Java Program to check if a Number/String is Palindrome

Palindrome number is a number which is equal to reverse of itself. For example 121 is a palindrome because reverse of 121 is 121, while 123 is not a palindrome in Java because reverse of 123 is 321 and 121!=321. 

Example:

To Check if a number is Palindrome:

import java.util.Scanner;

/**
 * Java program to check if number is palindrome or not.
 * A number is called palindrome if number and its reverse is equal
 * This Java program can also be used to reverse a number in Java
 */
public class PolyndromeExample{

    public static void main(String args[]){
       
        System.out.println("Please Enter a number : ");
        int palindrome = new Scanner(System.in).nextInt();
       
        if(isPalindrome(palindrome)){
            System.out.println("Number : " + palindrome + " is a palindrome");
        }else{
            System.out.println("Number : " + palindrome + " is not a palindrome");
        }          
    }
    /*
     * Java method to check if number is palindrome or not
     */
    public static boolean isPalindrome(int number) {
        int palindrome = number;
        int reverse = 0;

        while (palindrome != 0) {
            int remainder = palindrome % 10;
            reverse = reverse * 10 + remainder;
            palindrome = palindrome / 10;
        }

        if (number == reverse) {
            return true;
        }
        return false;
    }
}

To Check if a String is Palindrome:
A string is a palindrome if it remains unchanged when reversed, for example "dad" is a palindrome as reverse of "dad" is "dad" whereas "program" is not a palindrome.

import java.util.*;

 class Palindrome
{
   public static void main(String args[])
   {
      String original, reverse="";
      Scanner in = new Scanner(System.in);
 
      System.out.println("Enter a string to check if it is a palindrome");
      original = in.nextLine();
 
      int length = original.length();
 
      for ( int i = length - 1 ; i >= 0 ; i-- )
         reverse = reverse + original.charAt(i);
 
      if (original.equals(reverse))
         System.out.println("Entered string is a palindrome.");
      else
         System.out.println("Entered string is not a palindrome."); 
   }
}