View createSectionHeaderIfNeeded(RecyclerView.Recycler recycler,int sectionIndex){
  if (adapter.doesSectionHaveHeader(sectionIndex)) {
    for (int i=0, n=getChildCount(); i < n; i++) {
      View view=getChildAt(i);
      if (getViewBaseType(view) == SectioningAdapter.TYPE_HEADER && getViewSectionIndex(view) == sectionIndex) {
        return view;
      }
    }
    int headerAdapterPosition=adapter.getAdapterPositionForSectionHeader(sectionIndex);
    View headerView=recycler.getViewForPosition(headerAdapterPosition);
    headerViews.add(headerView);
    addView(headerView);
    measureChildWithMargins(headerView,0,0);
    return headerView;
  }
  return null;
}

View createSectionHeaderIfNeeded ( RecyclerView . Recycler recycler , int sectionIndex ) { if ( adapter . doesSectionHaveHeader ( sectionIndex ) ) { for ( int i = 0 , n = getChildCount ( ) ; i < n ; i ++ ) { View view = getChildAt ( i ) ; if ( getViewBaseType ( view ) == SectioningAdapter . TYPE_HEADER && getViewSectionIndex ( view ) == sectionIndex ) { return view ; } } int headerAdapterPosition = adapter . getAdapterPositionForSectionHeader ( sectionIndex ) ; View headerView = recycler . getViewForPosition ( headerAdapterPosition ) ; headerViews . add ( headerView ) ; addView ( headerView ) ; measureChildWithMargins ( headerView , 0 , 0 ) ; return headerView ; } return null ; }
get the header item for a given section , creating it if it ' s not already in the view hierarchy
