Recursion

Here is a method that checks if the input string is a palindrome:

public static boolean isPalindrome(String s) {
    if (s.length() == 2 || s.length() == 1) { // (1)
        return true; // (2)
    }
        
    int lastIndex = s.length() - 1; // (3)
    boolean r = s.charAt(0) == s.charAt(lastIndex); // (4)
     
    return r || isPalindrome(s.substring(1, lastIndex)); // (5)
}

Unfortunately, the method is wrong. To fix it, you should change several lines of the code.

Choose the necessary whole line replacements.

Here are some tests with their expected results. The method should pass all tests.

isPalindrome(""); // true
isPalindrome("a"); // true
isPalindrome("aa"); // true
isPalindrome("ab"); // false
isPalindrome("aba"); // true
isPalindrome("abab"); // false
...