code: boolean isZero(String s) {
              char[] cs = s.toCharArray();
              int base = ((cs.length > 1 && Character.toLowerCase(cs[1]) == 'x') ? 16 : 10);
              int i = ((base==16) ? 2 : 0);
              while (i < cs.length && (cs[i] == '0' || cs[i] == '.')) i++;
              return !(i < cs.length && (Character.digit(cs[i], base) > 0));
          }
docs: where