Java语言编写菱形，四行代码实现

 通过StringUtils工具类实现

public class Rhombus {
    public static void main(String[] args) {
        for (int i = 1; i <= 21; i += 4)
            System.out.println(StringUtils.center("*".repeat(i), 21));
        for (int i = 17; i >= 1; i -= 4)
            System.out.println(StringUtils.center("*".repeat(i), 21));
    }
}

 运行结果如下

          *          
        *****        
      *********      
    *************    
  *****************  
*********************
  *****************  
    *************    
      *********      
        *****        
          *          

Process finished with exit code 0

附带for循环实现的空心菱形

public class HollowRhombus {
    public static void main(String[] args) {
        int l = 11;
        for (int i = 0; i < 6; i++) {
            for (int j = 0; j < l; j++) {
                System.out.print(" ");
            }
            l-=2;
            for (int j = 0; j <= i*4+1; j++) {
                if(j==1||j==i*4+1)System.out.print("*");
                else System.out.print(" ");
            }
            System.out.println();
        }
        l=3;
        for (int i = 5; i > 0; i--) {
            for (int j = 0; j < l; j++) {
                System.out.print(" ");
            }
            l+=2;
            for (int j = 0; j <= (i-1)*4+1; j++) {
                if(j==1||j==(i-1)*4+1)System.out.print("*");
                else System.out.print(" ");
            }
            System.out.println();
        }
    }
}

 运行结果如下

            *
          *   *
        *       *
      *           *
    *               *
  *                   *
    *               *
      *           *
        *       *
          *   *
            *

Process finished with exit code 0