Palindrome Program in Java: Number is Palindrome or Not

Published December 23, 2020

What is a Palindrome Number?

A palindromic number is actually just a number that remains exactly the same when its digits are reversed. Quite simply, it's reflectional symmetry around a perpendicular axis. The expression palindromic is based on a palindrome, which describes to some note whose text is more unchanged if its own characters have been now reversed.

Algorithm for String Palindrome Program in Java

Take input from a user and store it in any variable.
Now copy the same number and store it in the temporary variable.
Reverse the temporary variable.
Compare the value of the temporary variable with the original string or number.
If they both are the same then print that the number is a palindrome.
If not then print that the number is not a palindrome.

Program to check whether the String is Palindrome or Not

import java.util.Scanner;
class palindromeString

{
public static void main(String args[])

{
      String str, rev = "";

     Scanner sc = new Scanner(System.in);

     System.out.println("Enter a string:");

     str = sc.nextLine();

     int length = str.length();

     for ( int i = length - 1; i >= 0; i-- )

        rev = rev + str.charAt(i);

     if (str.equals(rev))
        System.out.println(str+" is a palindrome");

     else
        System.out.println(str+" is not a palindrome");
   }

}

Output:

Enter a string:

NITIN

NITIN is a palindrome

Program to check whether the Input Number is Palindrome or Not

public class PalindromeNumber {

public static void main(String[] args)

{
int lastDigit,sum=0,a;

int originalNumber=252; //The number you want to check whether it is palindrome or not

a=originalNumber;
// Code to reverse a number

while(a>0)

{ System.out.println("Original Number "+a);

lastDigit=a%10; //get remainder

System.out.println("Last Digit "+lastDigit);

System.out.println("Digit "+lastDigit+ " added in sum "+(sum*10));

sum=(sum*10)+lastDigit;

a=a/10;
}

// if given number equal to sum than number is palindrome otherwise not palindrome

if(sum==originalNumber)

System.out.println("Number is palindrome ");

else

System.out.println("Number is not palindrome");

}

}

Output

Original Number: 252

Last digit: 2

Digit 2 added in sum 0

Original Number: 25

Last digit: 5

Digit 2 added in sum 20

Original Number: 2

Last digit: 2

Digit 2 added in sum 250

Number is Palindrome

Palindrome In Java

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