code: public void update(byte[] b, int off, int len) {
          if (b == null) {
              throw new NullPointerException();
          }
          if (off < 0 || len < 0 || off > b.length - len) {
              throw new ArrayIndexOutOfBoundsException();
          }
          adler = updateBytes(adler, b, off, len);
      }
docs: Updates the checksum with the specified array of bytes.