# Java Program to Reverse a Number. Use Swing showInputDialog to get Input

The following program will accept a number through input dialog box and reverse it.

Procedure for Reversing a Number.

1. lastDigit=Modulus the given by 10

2. reverse = reverse * 10+lastDigit

3. Divide the number by 10

4. Continue the above steps until the given number becomes zero.

Consider the number 25 .

Reverse=0; // to store reversed number

Step 1 : 25 Mod 10 = 5

Step 2 : 25 / 10 = 2

Step 3 : Reverse=0*10+5 = 5

Now the number 25 becomes 2

Again Follow the above steps until the number becomes zero

Step 1 : 2 Mod 10 = 2

Step 2 : 2 / 10 = 0

Step 3 : Reverse=5*10+2 = 52

Now the value of Reverse is 52

// Code Begins

package com.javaonline; import javax.swing.JOptionPane; public class ReverseANumber { public static void main(String [] args){ try{ String input = JOptionPane.showInputDialog("Enter any number: "); // Displays Input Dialog Box to enter number int num= Integer.parseInt(input); // converts string to number int orgNum=num; int rev=0; while(num>0) { int d=num%10; num=num/10; rev=rev*10+d; } System.out.println("Reverse("+orgNum+ ") = "+ rev); } catch(Exception e){ System.out.println("Please enter Integer!"); } } }

Run the program

Give number as 12345 in the input dialog box