public char charAt(int position){
  if (s != null && position >= 0 && position < s.length()) {
    return s.charAt(position);
  }
  return 0;
}

public char charAt ( int position ) { if ( s != null && position >= 0 && position < s . length ( ) ) { return s . charAt ( position ) ; } return 0 ; }
get the char by the absolute position
