Architecture-components-samples: PagedListAdapter with multiple ViewHolders scroll bug
Hello,
I tried to add custom header (as a separeated ViewHolder) to the RecyclerView with PagedListAdapter but in that configuration loadInitial() (from DataSource) will caused automaticall scroll to the end of the loaded page (and it will trigger next load with loadRange()). This behaviour can be easily reproduced by changing this line from PostAdapter in PagingWithNetworkSample: private fun hasExtraRow() = true // networkState != null && networkState != NetworkState.LOADED.
I assume it is caused by wrong insertion notification from AsyncPagedListDiffer. Position on the data list is not the same as in the adapter because there I have one extra item.
How can I handle correctly this situation? Maybe some method in PagedListAdapter to calculate real data position would be helpful.
kamgurgul
All 9 comments
You're right about the insert notification - If you want items above the PagedListAdapter, switch to using AsyncPagedListDiffer, and pass a custom ItemCallback that offsets the positions by one:
final AdapterListUpdateCallback adapterCallback
= new AdapterListUpdateCallback(/*Adapter*/ this);
new AsyncPagedListDiffer<>(new ListUpdateCallback() {
@Override
public void onInserted(int position, int count) {
adapterCallback.onInserted(position + 1, count);
}
@Override
public void onRemoved(int position, int count) {
adapterCallback.onRemoved(position + 1, count);
}
@Override
public void onMoved(int fromPosition, int toPosition) {
adapterCallback.onMoved(fromPosition + 1, toPosition + 1);
}
@Override
public void onChanged(int position, int count, Object payload) {
adapterCallback.onChanged(position + 1, count, payload);
}
}, config);
ChrisCraik
on 25 May 2018
👍11
❤4
👎1
Working like a charm. I missed that overload.
Thank you.
kamgurgul
on 25 May 2018
👍2
Hi guys @kamgurgul @ChrisCraik , I am having this problem too and I don't know how to solve it, could anyone help me with the code ?
I get the list automatically scrolled to the end of the loaded page.
I have this adapter with this three ViewHolders:
public class HomeAdapter extends PagedListAdapter<HomeItem, RecyclerView.ViewHolder> {
private NetworkState networkState;
private RetryCallback retryCallback;
private RecommendedAdapter recommendedAdapter;
@Inject
public HomeAdapter() {
super(feedDiffUtil);
}
public void setRetryCallback(RetryCallback retryCallback) {
this.retryCallback = retryCallback;
}
public void setRecommendedAdapter(RecommendedAdapter recommendedAdapter) {
this.recommendedAdapter = recommendedAdapter;
}
@NonNull
@Override
public RecyclerView.ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
switch (viewType) {
case R.layout.item_question:
return QuestionsViewHolder.create(parent);
case R.layout.view_network_state:
return NetworkStateViewHolder.create(parent, retryCallback);
case R.layout.item_list_recommended:
return RecommendedViewHolder.Companion.create(parent);
default:
throw new IllegalArgumentException("unknown view type");
}
}
@Override
public void onBindViewHolder(@NonNull RecyclerView.ViewHolder holder, int position) {
switch (getItemViewType(position)) {
case R.layout.item_question:
((QuestionsViewHolder) holder).bindTo((QuestionResponse) getItem(position));
break;
case R.layout.view_network_state:
((NetworkStateViewHolder) holder).bindTo(networkState);
break;
case R.layout.item_list_recommended:
((RecommendedViewHolder) holder).bindTo((Recommended) getItem(position), recommendedAdapter);
break;
}
}
private boolean hasExtraRow() {
return networkState != null && networkState != NetworkState.LOADED;
}
@Override
public int getItemViewType(int position) {
if (hasExtraRow() && position == getItemCount() - 1) {
return R.layout.view_network_state;
} else if(position == 0){
return R.layout.item_list_recommended;
} else {
return R.layout.item_question;
}
}
@Override
public int getItemCount() {
return super.getItemCount() + (hasExtraRow() ? 1 : 0);
}
public void setNetworkState(NetworkState newNetworkState) {
NetworkState previousState = this.networkState;
boolean hadExtraRow = hasExtraRow();
this.networkState = newNetworkState;
boolean hasExtraRow = hasExtraRow();
if (hadExtraRow != hasExtraRow) {
if (hadExtraRow) {
notifyItemRemoved(super.getItemCount());
} else {
notifyItemInserted(super.getItemCount());
}
} else if (hasExtraRow && previousState != newNetworkState) {
notifyItemChanged(getItemCount() - 1);
}
}
@Override
public void submitList(PagedList<HomeItem> pagedList) {
super.submitList(pagedList);
}
@Override
public void onCurrentListChanged(@Nullable PagedList<HomeItem> currentList) {
super.onCurrentListChanged(currentList);
}
private static DiffUtil.ItemCallback<HomeItem> feedDiffUtil = new DiffUtil.ItemCallback<HomeItem>() {
@Override
public boolean areItemsTheSame(HomeItem oldItem, HomeItem newItem) {
return oldItem == newItem;
}
@Override
public boolean areContentsTheSame(HomeItem oldItem, HomeItem newItem) {
return Objects.equals(oldItem, newItem);
}
};
}
lucandr
on 5 Feb 2019
The scrolling problem is fixed with this:
public class HomeAdapterNew extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
private NetworkState networkState;
private RetryCallback retryCallback;
private RecommendedAdapter recommendedAdapter;
private AsyncPagedListDiffer<HomeItem> mDiffer;
@Inject
public HomeAdapterNew() {
final AdapterListUpdateCallback adapterCallback = new AdapterListUpdateCallback(this);
mDiffer = new AsyncPagedListDiffer<>(new ListUpdateCallback() {
@Override
public void onInserted(int i, int i1) {
adapterCallback.onInserted(i + 1, i1);
}
@Override
public void onRemoved(int i, int i1) {
adapterCallback.onRemoved(i + 1, i1);
}
@Override
public void onMoved(int i, int i1) {
adapterCallback.onMoved(i + 1, i1 + 1);
}
@Override
public void onChanged(int i, int i1, @Nullable Object o) {
adapterCallback.onChanged(i + 1, i1, o);
}
}, new AsyncDifferConfig.Builder<HomeItem>(new DiffUtil.ItemCallback<HomeItem>() {
@Override
public boolean areItemsTheSame(@NonNull HomeItem homeItem, @NonNull HomeItem t1) {
return false;
}
@Override
public boolean areContentsTheSame(@NonNull HomeItem homeItem, @NonNull HomeItem t1) {
return false;
}
}).build());
}
public void setRetryCallback(RetryCallback retryCallback) {
this.retryCallback = retryCallback;
}
public void submitList(PagedList<HomeItem> pagedList) {
mDiffer.submitList(pagedList);
}
public void setRecommendedAdapter(RecommendedAdapter recommendedAdapter) {
this.recommendedAdapter = recommendedAdapter;
}
public PagedList<HomeItem> getCurrentList() {
return mDiffer.getCurrentList();
}
@NonNull
@Override
public RecyclerView.ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
switch (viewType) {
case R.layout.item_question:
return QuestionsViewHolder.create(parent);
case R.layout.view_network_state:
return NetworkStateViewHolder.create(parent, retryCallback);
case R.layout.item_list_recommended:
return RecommendedViewHolder.Companion.create(parent);
default:
throw new IllegalArgumentException("unknown view type");
}
}
@Override
public void onBindViewHolder(@NonNull RecyclerView.ViewHolder holder, int position) {
switch (getItemViewType(position)) {
case R.layout.item_question:
((QuestionsViewHolder) holder).bindTo((QuestionResponse) mDiffer.getItem(position));
break;
case R.layout.view_network_state:
((NetworkStateViewHolder) holder).bindTo(networkState);
break;
case R.layout.item_list_recommended:
((RecommendedViewHolder) holder).bindTo((Recommended) mDiffer.getItem(position), recommendedAdapter);
break;
}
}
private boolean hasExtraRow() {
return networkState != null && networkState != NetworkState.LOADED;
}
@Override
public int getItemViewType(int position) {
if (hasExtraRow() && position == getItemCount() - 1) {
return R.layout.view_network_state;
} else if (position == 0) {
return R.layout.item_list_recommended;
} else {
return R.layout.item_question;
}
}
@Override
public int getItemCount() {
return mDiffer.getItemCount() + (hasExtraRow() ? 1 : 0);
}
public void setNetworkState(NetworkState newNetworkState) {
NetworkState previousState = this.networkState;
boolean hadExtraRow = hasExtraRow();
this.networkState = newNetworkState;
boolean hasExtraRow = hasExtraRow();
if (hadExtraRow != hasExtraRow) {
if (hadExtraRow) {
notifyItemRemoved(mDiffer.getItemCount());
} else {
notifyItemInserted(mDiffer.getItemCount());
}
} else if (hasExtraRow && previousState != newNetworkState) {
notifyItemChanged(getItemCount() - 1);
}
}
}
When I swipe to refresh I get this:
java.lang.IndexOutOfBoundsException: Inconsistency detected. Invalid view holder adapter positionViewHolder{b46fd14 position=0 id=-1, oldPos=0, pLpos:-1 scrap [attachedScrap] tmpDetached no parent} android.support.v7.widget.RecyclerView{40c5213 VFED.V... ......I. 0,0-1080,1665 #7f0a0157 app:id/list_main}, adapter:com.android.features.home.home.feed.adapter.HomeAdapterNew@7f2ec50, layout:android.support.v7.widget.LinearLayoutManager@c4f2e49, context:com.android.features.home.HomeActivity@2be65fc
at android.support.v7.widget.RecyclerView$Recycler.validateViewHolderForOffsetPosition(RecyclerView.java:5715)
at android.support.v7.widget.RecyclerView$Recycler.tryGetViewHolderForPositionByDeadline(RecyclerView.java:5898)
at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:5858)
at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:5854)
at android.support.v7.widget.LinearLayoutManager$LayoutState.next(LinearLayoutManager.java:2230)
at android.support.v7.widget.LinearLayoutManager.layoutChunk(LinearLayoutManager.java:1557)
at android.support.v7.widget.LinearLayoutManager.fill(LinearLayoutManager.java:1517)
at android.support.v7.widget.LinearLayoutManager.onLayoutChildren(LinearLayoutManager.java:612)
at android.support.v7.widget.RecyclerView.dispatchLayoutStep1(RecyclerView.java:3875)
at android.support.v7.widget.RecyclerView.dispatchLayout(RecyclerView.java:3639)
at android.support.v7.widget.RecyclerView.onLayout(RecyclerView.java:4194)
at android.view.View.layout(View.java:20836)
at android.view.ViewGroup.layout(ViewGroup.java:6401)
at android.support.v4.widget.SwipeRefreshLayout.onLayout(SwipeRefreshLayout.java:625)
at android.view.View.layout(View.java:20836)
at android.view.ViewGroup.layout(ViewGroup.java:6401)
at android.widget.RelativeLayout.onLayout(RelativeLayout.java:1080)
at android.view.View.layout(View.java:20836)
at android.view.ViewGroup.layout(ViewGroup.java:6401)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
at android.view.View.layout(View.java:20836)
at android.view.ViewGroup.layout(ViewGroup.java:6401)
at android.support.constraint.ConstraintLayout.onLayout(ConstraintLayout.java:1915)
at android.view.View.layout(View.java:20836)
at android.view.ViewGroup.layout(ViewGroup.java:6401)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
at android.view.View.layout(View.java:20836)
at android.view.ViewGroup.layout(ViewGroup.java:6401)
at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1791)
at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1635)
at android.widget.LinearLayout.onLayout(LinearLayout.java:1544)
at android.view.View.layout(View.java:20836)
at android.view.ViewGroup.layout(ViewGroup.java:6401)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
at android.view.View.layout(View.java:20836)
at android.view.ViewGroup.layout(ViewGroup.java:6401)
at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1791)
at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1635)
at android.widget.LinearLayout.onLayout(LinearLayout.java:1544)
at android.view.View.layout(View.java:20836)
at android.view.ViewGroup.layout(ViewGroup.java:6401)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
at com.android.internal.policy.DecorView.onLayout(DecorView.java:944)
at android.view.View.layout(View.java:20836)
at android.view.ViewGroup.layout(ViewGroup.java:6401)
at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:2948)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:2635)
If I comment this lines, it doesn't crash but it's not refreshing:
final AdapterListUpdateCallback adapterCallback = new AdapterListUpdateCallback(this);
mDiffer = new AsyncPagedListDiffer<>(new ListUpdateCallback() {
@Override
public void onInserted(int i, int i1) {
//adapterCallback.onInserted(i + 1, i1);
}
@Override
public void onRemoved(int i, int i1) {
//adapterCallback.onRemoved(i + 1, i1);
}
@Override
public void onMoved(int i, int i1) {
//adapterCallback.onMoved(i + 1, i1 + 1);
}
@Override
public void onChanged(int i, int i1, @Nullable Object o) {
//adapterCallback.onChanged(i + 1, i1, o);
}
}, new AsyncDifferConfig.Builder<HomeItem>(new DiffUtil.ItemCallback<HomeItem>() {
@Override
public boolean areItemsTheSame(@NonNull HomeItem homeItem, @NonNull HomeItem t1) {
return false;
}
@Override
public boolean areContentsTheSame(@NonNull HomeItem homeItem, @NonNull HomeItem t1) {
return false;
}
}).build());
How can I solve this?
lucandr
on 5 Feb 2019
@kamgurgul can u reopen this issue?
lucandr
on 5 Feb 2019
If your header isn't a part of "PagedList
Anyway I think it isn't the right place for this issue :)
kamgurgul
on 5 Feb 2019
@kamgurgul the header is part of the "PagedList", why do u think this is not the right place for the issue?
I am having the same scrolling problem. Thanks for the answer @kamgurgul
lucandr
on 5 Feb 2019
I created a new issue @kamgurgul : Issue 548
Thanks for all
lucandr
on 5 Feb 2019
I have tried implementing a simple header but now all my items except the header have disappeared. If anyone could take a look at what could be missing I would love to know: https://stackoverflow.com/questions/57853321/how-to-add-a-header-to-a-pagedlist-using-android-paging-library
Edit: Ok I actually figured it out, I was using super.getItemCount() in the getItemCount() function when I should have been using differ.itemCount
danielwilson1702
on 9 Sep 2019
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Most helpful comment
You're right about the insert notification - If you want items above the PagedListAdapter, switch to using AsyncPagedListDiffer, and pass a custom ItemCallback that offsets the positions by one: