Palindrome.java

import java.util.Scanner;

public class PalindromeChecker {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.print("Enter a string: ");
        String input = scanner.nextLine();
        
        if (isPalindrome(input)) {
            System.out.println(input + " is a palindrome.");
        } else {
            System.out.println(input + " is not a palindrome.");
        }
        
        scanner.close();
    }
    
    public static boolean isPalindrome(String str) {
        str = str.replaceAll("[^a-zA-Z0-9]", "").toLowerCase(); // Remove non-alphanumeric characters and convert to lowercase
        int left = 0;
        int right = str.length() - 1;
        
        while (left < right) {
            if (str.charAt(left) != str.charAt(right)) {
                return false; // If characters at the left and right pointers don't match, it's not a palindrome
            }
            left++;
            right--;
        }
        
        return true; // If we've reached this point, it's a palindrome
    }
}