public class Palindrome {

    public static void main (String[] argv)
    {
        String str = "redder";
        System.out.println ( str + " " + checkPalindrome(str,0) );

        str = "river";
        System.out.println ( str + " " + checkPalindrome(str,0) );

        str = "neveroddoreven";
        System.out.println ( str + " " + checkPalindrome(str,0) );
    }
    

    static String checkPalindrome (String str, int level)
    {
        // Two bottom out cases:
        if ( (str.length() == 0) || (str.length() == 1) ) {
            return "is a palindrome";
        }
        if ( str.charAt(0) != str.charAt(str.length()-1) ) {
            return "is not a palindrome";
        }

        // First and last letters matched. Remove them and check remaining recursively.
        String nextStr = str.substring (1, str.length()-1);

        return checkPalindrome (nextStr, level+1);
    }

}