 < c) {
            invalidShot = true;
        } else {
            switch (board[r][c]) {
                case "x":
                case "!": return unavailibleShot();
                case "-": return missedShot(r, c);
                case "o": return hitShot(r, c);
            }
        } return false;
    }