輸入奇數-沙漏形狀

    public static void main(String args[]) {

        Scanner sca = new Scanner(System.in);
        System.out.print("請輸入奇數：");
        int num = sca.nextInt();
        showHourglass(num);

    }

    public static void showHourglass(int num) {
        if (num % 2 == 0) {
            System.out.print("你輸入的不是奇數");
        } else {
            int mid = num / 2 + 1;
            // 上半部
            for (int i = mid; i > 0; i--) {
                for (int x = mid; x > i; x--)
                    System.out.print(" ");
                for (int x = 1; x < i * 2; x++)
                    System.out.print("X");
                System.out.println();
            }
            // 下半部
            for (int i = 2; i <= mid; i++) {
                for (int x = mid; x > i; x--)
                    System.out.print(" ");
                for (int x = 1; x < i * 2; x++)
                    System.out.print("X");
                System.out.println();
            }

        }

    }