用java打印空心菱形

以下是用Java打印空心菱形的代码：

import java.util.Scanner;

public class HollowDiamond {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        System.out.print("Enter the number of rows: ");
        int rows = sc.nextInt();

        for (int i = 1; i <= rows; i++) {
            for (int j = i; j < rows; j++) {
                System.out.print(" ");
            }

            for (int k = 1; k <= i * 2 - 1; k++) {
                if (k == 1 || k == i * 2 - 1) {
                    System.out.print("*");
                } else {
                    System.out.print(" ");
                }
            }

            System.out.println();
        }

        for (int i = rows - 1; i >= 1; i--) {
            for (int j = rows; j > i; j--) {
                System.out.print(" ");
            }

            for (int k = 1; k <= i * 2 - 1; k++) {
                if (k == 1 || k == i * 2 - 1) {
                    System.out.print("*");
                } else {
                    System.out.print(" ");
                }
            }

            System.out.println();
        }
    }
}

运行结果：

Enter the number of rows: 5
        *
       * *
      *   *
     *     *
    *       *
     *     *
      *   *
       * *
        *