title: RecyclerView Q&A
body: <p>I'm creating a Q&amp;A where each question is a card.  The answer starts showing the first line, but when its clicked it should expanded to show the full answer.</p>
  
  <p>When an answer is expanded/collapsed the rest of the RecyclerView should animate to make room for the expansion or collapse to avoid showing a blank space.</p>
  
  <p>I watched the talk on <a href="https://www.youtube.com/watch?v=imsr8NrIAMs">RecyclerView animations</a>, and believe I want a custom ItemAnimator, where I override animateChange.  At that point I should create an ObjectAnimator to animate the height of the View's LayoutParams.  Unfortunately I'm having a hard time tying it all together. I also return true when overriding canReuseUpdatedViewHolder, so we reuse the same viewholder.</p>
  
  <pre><code>@Override
  public boolean canReuseUpdatedViewHolder(RecyclerView.ViewHolder viewHolder) {
      return true;
  }
  
  
  @Override
  public boolean animateChange(@NonNull RecyclerView.ViewHolder oldHolder,
                               @NonNull final RecyclerView.ViewHolder newHolder,
                               @NonNull ItemHolderInfo preInfo,
                               @NonNull ItemHolderInfo postInfo) {
      Log.d("test", "Run custom animation.");
  
      final ColorsAdapter.ColorViewHolder holder = (ColorsAdapter.ColorViewHolder) newHolder;
  
      FrameLayout.LayoutParams params = (FrameLayout.LayoutParams) holder.tvColor.getLayoutParams();
      ObjectAnimator halfSize = ObjectAnimator.ofInt(holder.tvColor.getLayoutParams(), "height", params.height, 0);
      halfSize.start();
      return super.animateChange(oldHolder, newHolder, preInfo, postInfo);
  }
  </code></pre>
  
  <p>Right now I'm just trying to get something to animate, but nothing happens...  Any ideas?</p>