How to reverse a number in Java

Reverse a number/Integer

We can reverse a number by converting it into a String or iteratively or recursively.

Now we will how to reverse  number by converting it into a String.

package com.interviewCodes.String;

public class ReverseNumberDemo1 {

      

       public static void main(String[] args) {

              int num=12456;

              //converting Integer into a String

              String str=String.valueOf(num);

              //Now we can reverse the String as shown in my previous post

              //And then convert that String into Integer like below

              Integer revNum=Integer.parseInt(str);

       }

}

We can reverse the Number by iteratively or recursively as below:

package com.interviewCodes.String;

import java.util.Scanner;

public class ReverseNumberDemo{

       public static void main(String[] args) {

               

         int num, reverseNum = 0;

      System.out.println("Enter the number to reverse");

      Scanner in = new Scanner(System.in);

      num = in.nextInt();

      //reverse a number iteratively

      reverseNum=reverseIteratievly(num);

      System.out.println("Reverse a number Iteratively : "+reverseNum);

      //reverse a number recursively

      reverseNum=reverseRecursievly(num);

      System.out.println("Reverse a number Iteratively : "+reverseNum);

    }

       public static int reverseIteratievly(int num) {

              int reverse=0;

           while( num != 0 )

             {

                 reverse = reverse * 10;

                 reverse = reverse + num%10;

                 num = num/10;

             }

             return reverse;

       }

    public static int  reverseRecursievly(int num) {

             

       return _reverseRecurievly(num,0);

     }

     public static int _reverseRecurievly(int n,int r){

       if(n==0){

              return r;

       }

       else{

              return _reverseRecurievly(n/10,r*10+n%10);

       }

}

}

That's all about reverse a number.If any other ways are there to reverse a number,please comment.Thanks for reading.