Develop Reference

Is NestedScrollView still useful from API 26 and above?

I am currently checking my app for any issues with the new Android 12 overscroll animation. And I came across plenty screens which contain a RecyclerView inside a NestedScrollView. Usually like this:
<androidx.core.widget.NestedScrollView 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"
android:fillViewport="true">
<androidx.constraintlayout.widget.ConstraintLayout
android:id="#+id/constraintLayout_root"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<TextView [...] />
<TextView [...] />
<TextView [...] />
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/recyclerView_attachment_classifications"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginTop="?marginM"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#id/textView_categorize_title"
tools:itemCount="4"
tools:listitem="#layout/list_item_adm_attachment_classification" />
</androidx.constraintlayout.widget.ConstraintLayout>
</androidx.core.widget.NestedScrollView>
This causes some problems with the new overscroll animation. Unfortunately, I cannot show you a recording of the animation problem, but let me describe it: When the screen is at the topmost position and the user is scrolling upwards, all views should stretch a little in relation to the drag event. But it does not do that. It only shows this stretch animation for a very short period of time AFTER the user released their thumb from the screen.
What I have found out so far:
Setting the RecyclerViews isScrollContainer to any value has no impact
Setting the RecyclerViews isNestedScrollingEnabled to any value has no impact
Setting the RecyclerViews overScrollMode to any value has no impact
The same goes for the NestedScrollView
Ironically, replacing the NestedScrollView with a standard ScrollView solves my issue.
I was unable to replicate the problem in a sample app, so it is relatively safe to say that this issue is somewhere in my apps config and architecture. But since using a ScrollView solves my issue, I wanted to know if a NestedScrollView still has any usefulness on API 26 and above or if NestedScrollView is just for backwards compatibility for apps which support older Android versions as well?

Turns out the issues were produced by NestedScrollView and fixed by Google in core-ktx:1.7.0. I had it on version 1.6.0.

Having RecyclerView inside a NestedScrollView calls onBindView for all the items

I have two RecyclerViews placed vertically in a LinearLayout. I need to make both of them scrollable and that is why I have put the LinearLayout inside NestedScrollView
This is the my layout file.
<android.support.v4.widget.NestedScrollView xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fillViewport="true"
android:scrollbars="none">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<android.support.v7.widget.RecyclerView
android:id="#+id/featured_list"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
<android.support.v7.widget.RecyclerView
android:id="#+id/all_topic_list"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
</LinearLayout>
Also, I am disabling nested scrolling in Java code.
disableNestedScrolling(findViewById(R.id.all_topic_list));
disableNestedScrolling(findViewById(R.id.featured_list));
My RecylerView library version is 26.1.0
This works fine perfectly, but then onBindViewHolder method is getting called for all the items in the list. Ideally it should only be called for the visible items in the list.
I think the issue is happening because I am giving wrap_content to the RecyclerView. A lot of answers on this question suggest that the issue is solved in v23.2.1, but I am already using v26.1.0. How to solve this issue?

I had exactly the same problem. RecyclerViews are not meant to be placed inside scroll containers with the same scroll direction. The view recycling only works when the height is set to MATCH_PARENT.
Depending on the complexity of the content inside of the NestedScrollView and the anticipated amount of RecyclerView items:
Ignore the problem. If there are only a few simple items, you may
not need view recycling at all.
When I hit the problem, I analysed the layouts of other popular apps: For example, WhatsApp only uses RecyclerViews (or ListViews with view recycling) in some parts of their app.
Particularly, this group settings screen with hundreds of possible items is made of multiple ListViews wrapped by a ScrollView, without any view recycling.
Replace the NestedScrollView with a single
ReyclerView with multiple item types and put all of your scrollable content inside of it. This is the way to go if you need view recycling.
Beware that you also have to convert all the other content in the NestedScrollView (headers and footers, spacing) to RecyclerView items with their own ViewHolders.
If the setup is rather simple, I would recommend you to implement it without additional libraries, following the link above.
There are a few different libraries available to solve your problem (all of them follow the second approach with a single RecyclerView), but most come with a lot of extra features which you may not need:
RendererRecyclerViewAdapter
It comes with a ViewRenderer/ViewModel interface, which works like a
"partial" RecyclerView for a single item type. You would create one
for every item type and then register them in a single adapter.
Epoxy
A library/framework create by airbnb and used heavily in their app.
They have a lot of scrollable content (similar to a web page) with a
lot of different item types. Epoxy also helps with the composition of
the different items on a page, and it handles animations when the
content or its order changes. Too much if you only need it for a single screen.
Litho
A complete UI framework created by Facebook which comes with it's own rendering engine, a replacement for xml layouts and much more. As far as I understand, it allows you to do to handle large amounts of items (like the Facebook timeline) and the view recycling is handled automatically. Like Epoxy, you would only use this if your app includes things like endless scrolling with a lot of different item types and you really need the performance.
I tried Epoxy and RendererRecyclerViewAdapter, but after all I created my own multiple item type adapter. It can be created in less than 100 lines of code.

Starting from RecyclerView:1.2.0-alpha04 we can use ConcatAdapter to solve this problem
https://developer.android.com/reference/androidx/recyclerview/widget/ConcatAdapter

I tried your problem by adding 20 items in each recyclerview, with NestedScrollView application called onBindViewHolder method 40 times. As you disabling nested scrolling in Java code i suggest to use Scrollview. By using ScrollView application called onBindViewHolder 33 times.
If you fix your recyclerView's height to specific size instead of "match-parent" it will reduce call to onBindViewHolder greatly.
<ScrollView 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"
android:fillViewport="false">
<android.support.v7.widget.LinearLayoutCompat
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context="com.example.vishal.my2.MainActivity">
<android.support.v7.widget.RecyclerView
android:id="#+id/featured_list"
android:layout_width="match_parent"
android:layout_height="300dp" />
<android.support.v7.widget.RecyclerView
android:id="#+id/all_topic_list"
android:layout_width="match_parent"
android:layout_height="300dp" />
</android.support.v7.widget.LinearLayoutCompat>
</ScrollView>
If Specifying hardcoded value to recyclerView's height does not meet your application requirement then you can try using ListView instead of recyclerView. pardon me if i am wrong, This was my first time answering any question.

Add this to nested scroll view android:fillViewport="false"

Two RecyclerViews on one screen

I have been given the task to implement a feature on Mobile application. Previously I had no experience with Android nor Java.
What I need is one screen (one fragment) to display two lists of events with uneven number of members one after another, let's call them ListX and ListY.
I've made layout containing two RecyclerViews and two labels (one label to act as header for each of recycler views).
It is working as it is now and I have events displayed, but ListX is scrollable even though its layout_height is set to wrap_content (only 6 items displayed at the time) while ListY is not scrollable and is displaying all events in collection.
What I need is all items from ListX displayed in first RecyclerView (without scroll), and after that ListY displayed in second RecyclerView without scroll too.
Layout:
<FrameLayout
android:id="#+id/resultsView"
android:layout_width="match_parent"
android:layout_height="match_parent">
<android.support.v4.widget.SwipeRefreshLayout
android:id="#+id/swipeContainer"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:visibility="visible">
<ScrollView
android:layout_width="match_parent"
android:layout_height="match_parent">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical" >
<TextView
android:id="#+id/label_daily" />
<android.support.v7.widget.RecyclerView
android:id="#+id/list_daily"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginEnd="8dp"
android:layout_marginStart="8dp"
android:layout_marginTop="8dp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/label_daily"
tools:listitem="#layout/fragment_timetracking_event_item" />
<TextView
android:id="#+id/label_unfinished" />
<android.support.v7.widget.RecyclerView
android:id="#+id/list_unfinished"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginEnd="8dp"
android:layout_marginStart="8dp"
android:layout_marginTop="8dp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/label_unfinished"
tools:listitem="#layout/fragment_timetracking_event_item" />
</LinearLayout>
</ScrollView>
</android.support.v4.widget.SwipeRefreshLayout>
</FrameLayout>
As you can see from XML both RecyclerViews have layout_height set to wrap_content yet first RecyclerView is not obeying.
Here is sketch of how it should look like
Is there any way to put both lists in one RecyclerView and make custom separators? Or any other way to anchor beginning of one list to the end of the other and make them show all items without scroll?
I hope to get help here.

You don't need 2 recyclerViews, you can achieve using single recylcerView.
You should read about getItemViewType & using same in bindViewHolder & createViewHolder
You can specify these three types
Header
DailyItem
FinishItem
Create your list like this
add Daily HEADER
add Daily ITEMS
add Unfinished HEADER
add Unfinished ITEMS
Now you can render both lists in single recyclerview

Your problem
...other way to anchor beginning of one list to the end of the other and make them show all items without scroll?
has a simple solution without rewriting your code to the one RecycleView - just put android.support.v4.widget.NestedScrollView instead of ScrollView in your xml layout. It seems to be a bug in the ScrollView widget, which is fixed in android.support.v4.widget.NestedScrollView.
P.S. After solving this problem you will face with other problem - Android RecycleView scrolls with no momentum, which is resolved in "RecyclerView within NestedScrollView Scrolling Issue". It is fine only for short item list in RecycleView because as it is mentioned in comments to above article
This is not a good solution since disabling nested scrolling will disable cell reuse as well, therefore loading all cells at once.
which will have impact on the memory consumption of your app in the case of long item list.

Layout Jerking when RecyclerView inside a ScrollView

Im creating RecyclerView and ListView inside ScrollView and im getting problems with the scroll.. The scroll is Jerking (unable to get smooth scroll), I know its the problem with the RecyclerView inside the ScrollView, because layout is scrolling without any problem when swiping until the ListView exists but once RecyclerView items enter the layout it starts to jerk( only scrolling with the finger, no proper scroll when finger is taken off). Here is the code in the xml
<ScrollView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fillViewport="true">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<ListView
android:id="#+id/lv_home_dropdown"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:divider="#color/colorWhite"
android:dividerHeight="0.5dp"
android:visibility="gone"/>
<android.support.v7.widget.RecyclerView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="#+id/recycleView"
android:background="#color/colorWhite">
</android.support.v7.widget.RecyclerView>
</LinearLayout>
</ScrollView>

Nested views that scroll along the same axis have always been
problematic on Android. Recently Google has added nested scrolling
support. In order to have this on older platform levels, you should
use the views in the support library like NestedScrollView and
RecyclerView.
ListView does not work with wrap_content as its height. You can do
this with RecyclerView if you have the latest version of the
RecyclerView support library. Besides, you are already using RecyclerView in one place, you might as well use them exclusively.
ListView is not really meant to be a "drop down". Perhaps you should consider a Spinner instead.

I have it finally.!!
Just add the following line of code in you class where you are calling the RecyclerView
mRecyclerView = (RecyclerView)tmpView.findViewById(R.id.recycleView);
mRecyclerView.setNestedScrollingEnabled(false);
It works for me!

Create a RecyclerView with both horizontal and vertical scrolling

Over the past few weeks I've been learning to use the RecyclerView. I need to implement a horizontal list, ie, that by turning the device in landscape mode like so:
I found the best solution for this (how to create the horizontal displacement of RecyclerView, here), but encountered another problem. The item RecyclerView was larger than the height of the device (in landscape, horizontal), so I need to create a vertical and horizontal displacement, simultaneously.
I looked at the Android Developer methods for the LayoutManager class, but my skills are not high enough to understand most of the methods. I also tried putting a RecyclerView vertically inside another RecyclerView horizontally with all the content, but I get error:
IllegalStateException: RecyclerView has no LayoutManager
To rememedy this I removed all <View ... /> elements from the XML file, but this does not give any results.
To clarify what I am asking: is it possible to have my layout scroll both horizontally and vertically, and if you could explain how I would appreciate it.

I was so angry about all the problems that had tended with the application that had not thought about the easiest solution.
In a RecyclerView consists of two XML files, the main one where the RecyclerView is declared and another with content.
The simplest solution was to introduce the RecyclerView within a ScrollView. So I can move all items at a time thanks to ScrollView vertically and horizontally I can move the items thanks to RecyclerView in landscape mode.
activity_main.xml
<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_margin="#dimen/cardIn_margin_ext">
<android.support.v7.widget.RecyclerView
android:id="#+id/recycler_view"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:scrollbarStyle="outsideInset"
android:scrollbars="horizontal" />
</ScrollView>

The accepted answer did'nt work for me. I had to use the HorizontalScrollView instead of simple ScrollView.
<HorizontalScrollView xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_margin="#dimen/cardIn_margin_ext">
<android.support.v7.widget.RecyclerView
android:id="#+id/recycler_view"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:scrollbarStyle="outsideInset"
android:scrollbars="horizontal" />
</HorizontalScrollView >