Java Program to Print Alphabet O Pattern

In this Java pattern program, we show the steps to print the stars in an Alphabet O shape or pattern using for loop, while loop, and functions.

import java.util.Scanner;

public class Example 
{
	private static Scanner sc;
	
	public static void main(String[] args) 
	{
		sc = new Scanner(System.in);
		
		System.out.print("Enter Rows = ");
		int rows = sc.nextInt();

		for (int i = 0; i < rows; i++) 
		{
			for (int j = 0; j <= rows; j++) 
			{
				if(((i == 0 || i == rows - 1) && (0 < j && j < rows - 1)) || 
						((j == 0 || j == rows - 1) && (0 < i && i < rows - 1)))
				{
					System.out.printf("*");
				} 
				else 
				{
					System.out.printf(" ");
				}
			}
			System.out.println();
		}
	}
}

Enter Rows = 15
 *************  
*             * 
*             * 
*             * 
*             * 
*             * 
*             * 
*             * 
*             * 
*             * 
*             * 
*             * 
*             * 
*             * 
 *************  

Within this Alphabet O shape or Pattern program, we replaced the for loop with a while loop to print the stars at each position. For more Alphabet Patterns and star pattern programs, please use the hyperlinks.

import java.util.Scanner;

public class Example 
{
	private static Scanner sc;
	
	public static void main(String[] args) 
	{
		sc = new Scanner(System.in);
		int rows, i, j;
		
		System.out.print("Enter Rows = ");
		rows = sc.nextInt();

		i = 0;
		while ( i < rows) 
		{
			j = 0;
			while ( j <= rows) 
			{
				if((i == 0 || i == rows - 1) && (0 < j && j < rows - 1))
				{
					System.out.printf("*");
				}
				else if ((j == 0 || j == rows - 1) && (0 < i && i < rows - 1))
				{
					System.out.printf("*");
				}
				else 
				{
					System.out.printf(" ");
				}
				j++;
			}
			System.out.println();
			i++;
		}
	}
}

Enter Rows = 17
 ***************  
*               * 
*               * 
*               * 
*               * 
*               * 
*               * 
*               * 
*               * 
*               * 
*               * 
*               * 
*               * 
*               * 
*               * 
*               * 
 ***************  

In this program, we created an AlphabetOShape function to print the Alphabet O Pattern or pattern filled with stars on rows and columns.

import java.util.Scanner;

public class Example 
{
	private static Scanner sc;
	
	public static void main(String[] args) 
	{
		sc = new Scanner(System.in);
		
		System.out.print("Enter Rows = ");
		int rows = sc.nextInt();

		System.out.print("Enter Character = ");
		char a = sc.next().charAt(0);

		AlphabetOShape(rows, a);
	}
	
	public static void AlphabetOShape(int rows, char a) 
	{
		for (int i = 0; i < rows; i++) 
		{
			for (int j = 0; j <= rows; j++) 
			{
				if(((i == 0 || i == rows - 1) && (0 < j && j < rows - 1)) || 
						((j == 0 || j == rows - 1) && (0 < i && i < rows - 1)))
				{
					System.out.printf("%c", a);
				} 
				else 
				{
					System.out.printf(" ");
				}
			}
			System.out.println();
		}
	}
}