Program to Find the Reverse of a Number in Java

Reversing a Number

The reverse of a number is obtained by extracting each digit and constructing a new number in reverse order.

We will explore a method to compute the reverse of a number using Java programming.

Method: Using a while Loop

We extract each digit using the modulus operator and build the reversed number.

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.print("Enter a number: ");
        int num = scanner.nextInt();
        int reversedNum = 0, digit;
        
        // Loop to extract and reverse digits
        while (num > 0) {
            digit = num % 10; // Extract last digit
            reversedNum = reversedNum * 10 + digit; // Construct reversed number
            num /= 10; // Remove last digit from number
        }
        
        // Print the result
        System.out.println("Reversed number = " + reversedNum);
        scanner.close();
    }
}
            

Output:

Enter a number: 1234
Reversed number = 4321