Hollow Concentric Diamond with Numbers

This program prints hollow concentric diamonds using numbers.

Problem Statement

Write a Java program that prints concentric hollow diamonds with numbers up to 7 rows.

Source Code

1 public class HollowConcentricDiamondNumbers {
2 public static void main(String[] args) {
3 int n = 7;
4 for(int i=1; i<=n; i++) {
5 for(int j=i; j<n; j++) System.out.print(" ");
6 for(int j=1; j<=2*i-1; j++) {
7 if(j==1 || j==2*i-1) System.out.print(i);
8 else System.out.print(" ");
9 }
10 System.out.println();
11 }
12 for(int i=n-1; i>=1; i--) {
13 for(int j=i; j<n; j++) System.out.print(" ");
14 for(int j=1; j<=2*i-1; j++) {
15 if(j==1 || j==2*i-1) System.out.print(i);
16 else System.out.print(" ");
17 }
18 System.out.println();
19 }
20 }
21 }

Program Output

      1      
     2 2     
    3   3    
   4     4   
    5   5    
     6 6     
      7      

Explanation

The same hollow diamond boundary logic is used, but each row prints its own row index at the boundaries instead of a star, so the diamond edges are labeled with numbers reflecting their row position.

Quick Links to Explore