Java Program to Reverse a Number

In this article, we will understand how to print an integer in Java. The reverse of a number is computed using a loop and arithmetic operator % and /.

Below is a demonstration of the same −

Input

Suppose our input is −

The number : 123456

Output

The desired output would be −

The result is 654321

Algorithm

Step 1 - START
Step 2 - Declare three integer values namely my_input, reverse_input and remainder.
Step 3 - Read the required values from the user/ define the values
Step 4 – Run a while loop
Step 5- Use modulus of 10 and get remainder for ‘my_remainder’ .
Step 6- Multiply ‘reverse_input’ with 10, and add to ‘my_remainder’, and make that the
current ‘reverse_input’.
Step 7- Divide ‘my_input’ by 10, and make that the current ‘my_input.
Step 8- Display the result
Step 9- Stop

Example 1

Here, the input is being entered by the user based on a prompt. You can try this example live in ourcoding ground tool .

import java.util.Scanner;
public class ReverseNumber{
   public static void main(String[] args){
      int my_input , reverse_input, my_remainder;
      reverse_input = 0;
      System.out.println("Required packages have been imported");
      Scanner my_scanner = new Scanner(System.in);
      System.out.println("A reader object has been defined ");
      System.out.print("Enter the number : ");
      my_input = my_scanner.nextInt();
      while(my_input != 0){
         my_remainder = my_input % 10;
         reverse_input = reverse_input * 10 + my_remainder;
         my_input = my_input/10;
      }
      System.out.println("The reverse value of the given input is: " + reverse_input);
   }
}

Output

Required packages have been imported
A reader object has been defined
Enter the number : 123456
The reverse value of the given input is: 654321

Example 2

Here, the integer has been previously defined, and its value is accessed and displayed on the console.

public class ReverseNumber{
   public static void main(String[] args){
      int my_input , reverse_input;
      my_input = 123456;
      reverse_input = 0;
      System.out.println("The number is defined as " +my_input);
      while(my_input != 0){
         int remainder = my_input % 10;
         reverse_input = reverse_input * 10 + remainder;
         my_input = my_input/10;
      }
      System.out.println("The reverse value of the given input is: " + reverse_input);
   }
}

Output

The number is defined as 123456
The reverse value of the given input is: 654321