How to check if word is palindrome using substrings instead of charAt?

===========================================================================

I just realized my mistake.

Instead of writing

        xvar = string.substring(i,i + 1);
        yvar = string.substring(count - 1 - i, count - i);

I wrote

        xvar = string.substring(i,i + 1);
        yvar = string.substring(count - 1 - i);

I was not aware that you had to "end" a substring, I used this answer. Considering the upvotes it has, I was wondering if someone could explain why it didn't work in my case . https://stackoverflow.com/a/40213223/14488701

==========================================================================

I was given an assignment that asks me to check if a word is a palindromes, but I am not allowed to use charAt.

This was the program I wrote using charAt

    import java.util.Scanner;
class Main{

    public static void main(String[] args)
    {
        Scanner scan = new Scanner(System.in);
        String a = scan.nextLine();
        a = a.replaceAll("\\s","");
        String string = a.toLowerCase();
        int count = string.length();
        int counter = 0;
        

        for (int i = 0; i < count; i++)
            if (string.charAt(i) != string.charAt(count - i - 1)) {
                System.out.print("");
                
            }
            else {
                
                counter++;
            }
        if (counter >= count) {
            System.out.println("This is a palindrome.");

        }
        else {
            System.out.println("This is not a palindrome.");

        }
    }
}

I am a bit confused on how to use substrings to solve this though.

This is what I tried so far. It does not work.

import java.util.Scanner;
class Main{

    public static void main(String[] args)
    {
        Scanner scan = new Scanner(System.in);
        String a = scan.nextLine();
        a = a.replaceAll("\\s","");
        String string = a.toLowerCase();
        int count = string.length();
        int counter = 0;
        String xvar = " ";
        String yvar = " ";
        for (int i = 0; i < count; i++) {
            xvar = string.substring(i, i + 1);
            yvar = string.substring(count - 1 - i);
            if (xvar.equals(yvar)){
                counter++;

            }
            else {
                System.out.print("");

            }
        }
        if (counter == count) {
            System.out.println("This is a palindrome.");

        }
        else {
            System.out.println("This is not a palindrome.");

        }
    }
}

So if I have the word pop and i =0, xvar would be "p", and yvar would also be "p".

for i=1, xvar would be "o", and yvar would also be "o".

For i =2 xvar would be "p" and yvar would also be "p".

Since there are 3 matches, I'm confused as to why I am getting the output "This is not a palindrome"

I was hoping someone could help my find my errors! Thanks.