The document discusses the implementation details of RecyclerView, covering topics such as the differences between ListView and LinearLayout, as well as Adapter, ItemDecoration, ItemAnimator, and LayoutManager. It provides code snippets for creating and managing these components in Android development. Additionally, it includes a Q&A section for clarification on the covered topics.

1. ©2015 GlobalLogic Inc. CONFIDENTIAL

2. ©2015 GlobalLogic Inc. CONFIDENTIAL
RecyclerView

3. CONFIDENTIAL
Agenda
1. ListView vs LinearLayout
2. Adapter
3. ItemDecoration
4. ItemAnimator
5. LayoutManager
6. Q&A

4. CONFIDENTIAL©2015 GlobalLogic Inc.
ListView vs LinearLayout

5. CONFIDENTIAL
ListView vs LinearLayout
LinearLayout ListView

6. CONFIDENTIAL©2015 GlobalLogic Inc.
Adapter

7. CONFIDENTIAL
RecyclerView.Adapter<ViewHolder>
@Override
public int getItemCount() {
return mData.size();
}
@Override
public ViewHolder onCreateViewHolder(ViewGroup viewGroup, int viewType) {
View view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.item_layout, viewGroup, false);
// initializing view’s listeners
return new ViewHolder(view);
}
@Override
public void onBindViewHolder(ViewHolder viewHolder, int position) {
viewHolder.update(mData.get(position));
}

8. CONFIDENTIAL©2015 GlobalLogic Inc.
ItemDecoration

9. CONFIDENTIAL
RecyclerView.ItemDecoration
Item #2
Item #1
Item #2
Item #1
Item #2
Item #1
@Override
public void onDraw(Canvas canvas, RecyclerView parent, RecyclerView.State state) {
// drawing under the views
}
@Override
public void onDrawOver(Canvas canvas, RecyclerView parent, RecyclerView.State state) {
// drawing over the views
}
@Override
public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
// adding extra paddings to the view
}

10. CONFIDENTIAL©2015 GlobalLogic Inc.
ItemAnimator

11. CONFIDENTIAL
RecyclerView.ItemAnimator
● DefaultItemAnimator
● Call notifyItemXXXX() instead of notifyDataSetInvalidated()
● Custom ItemAnimator

12. CONFIDENTIAL
RecyclerView.ItemAnimator
Custom ItemAnimator:
● animateXXXX()
● runPendingAnimations()
● endAnimation(), endAnimations()
*do not forget to call dispatchXXXFinished()

13. CONFIDENTIAL
RecyclerView.ItemAnimator
public boolean animateAdd(final ViewHolder holder) {
endAnimation(holder);
mPendingAdditions.add(holder);
return true;
}
public void runPendingAnimations() {
...
if (!mPendingAdditions.isEmpty()) {
final ArrayList<ViewHolder> additions = new ArrayList<ViewHolder>();
additions.addAll(mPendingAdditions);
mAdditionsList.add(additions);
mPendingAdditions.clear();
for (ViewHolder holder : additions) {
animateAddImpl(holder);
}
additions.clear();
mAdditionsList.remove(additions);
}
}

14. CONFIDENTIAL©2015 GlobalLogic Inc.
LayoutManager

15. CONFIDENTIAL
RecyclerView.LayoutManager
Predefined LayoutManagers:
● LinearLayoutManager: horizontal and vertical
● StaggeredGridLayoutManager
● GridLayoutManager
● Custom LayoutManager

16. CONFIDENTIAL
RecyclerView.LayoutManager
Custom LayoutManager:
● generateDefaultLayoutParams()
● onLayoutChildren()
● canScrollHorizontally() & canScrollVertically()
● scrollHorizontallyBy() & scrollVerticallyBy()
● offsetChildrenHorizontal() & offsetChildrenVertical()
● layoutDecorated(), getDecoratedXXXX()

17. CONFIDENTIAL
RecyclerView.LayoutManager
A BB C D E
Remove item animation:
A C D E F

18. CONFIDENTIAL
RecyclerView.LayoutManager
● supportsPredictiveItemAnimations()
● onLayoutChildren()
● RecyclerView.State.isPreLayout()
● LayoutParams.isItemRemoved()
Remove item animation:
A B C D E FA FC D E

19. CONFIDENTIAL
RecyclerView.LayoutManager
Insert item animation:
A B C D EA B C DX

20. CONFIDENTIAL
RecyclerView.LayoutManager
● getScrapList()
● addDisappearingView() instead of addView()
Insert item animation:
A B C D EA EB C DX

21. CONFIDENTIAL©2015 GlobalLogic Inc.
Q&A

22. CONFIDENTIAL©2015 GlobalLogic Inc.
Alexander Kravchenko
Thank You!