Java Program to Reverse a Number

In this post you will learn basic java program that reverses the digits of a number and print the reversed number.

Problem:

Here is the example of the problem –

Example 1:

Input : 5678
Output :8765

Example 2:

Solutions:

• First, we find the remainder of the given number by using the modulo (%) operator.
• Multiply the variable reverse by 10 and add the remainder into it.
• Divide the number by 10.

There are three ways to reverse a number in java:

• Reverse a number using while loop.
• Reverse a number using for loop.
• Reverse a number using recursion.

Approach 1 :  Reverse a number using loops

public class ReverseNumber   
{  
public static void main(String[] args)   
{  
int number = 12345, reverse = 0;  
while(number != 0)   
{  
int remainder = number % 10;  
reverse = reverse * 10 + remainder;  
number = number/10;  
}  
System.out.println("The reverse of the given number is: " + reverse);  
}  
}

Output:

The reverse of the given number is: 54321

Approach 2 :  Reverse a number using recursion:

import java.util.Scanner;  
public class ReverseNumber 
{  
//method for reverse a number  
public static void reverseNumber(int number)   
{  
if (number < 10)   
{  
//prints the same number if the number is less than 10  
System.out.println(number);  
return;  
}  
else   
{  
System.out.print(number % 10);  
reverseNumber(number/10);  
}  
}  
public static void main(String args[])  
{  
System.out.print("Enter the number that you want to reverse: ");  
Scanner sc = new Scanner(System.in);  
int num = sc.nextInt();  
System.out.print("The reverse of the given number is: ");  
//method calling  
reverseNumber(num);  
}  
}  

Output:

Enter the number that you want to reverse: 1413
The reverse of the given number is: 3141

More java programs:

Java Program to Print Multiplication Table of a Number

Java Program to Get Input from User

Java Program to Count Number of Digits in a Number