Java Program to Print Hollow Diamond Star Pattern

• Java program to print hollow diamond star pattern using for loop.

Sample Output,

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

Java program to print hollow diamond star pattern

package com.tcc.java.programs;

import java.util.Scanner;

public class HollowDiamond {
    public static void main(String[] arg) {
        int rows, i, space, star = 0;
        Scanner scanner = new Scanner(System.in);
        System.out.println("Enter Number of Rows of Hollow Diamond Pattern");
        rows = scanner.nextInt();
        /* PRINTING UPPER TRIANGLE */
        // printing one row in every iteration
        for (i = 1; i <= rows; i++) {
            // Printing spaces
            for (space = 1; space <= rows - i; space++) {
                System.out.print(" ");
            }
            // Printing stars
            while (star != (2 * i - 1)) {
                // Print only the first and last star of row
                if (star == 0 || star == (2 * i - 2))
                    System.out.print("*");
                else
                    System.out.print(" ");
                star++;
            }
            star = 0;
            // move to next row
            System.out.print("\n");
        }
        rows--;
        /* PRINTING LOWER TRIANGLE */
        for (i = rows; i >= 1; i--) {
            /* Printing spaces */
            for (space = 0; space <= rows - i; space++) {
                System.out.print(" ");
            }
            /* Printing stars */
            star = 0;
            while (star != (2 * i - 1)) {
                // Print only the first and last star of row
                if (star == 0 || star == (2 * i - 2))
                    System.out.print("*");
                else
                    System.out.print(" ");
                star++;
            }
            System.out.print("\n");
        }
    }
}

Output

Enter Number of Rows of Hollow Diamond Pattern
7
      *
     * *
    *   *
   *     *
  *       *
 *         *
*           *
 *         *
  *       *
   *     *
    *   *
     * *
      *