Palindrome number in Java using while loop

Sep 06, 2019 Examples, Loops, Problem Solving, Snippet comments

In this post we tackle another difficult program to solve that, is determining if a number is a palindrome. Below is the code to solve that. That is Determining Palindrome number in Java using while loop.

Palindrome number in Java using while loop

We build upon our logic in the previous post that reverses a number. After reversing a number, we then compare it with the original number to check if it is a palindrome or not. See example below:

/**
 * An example program that check if a number is a palindrome using while loop.
 */
public class ExampleProgram {
    public static void main(String[] args) {
        System.out.println(122 + " is a palindrome? : " + isPalindrome(122));
        System.out.println(121 + " is a palindrome? : " + isPalindrome(121));
        System.out.println(4555 + " is a palindrome? : " + isPalindrome(4555));
        System.out.println(45554 + " is a palindrome? : " + isPalindrome(45554));
    }
    public static boolean isPalindrome(int n) {
        // compare number with reverse
        return n == reverse(n);
    }
    public static int reverse(int n) {
        int reversedDigitNumber = 0;
        while( n > 0) {
            // extract last digit
            int digit = n % 10;
            // shift number and add digit to the right
            reversedDigitNumber = (reversedDigitNumber * 10) + digit;
            // remove the digit processed
            n = n / 10;
        }
        return reversedDigitNumber;
    }
}

And doing so will give the output below

122 is a palindrome? : false
121 is a palindrome? : true
4555 is a palindrome? : false
45554 is a palindrome? : true