输出由"*"构成的棱形

public class Graph {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        System.out.println("输入一个数：");
        int n = sc.nextInt();
        //菱形 method 1
        for (int i = 0; i < 4; i++) {
            for (int j = 0; j < 3 - i; j++)
                System.out.print(" ");
            for (int j = 0; j < 2 * i + 1; j++)
                System.out.print("*");
            System.out.println();
        }
        for (int i = 0; i < 4; i++) {
            for (int j = 0; j < i + 1; j++)
                System.out.print(" ");
            for (int j = 0; j < 5 - 2 * i; j++)
                System.out.print("*");
            System.out.println();
        }

棱形输出方法二：调用库中数学方法Math.abs();

//以中心最长的行数为i=0;向上的行数为-1，-2，向下为正号
for (int i = -n; i < n; i++) {
            for (int j = 0; j < Math.abs(i) + 1; j++)
                System.out.print(" ");
            for (int j = 0; j <( n+1) - 2 * Math.abs(i); j++)//调用绝对值函数
                System.out.print("*");
            System.out.println();
        }

运行结果如下：

image.png
image.png