public class Program {
    public static boolean isPalindrome(String str) {
        int start = 0;
        int end = str.length() - 1;
        while(start < end) {
            if(str.charAt(start) != str.charAt(end))
                return false;
            ++start;
            --end;
        }
        return true;
    }

    public static void main(String[] args) {
        System.out.println(isPalindrome("foobar"));
        System.out.println(isPalindrome("foof"));
        System.out.println(isPalindrome("abc 121 cba"));
    }
}