code: public void select(boolean considerSelectableFlag) {
          SelectExtension<Item> selectExtension = mFastAdapter.getExtension(SelectExtension.class);
          if (selectExtension == null) {
              return;
          }
          for (Item item : AdapterUtil.getAllItems(mFastAdapter)) {
              selectExtension.select(item, considerSelectableFlag);
          }
          mFastAdapter.notifyDataSetChanged();
      }
docs: select all items
  
  @param considerSelectableFlag true if the select method should not select an item if its not selectable