Java Program to Print a Cross (X) Pattern

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Introduction

Printing an X pattern is a fun programming exercise that involves controlling the placement of characters based on their row and column indices. This guide will walk you through writing a Java program that prints an X pattern using stars (*), where the diagonal elements form the shape of the X.

Problem Statement

Create a Java program that:

• Accepts the size (number of rows and columns) of the X pattern.
• Prints an X pattern where stars (*) are placed on both diagonals and spaces are placed elsewhere.

Example:

• Input: 5

• Output:

  *   *
   * * 
    *  
   * * 
  *   *
  

• Input: 7

• Output:

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

Solution Steps

1. Take Input: Accept the size of the X pattern (must be an odd number for symmetry).
2. Print the X Pattern: Use nested loops to print stars (*) for diagonal positions and spaces elsewhere.
3. Display the Result: Print the X pattern on the console.

Java Program

// Java Program to Print a Cross (X) Pattern
// Author: https://www.rameshfadatare.com/

import java.util.Scanner;

public class CrossPattern {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        // Step 1: Get the size of the pattern
        System.out.print("Enter the size of the X pattern (odd number): ");
        int size = scanner.nextInt();

        // Step 2: Loop through each row
        for (int i = 0; i < size; i++) {
            // Step 3: Loop through each column in the row
            for (int j = 0; j < size; j++) {
                // Step 4: Print '*' on the diagonals, otherwise print ' '
                if (j == i || j == (size - i - 1)) {
                    System.out.print("*");
                } else {
                    System.out.print(" ");
                }
            }
            // Move to the next line after printing each row
            System.out.println();
        }

        // Close the scanner
        scanner.close();
    }
}

Explanation

Step 1: Take Input

• The program asks the user for the size of the X pattern. The size must be an odd number to create a symmetric X pattern.

Step 2: Loop Through Each Row

• A for loop iterates from 0 to size - 1, where each iteration corresponds to one row of the pattern.

Step 3: Loop Through Each Column

• For each row, a nested for loop iterates from 0 to size - 1 to print the elements in that row.

Step 4: Print Stars (*) on the Diagonals

• The condition j == i prints a star on the primary diagonal (top-left to bottom-right).
• The condition j == (size - i - 1) prints a star on the secondary diagonal (top-right to bottom-left).
• Elsewhere, spaces (" ") are printed.

Output Example

For an input of 5, the program outputs:

*   *
 * * 
  *  
 * * 
*   *

For an input of 7, the program outputs:

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

Example with Different Input

For an input of 3, the program outputs:

* *
 * 
* *

Conclusion

This Java program demonstrates how to print an X pattern using nested loops. By carefully controlling the conditions for printing stars (*) on both diagonals, the program efficiently creates the desired cross shape. This exercise is a great way to practice using loops and conditionals in Java programming for pattern generation.