輸入奇數-輸出鑽石型狀

public static void main(String args[]) {
        Scanner sca = new Scanner(System.in);
        System.out.print("請輸入一奇數：");
        int num = sca.nextInt();
        showDiamond(num);
    }

    public static void showDiamond(int num) {

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

        }
    }