No animation on item removal on RecyclerView

问题:

I am using RecyclerView for the first time. Everything is working fine except that there is no animation on item removal even though the animation on item addition works just fine.

I have not set any custom item animator, but according to the documentation:

Animations for adding and removing items are enabled by default in RecyclerView.

So the animations on removal should work.

I would like to have the default animation on removal, but can't get that to work.

This is how I setup the RecyclerView:

private void setupRecyclerView() {   mRecyclerView = (RecyclerView) mRootView.findViewById(R.id.recycler_view);   mRecyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));   View emptyView = mRootView.findViewById(R.id.empty_view);   mAdapter = new RoutineAdapter(getActivity(), mRoutineItems, emptyView);   mRecyclerView.setAdapter(mAdapter); } 

This is my adapter:

private class RoutineAdapter       extends RecyclerView.Adapter<RoutineAdapter.ViewHolder> {  private final Context mContext; private List<RoutineItem> mData; private View mEmptyView;      public RoutineAdapter(Context context, List<RoutineItem> data, View emptyView) {       mContext = context;       mData = data;       mEmptyView = emptyView;       setEmptyViewVisibility();     }      public void add(RoutineItem routineItem, int position) {       mData.add(position, routineItem);       setEmptyViewVisibility();       notifyItemInserted(position);     }      public void remove(int position){       mData.remove(position);       setEmptyViewVisibility();       notifyItemRemoved(position);     }      public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {       final View view = LayoutInflater.from(mContext).inflate(           R.layout.fragment_routines_list_item, parent, false);       return new ViewHolder(view);     }      @Override     public void onBindViewHolder(ViewHolder holder, final int position) {       final RoutineItem routineItem = getItem(position);       holder.circle.setBackgroundResource(           colorNumberToDrawableResource(routineItem.colorNumber));       holder.initial.setText(routineItem.routineName.substring(0, 1));       holder.routineName.setText(routineItem.routineName);       holder.lastTimeDone.setText(routineItem.lastTimeDoneText);       if (routineItem.isSelected) {         holder.itemView.setBackgroundColor(             getResources().getColor(R.color.background_item_selected));       } else {         holder.itemView.setBackgroundResource(             R.drawable.darker_background_on_pressed);       }       holder.itemView.setOnClickListener(new View.OnClickListener() {         @Override         public void onClick(View v) {           mPresenter.onRoutineClicked(routineItem.routineName);         }       });       holder.itemView.setOnLongClickListener(new View.OnLongClickListener() {         @Override         public boolean onLongClick(View v) {           mPresenter.onRoutineLongClicked(routineItem.routineName);           return true;         }       });     }      @Override     public int getItemCount() {       return mData.size();     }      public RoutineItem getItem(int position) {       return mData.get(position);     }      private void setEmptyViewVisibility() {       if (getItemCount() == 0) {         mEmptyView.setVisibility(View.VISIBLE);       } else {         mEmptyView.setVisibility(View.GONE);       }     }      class ViewHolder extends RecyclerView.ViewHolder {       public final View circle;       public final TextView initial;       public final TextView routineName;       public final TextView lastTimeDone;        public ViewHolder(View view) {         super(view);         circle = view.findViewById(R.id.circle);         initial = (TextView) view.findViewById(R.id.initial);         routineName = (TextView) view.findViewById(R.id.routine_name);         lastTimeDone = (TextView) view.findViewById(R.id.last_time_done);       }     } } 

Fragment_routines_list_item.xml:

<?xml version="1.0" encoding="utf-8"?> <RelativeLayout   xmlns:android="http://schemas.android.com/apk/res/android"   android:layout_width="match_parent"   android:layout_height="match_parent"   android:minHeight="@dimen/standard_list_item_height"   android:paddingBottom="8dp"   android:background="@drawable/darker_background_on_pressed"   android:clickable="true">     ...... </RelativeLayout> 

What am I doing wrong that causes the default removal animation to not work?

回答1:

The proper way to remove an item from recycler view is to remove the item from data set and then telling the adapter that the item is removed like so

myDataset.remove(position); // myDataset is List<MyObject> mAdapter.notifyItemRemoved(position); 

回答2:

Solved it.

The issue was that, after calling mAdapter.remove(position), another part of my code was calling mAdapter.notifyDataSetChanged() which I assume stops the removal animation.

To sum up, if you call mAdapter.notifyDataSetChanged while there is an animation ongoing the animation will stop.

回答3:

Use notifyItemRemoved(position) instead of notifyDataSetChanged() like below

myDataset.remove(position); notifyItemRemoved(position); 

because notifyDataSetChanged() simply notifies the updated data without any animations.

回答4:

Another reason for a not properly working remove animation could be the RecyclerViews height. Verify that the height is match_parent and NOT wrap_content!

回答5:

I was able to remove the view with the animation and updated indices as follows:

Within the adapter,

public boolean removeItem(int position) {     if (data.size() >= position + 1) {         data.remove(position);         return true;     }     return false; } 

While removing the views, call

if (adapter.removeItem(position)) {     adapter.notifyItemRemoved(position);     adapter.notifyItemRangeChanged(position, adapter.getItemCount()); } 

I have used a boolean method to ensure that double clicks,etc. don't cause a crash.

回答6:

after long debugging I realized I had to add setHasStableIds(true) to my adapter and implement

@Override public long getItemId(int position) {     return position; } 

after that remove animation began to work

回答7:

I ran into same issue, and I fixed this by implementing my own RecyclerView, and in my recyclerview, I did this:

public class MyRecyclerView extends RecyclerView {    private View mEmptyView;    private AdapterDataObserver mDataObserver = new AdapterDataObserver() {        public void onChanged() {           super.onChanged();           updateEmptyView();        }         public void onItemRangeRemoved(int positionStart, int itemCount) {            super.onItemRangeRemoved(positionStart, itemCount);            updateEmptyView();        }         public void onItemRangeInserted(int positionStart, int itemCount) {           super.onItemRangeInserted(positionStart, itemCount);           updateEmptyView();        }      };      // private void setAdapter() {}      private void updateEmptyView() {          // update empty view's visibility     }  } 

Basically, when you add/remove item into/from recyclerview, you can call notifyItemInserted()/ notifyItemRemoved() and notifyItemRangeChanged(), these method will invoke onItemRangeRemoved() / onItemRangeInserted() in mDataObserver. So in these method, you can update empty view's visibility, and it will not break animations.

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