expandable recyclerview update from firebase

Question

I'm using a expandable recyclerview in my project, the data is provided from a firebase consulting.

The expandable recyclerView that I use is: bignerdranch

What is the best way for update my view, because the site says:

Please note that the traditional notifyDataSetChanged() of RecyclerView.Adapter does not work as intended

and recommend use:

// Child Changes

notifyChildInserted(int parentPosition, int childPosition)

...

However, I don't know the childPositions that as changed.

Using a "click listener" you get the view, and the viewholder and the adapter position using library methods. If it is not a very long list, you can iterate from the first position to the clicked position (parent ? count=0 : count++), count is your childposition after the loop. If you check their code, youll find a place where they do the same. — albodelu, Mar 14 '17 at 23:23

score 0 · Answer 1 · edited May 23 '17 at 11:46

I'm not very proud of this solution, due to the loop, but this is an alternative for short lists:

You can get the clicked view from a listener, the viewHolder from the view and the adapter position from the view holder, finally use these methods:

Use this method

/**
 * Returns the adapter position of the Child associated with this ChildViewHolder
 *
 * @return The adapter position of the Child if it still exists in the adapter.
 * RecyclerView.NO_POSITION if item has been removed from the adapter,
 * RecyclerView.Adapter.notifyDataSetChanged() has been called after the last
 * layout pass or the ViewHolder has already been recycled.
 */
@UiThread
public int getChildAdapterPosition() {
    int flatPosition = getAdapterPosition();
    if (mExpandableAdapter == null || flatPosition == RecyclerView.NO_POSITION) {
        return RecyclerView.NO_POSITION;
    }

    return mExpandableAdapter.getChildPosition(flatPosition);
}

Also see

/**
 * Given the index relative to the entire RecyclerView for a child item,
 * returns the child position within the child list of the parent.
 */
@UiThread
int getChildPosition(int flatPosition) {
    if (flatPosition == 0) {
        return 0;
    }

    int childCount = 0;
    for (int i = 0; i < flatPosition; i++) {
        ExpandableWrapper<P, C> listItem = mFlatItemList.get(i);
        if (listItem.isParent()) {
            childCount = 0;
        } else {
            childCount++;
        }
    }
    return childCount;
}

An easy way to define the listener here.

ItemClickSupport.addTo(mRecyclerView).setOnItemClickListener(new ItemClickSupport.OnItemClickListener() {
    @Override
    public void onItemClicked(RecyclerView recyclerView, int position, View v) {
        // do it
    }
});

Use this to get the viewHolder:

@Override
public void onClick(View v) {
    MyHolder holder = (MyHolder) mRecyclerView.getChildViewHolder(v);
    holder.textView.setText("Clicked!");
}

Check the view type to know when the clicked view is a parent or a child

  //Returns the view type of the item at position for the purposes of view recycling.
  @Override
  public int getItemViewType(int position) {
      if (items.get(position) instanceof User) {
          return USER;
      } else if (items.get(position) instanceof String) {
          return IMAGE;
      }
      return -1;
  }

expandable recyclerview update from firebase

1 Answers1