code: public <T extends View> T findViewByIdEfficient(int parentId, int id) {
          View viewRetrieve = retrieveFromCache(parentId, id);
          if (viewRetrieve == null) {
              viewRetrieve = findViewById(parentId, id);
              if (viewRetrieve != null) {
                  storeView(parentId, id, viewRetrieve);
              }
          }
          return castView(viewRetrieve);
      }
docs: Look for a child view of the parent view id with the given id.  If this view has the given
  id, return this view.
  The method is more efficient than a "normal" "findViewById" : the second time you will
  called this method with the same argument, the view return will come from the cache.
  
  @param id The id to search for.
  @return The view that has the given id in the hierarchy or null