Java Program to Print Hollow Rhombus Star Pattern

In this article we are going to see how to print the Hollow Rhombus Star Pattern

Example-1

When row value=4
   ****
  *   *
 *   *
****

Example-2

When row value=5
    *****
   *    *
  *    *
 *    *
*****

Now, let’s see the actual program to print it.

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Approach:

Enter total row and store it in an integer variable rows.
Take one outer for loop to iterate the rows.
Take two inner for loops, one to print the space and the other one to print the star.
After each iteration print a new line.

JAVA Code:

Static Star Character
User Input Character

Method-1 : Static Star Character

import java.util.Scanner;
class pattern
{
    public static void main(String[] args)  
    {  
        Scanner scan = new Scanner(System.in);
        System.out.print("Rows : ");
        //Taking input from user
        int  rows=scan.nextInt();
        //Outer loop
        for (int r=1; r<=rows; r++)
        {//Inner loop 1
            for (int c=rows-1; c>=r; c--)
            {
                System.out.print(" ");
            }
            // Prints star in decreasing order
            for (int k=1; k<=rows; k++)
            {//Inner loop 2
                if (r == 1 || r == rows || k == 1 || k == rows)
                    System.out.print("*");
                else
                    System.out.print(" ");
            }
            //Prints a newline
            System.out.println();
        }  
    }  
}

Output:

Rows : 5
    *****
   *     *
  *     *
 *     *
*****

Method-2 : User Input Character

import java.util.Scanner;
class pattern
{
    public static void main(String[] args)  
    {  
        Scanner scan = new Scanner(System.in);
        System.out.print("Rows : ");
        //Taking input from user
        int  rows=scan.nextInt();
        
        System.out.print("Symbol : ");
        //Taking random character input from user
        char s=scan.next().charAt(0);
        
        //Outer loop
        for (int r=1; r<=rows; r++)
        {
            //Inner loop 1
            for (int c=rows-1; c>=r; c--)
            {
                System.out.print(" ");
            }
            // Prints star in decreasing order
            for (int k=1; k<=rows; k++)
            {
                //Inner loop 2
                if (r == 1 || r == rows || k == 1 || k == rows)
                    System.out.print(s);
                else
                    System.out.print(" ");
            }
            //Prints a newline
            System.out.println();
        }  
    }  
}

Output:

Rows : 5
Symbol : %
    %%%%%
   %         %
  %         %
 %         %
%%%%%

Explanation :

Let’s understand the program by going through the detailed explanation.

We have taken rows value as 5.

Iteration-1
r=1, goes into the first inner loop.

Now, c=rows-1 means 4. So prints 4 space as it will iterate upto c>=r.

The second for loop prints five star(‘*’) for r == 1 .

    *****

Iteration-2
r=2, goes into the first inner loop.

Now, c=rows-1 means 4. So prints 3 space as it will iterate upto c>=r

The second for loop prints one star(‘*’) for k ==1, then three space then another star(‘*’) for k == rows

   *   *

Iteration-3
r=3, goes into the first inner loop.

Now, c=rows-1 means 4. So prints 2 space as it will iterate upto c>=r

The second for loop prints one star(‘*’) for k ==1, then three space then another star(‘*’) for k == rows

  *   *

Iteration-4
r=4, goes into the first inner loop.

Now, c=rows-1 means 4. So prints 1 space as it will iterate upto c>=r.

The second for loop prints one star(‘*’) for k ==1, then three space then another star(‘*’) for k == rows

*   *

Iteration-5
r=5, does not go into first inner loop c>rows-1(i.e. c = 5).

Now, c=rows-1 means 4. So prints no space as it will iterate upto c>=r.

The second for loop prints five star(‘*’) for k == rows

*****

After this r >rows i.e. 6 so program will come out of the loop.

Now, after end of all iteration we will see the complete pattern is printed on the output screen like this.

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

C Code:

#include <stdio.h>
int main(int argc, char const *argv[])
{
    printf("Enter rows : ");
    int rows;
    //Taking row as input from user
    scanf("%d", &rows);
    //Outer loop
    for (int r = 1; r <= rows; r++)
    { //Inner loop
        for (int c = rows - 1; c >= r; c--)
        {
            printf(" ");
        }
        // Print stars in decreasing order
        for (int k = 1; k <= rows; k++)
        { //Inner loop 2
            if (r == 1 || r == rows || k == 1 || k == rows)
                printf("*");
            else
                printf(" ");
        } //To print a newline
        printf("\n");
    }
    return 0;
}

Output: 

Enter rows : 5     
    *****    
   *     *   
  *     *  
 *     * 
*****

C++ Code:

{
    cout << "Enter rows : ";
    int rows;
    //Taking row as input from user
    cin >> rows;
    //Outer loop
    for (int r = 1; r <= rows; r++)
    { //Inner loop 1
        for (int c = rows - 1; c >= r; c--)
        {
            cout << " ";
        }
        // Print stars in decreasing order
        for (int k = 1; k <= rows; k++)
        { //Inner loop 2
            if (r == 1 || r == rows || k == 1 || k == rows)
                cout << "*";
            else
                cout << " ";
        } //To print a newline
        cout << endl;
    }
    return 0;
}

Output: 

Enter rows : 5     
    *****    
   *     *   
  *     *  
 *     * 
*****

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