java，for循環嵌套，打印菱形

public class t8 {

    public static void main(String[] args) {
    //上半部分
        for (int m = 1; m <= 10; m++)
        {
            //輸出空格
            for (int n = 9; n >= m ;n--)
            {
                System.out.print(" ");
            }
            //輸出* 左上
            for (int n = 1; n <= m; n++)
            {
                System.out.print("*");
            }    
            
            //右上
            for (int n = 1; n < m; n++)
            {
                System.out.print("*");
            }

            System.out.println();
        }
        
        //下半部分
        for (int m = 1; m <= 9; m++)
        {
            //輸出空格
            for (int n = 1; n <= m ;n++)
            {
                System.out.print(" ");
            }
            //輸出* 左下
            for (int n = 9; n >= m; n--)
            {
                System.out.print("*");
            }    
            
            //右下
            for (int n = 9; n > m; n--)
            {
                System.out.print("*");
            }

            System.out.println();
        }    
}
}