code: public void readObject (ObjectInputStream in)
          throws IOException, ClassNotFoundException
      {
          if (!classDefinesElementType()) {
              @SuppressWarnings("unchecked") Class<E> elementType =
                  (Class<E>)Class.forName(in.readUTF());
              _elementType = elementType;
  
          } else if (_elementType == null) {
              throw new RuntimeException("No element type defined in constructor.");
          }
          initContents();
          in.read(_contents);
  
          // count set bits to initialize size
          for (byte b : _contents) {
              _size += Integer.bitCount(b & 0xFF);
          }
      }
docs: Reads our custom streamable fields.