Nested RecyclerView doesn't recycle

Question

I have a very complex UI that requires multiple nested lists of lists and so on.

Currently i have an outer RecyclerView and inside there is another RecyclerView that is actually an expandable recycler(is a refactored version of this component). It Is a three layer hierarchy.

My problem is that the nothing is getting recycled. I dont have them inside NestedScrollView. They get loaded in memory from the moment they get created and onBindViewHolder never fires again.. As a result the scrolling is very rough.

Any suggestion on how to tackle this issue? Thanks in advance

Outer recycler

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fillViewport="true"
    android:background="@color/color_background_expandable_list">
    <android.support.design.widget.AppBarLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar">
        <android.support.v7.widget.Toolbar
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            android:background="?attr/colorPrimary"
            app:layout_scrollFlags="scroll|enterAlways|snap"
            app:popupTheme="@style/ThemeOverlay.AppCompat.Light"
            app:contentInsetStart="0dp">
            <android.support.v7.widget.RecyclerView
                android:id="@+id/rcv_bet_sports"
                android:scrollbars="none"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:background="#3D464F" />
        </android.support.v7.widget.Toolbar>
    </android.support.design.widget.AppBarLayout>
    <android.support.v7.widget.RecyclerView
        android:id="@+id/rcv_live"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="10dp"
        android:layout_marginBottom="10dp"
        android:layout_marginRight="5dp"
        android:layout_marginLeft="5dp"
        android:descendantFocusability="blocksDescendants"
        app:layout_behavior="@string/appbar_scrolling_view_behavior" />
</android.support.design.widget.CoordinatorLayout>

Inner Expandable recycler

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">
    <android.support.v7.widget.RecyclerView
        android:id="@+id/rcv_live"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />
</FrameLayout>

UPDATE This is the main Outer Adapter. I override GetItemViewId. Does that affect the recycling mechanism?

class LivePageAdapter : RecyclerView.Adapter
    {
        LiveContentPresenter _ContentPresenter;
        RecyclerView.RecycledViewPool _SharedPool = new RecyclerView.RecycledViewPool();

        public LivePageAdapter(LiveContentPresenter contentPresenter)
        {
            _ContentPresenter = contentPresenter;
        }

        public void AddWidget(PageWidgetModel widgetModel)
        {
            _ContentPresenter.Add(widgetModel);
        }

        public override int ItemCount => _ContentPresenter.WidgetCount;

        public override void OnBindViewHolder(RecyclerView.ViewHolder holder, int position)
        {
            _ContentPresenter.BindWidgetOnRow((LiveListViewHolder)holder, position);
        }

        public override RecyclerView.ViewHolder OnCreateViewHolder(ViewGroup parent, int viewType)
        {
            var type = (WidgetType)viewType;
            switch (type)
            {
                case WidgetType.Carousel:
                    return null;
                case WidgetType.HotRightNow:
                    return null;
                case WidgetType.ExpandableRecycler:
                    View liveListItem = LayoutInflater.From(parent.Context).Inflate(Resource.Layout.widget_row_live_list, parent, false);
                    return new LiveListViewHolder(liveListItem, _SharedPool);
                default:
                    return null;
            }
        }

        public override long GetItemId(int position)
        {
            return _ContentPresenter.WidgetModels[position].GetHashCode();
        }

        public override void OnViewRecycled(Java.Lang.Object holder)
        {
            base.OnViewRecycled(holder);
        }

        public override int GetItemViewType(int position)
        {
            return _ContentPresenter.GetWidgetType(position);
        }
    }

Have you tried overriding `onViewRecycled()` in your adapter for debugging? — Gotiasits, May 04 '18 at 12:59
Can you please check this answer here? https://stackoverflow.com/a/39060431/3145960 — Reaz Murshed, May 04 '18 at 14:18

score 0 · Answer 1 · answered May 04 '18 at 12:29

0

It happens when the children have the wrong height.

Just set layout_height to wrap_content of child item to fix it.

answered May 04 '18 at 12:29

Sergey Govyazin

76
4

i changed the item height(including the recyclerview's height since this is also an child) to wrap_content but still not recycling – Stamatis Stiliats May 04 '18 at 12:39

Nested RecyclerView doesn't recycle

1 Answers1