Android RecyclerView doesn't recycle items

Question

I have A recyclerView that have multiple recyclerView with a dynamic inflation, the response I

am getting from the server is a list that contains objects each one contains a list and attributes for the

recyclerView type (Vertical or Horizontal) LinearLayout.

everything works fine except that when the orienatation is Vertical the adapter wait to load all Views at once (stop recycling).

I have searched a lot to find a solution but nothing.

the Main `RecyclerView` inside `HomeFragment`

<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.gt.gcook.ui.home.HomeFragment">

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recyclerView"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:orientation="vertical"
        android:nestedScrollingEnabled="false"
        app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        tools:listitem="@layout/home_single_item" />
</androidx.constraintlayout.widget.ConstraintLayout>

home_single_item layout (contains of 2 `TextView` and `RecyclerView`)

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

    <TextView
        android:id="@+id/seeAllTV"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="32dp"
        android:layout_marginEnd="24dp"
        android:text="See all"
        android:textColor="@color/color_yellow"
        android:textSize="16sp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <TextView
        android:id="@+id/titleTV"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="24dp"
        android:layout_marginTop="32dp"
        android:text="Catigories"
        android:textColor="#707070"
        android:textSize="22sp"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recyclerView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="24dp"
        android:nestedScrollingEnabled="false"
        app:reverseLayout="false"
        android:clipToPadding="false"
        app:layoutManager="androidx.recyclerview.widget.GridLayoutManager"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/titleTV" />

</androidx.constraintlayout.widget.ConstraintLayout>

`onBindViewHolder` of Home `RecyclerView` .

override fun onBindViewHolder(holder: ViewHolder, position: Int) {
    when (position) {
        0 -> {
            holder.itemView.titleTV.text = "Categories"
            val mLayoutManager = LinearLayoutManager(holder.itemView.context)
            mLayoutManager.orientation = RecyclerView.HORIZONTAL
            holder.itemView.recyclerView.layoutManager = mLayoutManager
            holder.itemView.recyclerView.adapter = HomeCategoryAdapter()


        }
        1 -> { //here is the problem when Orintation is vertical.
            holder.itemView.titleTV.text = "Most rated recipes"
            val mLayoutManager = GridLayoutManager(holder.itemView.context, 2)
            mLayoutManager.orientation = RecyclerView.VERTICAL
            holder.itemView.recyclerView.layoutManager = mLayoutManager
            holder.itemView.recyclerView.adapter = MostRatedRecipeAdapter(clickListener)


        }
        else -> {
            holder.itemView.titleTV.text = "Favourite"
            val mLayoutManager = LinearLayoutManager(holder.itemView.context)
            mLayoutManager.orientation = RecyclerView.HORIZONTAL
            holder.itemView.recyclerView.layoutManager = mLayoutManager
            holder.itemView.recyclerView.adapter = HomeCategoryAdapter()
        }
    }
}

This is a complicated issue, but the long story short is that RecyclerViews inside other scrolling containers (like a RecyclerView...) causes the whole thing to stop recycling. I have observed this when you put a recyclerView inside a NestedScrollView or similar. It likely has to do with the "wrap_content" attributes causing the RV to inflate all views to determine what the space needed/available is, or perhaps the container unable to correctly size itself unless the RV reports "the total" space it needs... quite lame if you ask me :/ — Martin Marconcini, Jul 28 '20 at 10:11
Lame? it is exactly what `wrap_content` means **and adding `wrap_content` to RV doesn't make sens as you can only scroll something bigger in smaller container** wrap_content makes container and content even... also recycling works when inner RV has defined height ... — Selvin, Jul 28 '20 at 10:20
@Selvin so do you have a solution or work around for that issue? — Mohamed AbdelraZek, Aug 09 '20 at 09:05
There is no solution. You cannot get view recycling on a recyclerview which is nested in another recyclerview. There are mutlipe SO posts verifying this. Either you live with it, or restructure your code to provide one flat list of items to one recyclerview. — Carson Holzheimer, Aug 11 '20 at 00:37
@MohamedAbdelraZek you can use pagination in the second Recyclerview it may help to solve the issue a bit. — Mohit Dholakia, Aug 14 '20 at 14:13
I added "answer" below, since it wouldn't fit in a comment. Sorry for late response :) — Rinat Diushenov, Aug 15 '20 at 09:23
In rep history it's shown that you unaccepted the answer (or tried). I wonder if there is something wrong with the answer or was it just a missclick? — Rinat Diushenov, Sep 02 '20 at 05:11

Rinat Diushenov · Accepted Answer · 2020-08-15T10:13:49.943

Since your inner RV's height is set to wrap_content there is no way to enable recycling for that case. When its horizontal, recycling is working because it's width is match_parent and screen width is fixed. Recycling works only when there is defined height!

However, as i said there is room for optimization:

Right now, you are creating adapter for inner RV inside parent RV's onBindViewHolder() method, thus forcing inner RV to inflate ViewHolders every time parent RV decides to reuse it's previous ViewHolders via rebinding new values.

You can create adapters for inner RV inside onCreateVoewHolder() of parent RV and submit new list to inner adapter ( subsequently calling notifyDatasetChanged() ) inside OnBindViewHolder().

The above approach should certainly improve performance, at least on subsequent scrolling: recycling will work on parent RV scroll, meaning inner RV will retain its ViewHolders and reuse them to some degree.

Unfortunately, i don't have time to post snippet precisely for your scenario but you can have a look at my another answer: Show values of same key in one TextView in Recyclerview

Android RecyclerView doesn't recycle items

the Main RecyclerView inside HomeFragment

home_single_item layout (contains of 2 TextView and RecyclerView)

onBindViewHolder of Home RecyclerView .

1 Answers1

the Main `RecyclerView` inside `HomeFragment`

home_single_item layout (contains of 2 `TextView` and `RecyclerView`)

`onBindViewHolder` of Home `RecyclerView` .