Java Program To Reverse a Number using While Loop

In this Java Program, we reverse a number using while loop.

Logic :

  while (num != 0)

             {

                reversenum = reversenum * 10;

                reversenum = reversenum + num%10;

                num = num/10;                

             }

Step 1 : Import the Scanner Class

Step 2 :  Create the main method

Step 3 : Initialize num and reversenum equals to zero

Step 4 : Ask the user to enter the number by using System.out.println() method

Step 5 : Create Scanner object.

Step 6 : Store the captured input in num

Step 7 : Apply while loop logic to reverse the number

Step 8 : In while loop, num should be not equal to zero

Step 9 : Multiply reversenum with 10 and store its result in reversenum.

Step 10 : Add num%10 to reversenum and store the result into reversenum

Step 11 : Divide num by 10 and store the result in num.

Step 12 : Print the reversenum

Program :

import java.util.Scanner;

public class ReverseNumberWhile 

    {

        public static void main(String args[])

        {

            int num =0;

            int reversenum = 0;

            System.out.println("Input your number and press enter:");

            //This statement will capture the user input

            Scanner sc = new Scanner(System.in);

            //Captured input would be stored in number num

            num = sc.nextInt();

            //While loop: Logic to find out the reverse number

            while (num != 0)

             {

                reversenum = reversenum * 10;

                reversenum = reversenum + num%10;

                num = num/10;                

             }

            System.out.println("Reverse of input number is : "+reversenum);

        }

}