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Loading items into a RecyclerView with stackFromEnd = true doesn't scroll to bottom

I have a chat app and i'm trying to ensure that when the user opens the screen the items display from the bottom with the most recent right above the input area. I've used a custom view for the input area and both the recycler and the custom view are within a ConstraintLayout.
My problem is that when I load items into the list, if the number of items is greater than the size of the recycler, it will not fully show the last item. When I make the input area visibility = Gone then the items display properly at the bottom. It's almost like the recyclers LinearLayoutManager thinks that the height of the Recycler is of the screen without the input field. I've manually printed out the size of the views and used layout inspector to ensure that the recycler is indeed drawn in the correct location (above the input and below the navigation bar).
What could be causing such an issue? I should note that whenever you click on a Linkified text in a chat bubble that the list scrolls a small amount equal to the offset that's incorrect when you open the screen. Clearly something is not measuring right here and not sure where to begin.
I should also note that if I try to add a post with smoothScroll it will go to the end of the list but then whenever a new item appears in the list from sending a message the items above the most recently added one seem to jump up a little with an unnecessary animation. It's like the last item in the list is in some special state?
if you're curious this is my scrolling function:
private fun scrollToFirstItem(dueToKeyboard: Boolean = false) {
val stackingFromEnd = (recyclerView.layoutManager as LinearLayoutManager).stackFromEnd
if (stackingFromEnd) {
val firstPosition = recyclerView.adapter?.itemCount?: 0 - 1
if (dueToKeyboard ) {
recyclerView.scrollBy(0, Integer.MAX_VALUE)
} else {
recyclerView.scrollToPosition(firstPosition)
}
recyclerView.post { recyclerView.smoothScrollToPosition(firstPosition) }
} else {
recyclerView.scrollToPosition(0)
}
}
And my xml for my fragment:
<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">
<include
android:id="#+id/searchView"
layout="#layout/compose_new_message_include"/>
<com.airbnb.epoxy.EpoxyRecyclerView
android:id="#+id/conversationEpoxyRV"
android:layout_width="match_parent"
android:layout_height="0dp"
android:scrollbars="vertical"
app:layout_constraintTop_toBottomOf="#id/searchView"
app:layout_constraintBottom_toTopOf="#id/composeView"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
tools:listitem="#layout/conversation_item_inbound"/>
<include layout="#layout/conversation_pip_view"
android:id="#+id/selectedMediaContainer"/>
<****.ComposeView
android:id="#+id/composeView"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintBottom_toBottomOf="parent"/>
</androidx.constraintlayout.widget.ConstraintLayout>
Any help is appreciated, I'm so lost..

To me this feels like more of an issue in the layout rather than in the scrolling function. I hope that this can be resolved easily if you use a Relative Layout instead of a Linear Layout. So in case if it may be helpful, i'll add my solution below using a Relative Layout.
<RelativeLayout
android:id="#+id/layout"
android:layout_width="match_parent"
android:layout_height="match_parent">
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/recycle_view"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_above="#id/input_field">
</androidx.recyclerview.widget.RecyclerView>
<EditText
android:id="#+id/input_field"
android:layout_width="match_parent"
android:layout_height="50dp"
android:layout_alignParentBottom="true"/>
</RelativeLayout>
So in case if it is not clear what i have done, an EditText element is set to align to the bottom of parent which is a Relative Layout. Then a RecyclerView is added so that RecylerView will be always constraint above the EditText but not overlapped.

Everything looks fine, except the restrictions you added to recycleview design, I see that you are setting the recycleview to top of searchView app:layout_constraintTop_toBottomOf="#id/searchView" while the searchView view is not restricted as should it be.
It's better when using ConstraintLayout to restrict every view inorder avoid unexpected behaviors, because every view has a relation with other view will be effected with other view (x, y), therefore your searchView should be look like:
<include
android:id="#+id/searchView"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
layout="#layout/compose_new_message_include"/>

Give the size of arraylist of your data to smoothScrollToPosition
var linearLayoutManager = LinearLayoutManager(context)
recyclerView.layoutManager=linearLayoutManager
recyclerView.adapter=adapter
linearLayoutManager.setStackFromEnd(true)
adapter.notifyDataSetChanged()
recyclerView.smoothScrollToPosition(dataMsgs.size())

I had a similar problem some years back and I solved it with scrollToPositionWithOffset (support library). Of course this was before constraint was used....
I kept my newer items at the bottom, too. The code I used for scrolling after inserting an item was:
((LinearLayoutManager) layoutManager).scrollToPositionWithOffset(getItemCount() - 1, 0);
To scroll and adjust the awkward positioning after removing an item, I used:
View vTopCard = layoutManager.getChildAt(0);
// Get its adapter position
final int topCardPos = layoutManager.getPosition(vTopCard);
// Get top of card position
int topOffset = layoutManager.getDecoratedTop(vTopCard);
int cardMargin = (int) getResources().getDimension(R.dimen.card_vertical_margin);
((LinearLayoutManager) layoutManager).scrollToPositionWithOffset(topCardPos, topOffset - cardMargin);
The getDecoratedTop helps with the "bounce" and final positioning, as does factoring the vertical margin.
I hope this helps (at least part of your issue)! Like I said, this is old code (when I was learning to program Android and Java at the same time), so if I left something out, let me know and I'll reexamine the app's code in more detail (though, I'll have to find the time).
Good luck!

RecyclerView not updating the view properly with ConstraintLayout Group Visibility

Problem:
It seems when I have a specific combination of views and setVisibility between Visible and Gone the RecyclerView does not update properly after initial load. I have a RelativeLayout->ConstraintLayout->Constraint Group(with visibility dynamically set). The view within the constraint group is not updating properly.
Example Use Case of Problem:
So the linked code below it will show a search view at the top. The initial state of empty shows the view properly(With the search icon showing). Then if you type "T" then the search icon will disappear(it shouldn't). So if you either delete the T or type the next letter "E" then it shows again. Also if you delete all search text and type T again it will show.
View Code:
<layout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:bind="http://schemas.android.com/apk/res-auto">
<data>
<variable
name="vm"
type="com.example.davidcorrado.myapplication.PlayerVM" />
</data>
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<android.support.constraint.ConstraintLayout
android:id="#+id/playerCell_main_layout"
android:layout_width="match_parent"
android:layout_height="84dp"
android:layout_alignParentTop="true">
<android.support.constraint.Group
android:id="#+id/playerCell_status_group"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:visibility="#{vm.showingStatusIcons}"
app:constraint_referenced_ids="playerCell_lineup_status_image" />
<ImageView
android:id="#+id/playerCell_lineup_status_image"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
android:src="#drawable/ic_search" />
</android.support.constraint.ConstraintLayout>
</RelativeLayout>
</layout>
Quirks that might help:
1) If I move the visibility line to the relativeLayout or the ConstraintLayout the things seem to work
2) If I remove the RelativeLayout view things seem to work.
See the below for the full code example:
https://github.com/DavidCorrado/LayoutIssue

As far as I can tell, the reason the search icon disappears is due to the call to ObservableList.clear() then ObservableList.addAll(*)
So the disappear happens on the clear, then the reappear happens on the addAll.
As the callbacks in the adapter kick in on both calls, my hunch is it animates the view to disappear, then animates to show when the addAll is triggered.
I have verified this by not actioning a 'List.clear()' and instead in your textChange listener simply adding more views to the list.
I'm not sure how you would clear and add items to the list without animating the clear, perhaps there are some settings you can toggle in the RecyclerAdapter to ignore the remove of Views or not animate the entry of Views?
My adjusted code in your callback for class PlayersListVM
class PlayersListVM {
val filteredVms: ObservableList<ViewModel> = ObservableArrayList<ViewModel>()
val showing = PlayerVM(isShowing = true)
val missing = PlayerVM()
init {
filteredVms.add(showing)
}
fun onQueryChanged(newText: String) {
if (filteredVms.size % 2 == 1) filteredVms.add(missing)
else filteredVms.add(showing)
}
}

Exclude certain elements from being animated in android layout transitions

I have a question regarding the android layout transition framework. In particular i want to achieve an effect that a certain part of an layout slides down or up depending on the visibility of another view(s).
Imagine the following layout. (And please overlook the nested LinearLayouts here ;) )
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:animateLayoutChanges="true">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<View
android:id="#+id/changingView1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:visibility="gone"/>
<View
android:id="#+id/changingView2"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:visibility="gone"/>
</LinearLayout>
<LinearLayout
android:id="#+id/movingView"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:animateLayoutChanges="false"/>
</LinearLayout>
Now what i want to achieve is that when changingView1 and changingView2 change their visibility that movingView slides up or down.
By enabling the LayoutTransition.CHANGING for the parent layout the sliding part works fine so. But this has the side effect that the movingView will also be animated when there are being items added or removed because this layout changes its bounds. And here lies my problem because this results in a very strange looking animation.
So back to my question. Is there a way to keep the sliding animation without animating layout bound changes on the movingView?
Disabling layoutTransitions on the movingView obviously does not help because this only effects the animations of the child views. I also tried playing around with enabling and disabling different LayoutTransitions on the parent layout but so far without the desired effect.
If i can add more details please let me know otherwise i hope someone can help me out.
Thanks in advance!

I know it's late but hope it can help someone. Since android:animateLayoutChanges is the property of the direct parent, you can wrap your View/Layout in a FrameLayout (or some other ViewGroup) and set android:animateLayoutChanges="false" on the new parent.

To avoid unwanted animations you can remove the animate layout changes by code when needed, something like this:
//removing the animate layout changes to prevent the default animation for the newly added items
parentLayout.setLayoutTransition(null);
/* do some logic to add the new views */
//add the animate layout changes back so the over changes will be still animated
new Handler().post(() -> {parentLayout.setLayoutTransition(new LayoutTransition());});

ViewPager in CoordinatorLayout shrinks unexpectedly

In my Android app running on Android 5.1.1 I have a layout using a Toolbar with a TabLayout, and underneath is a ViewPager. All of these are put together in a CoordinatorLayout.
In the first page of the ViewPager is a RecyclerView serving CardView items.
My problem is that my ViewPager keeps getting resized in a way so that my CardView list items are cropped.
My main layout looks basically like this:
<android.support.design.widget.CoordinatorLayout
android:layout_width="match_parent"
android:layout_height="match_parent" >
<android.support.design.widget.AppBarLayout
android:layout_height="wrap_content"
android:layout_width="match_parent" >
<android.support.v7.widget.Toolbar
android:layout_width="match_parent"
android:layout_height="wrap_content" />
<android.support.design.widget.TabLayout
android:layout_width="match_parent"
android:layout_height="wrap_content" />
</android.support.design.widget.AppBarLayout>
<android.support.v4.view.ViewPager
app:layout_behavior="#string/appbar_scrolling_view_behavior"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
</android.support.design.widget.CoordinatorLayout>
And the first fragment served by my ViewPager looks like:
<FrameLayout
android:layout_width="match_parent"
android:layout_height="match_parent" >
<android.support.v7.widget.RecyclerView
android:scrollbars="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_margin="8dp"/>
</FrameLayout>
This renders something that looks like this:
When clicking a button in my layout, I use startActivityForResult to invoke another activity, and when returning to my activity sometimes suddenly my list is cropped so that only half of the first item is visible:
After swiping horizontally to another pager in the ViewPager and then back, the problem disappears, so it does seem a re-layout has not been properly triggered. Pressing HOME and then resuming my activity does NOT resolve the problem though. Note that this happens even if I am not modifying my layout in any way, I am simply returning from a startActivityForResult call. And yes, it only happens sometimes... And I have no background threads running that could explain the apparent random behavior.
At first I thought it was the RecyclerView that had shrunk, but using HierarchyViewer I was able to find that it was actually the entire ViewPager that had shrunk to about half its original height.
I tried various hacks to get around this, including calling invalidate() and requestLayout() on my entire view hiearchy, but nothing seemed to help (although swiping to another page and back again fixes it). Also, those are not the kind of solutions I want to resort to... Then I tried changing my ViewPager height to wrap_content, which did in fact solve this particular problem; after returning to my activity the first item in my RecyclerView is never cropped, and I can scroll down to the other items. However, now instead the very last item of my list is always cropped, as can be seen in this screenshot where the list is scrolled all the way to the bottom:
Since I am now at a point where I don't really understand what's going on, I need some help. What should I really use as the layout_height for my ViewPager, and - above all - why? To me, match_parent makes sense, but how should I be thinking here? Is there a rational reason my views got cropped when using match_parent, or did I in fact encounter a bug in ViewPager, RecyclerView and/or CoordinatorLayout? How do I make sure that my ViewPager consistently fills the entire screen area below the AppBar, and that my RecyclerView can be scrolled vertically to properly render all CardView list items?

It turns out this is almost certainly a bug in CoordinatorLayout or even more likely in AppBarLayout$ScrollingViewBehavior. In an effort to create a MCVE I realized it was the fact that my sub-activity had an IME on screen that caused the shrinking of the ViewPager - when my activity is resumed after onActivityResult, the ViewPager is shrunk as a result of reduced screen real-estate from the IME, but is never expanded again despite the fact that the IME is no longer being shown and the fact that the CoordinatorLayout is indeed expanded.
After debugging and stepping through onLayout and onMeasure of CoordinatorLayout and ViewPager I am now fairly sure that the CoordinatorLayout does not properly propagate the change in size to its children.
I found that I can "fix" the problem by calling requestLayout on my ViewPager, but only if the call is sufficiently delayed (10 ms never works, 100 ms works most of the time):
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
mHandler.postDelayed(new Runnable() {
#Override
public void run() {
mViewPager.requestLayout();
}
}, 100);
}
This obviously isn't a robust solution, but after investigating some more it turns out I probably don't even need CoordinatorLayout since I don't really have any advanced scrolling behavior. So my solution will be to simply go with a LinearLayout or RelativeLayout as my root view group instead. Nice and simple, no need to complicate things.
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<android.support.design.widget.AppBarLayout
android:layout_height="wrap_content"
android:layout_width="match_parent" >
<android.support.v7.widget.Toolbar
android:layout_width="match_parent"
android:layout_height="wrap_content" />
<android.support.design.widget.TabLayout
android:layout_width="match_parent"
android:layout_height="wrap_content" />
</android.support.design.widget.AppBarLayout>
<android.support.v4.view.ViewPager
android:layout_width="match_parent"
android:layout_height="match_parent"/>
</LinearLayout>
I will however try to condense this into a simple example and file a bug with Google.
As to what I should use as the height for my ViewPager, my original use of match_parent still seems reasonable. The fact that wrap_content solved the problem (but caused other problems) is probably just due to inconsistencies caused by the bug.

I've experienced a similar issue when using an older version of the support library.
See these related issues:
https://code.google.com/p/android/issues/detail?id=176406
https://code.google.com/p/android/issues/detail?id=176187
Make sure you're using the latest Support library, version 23.1 as of this writing.

In your fragment just remove the frameLayout and make recyclerView parent...I hope it will work:
<android.support.v7.widget.RecyclerView
android:scrollbars="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_margin="8dp">
<android.support.v7.widget.RecyclerView/>

NestedScrollView (NSV) in CoordinatorLayout (CL): NSV Not at Top When Loaded

I am using an NSV in a CL for the ability to have the toolbar compress when the NSV scrolls down. The problem that I am having is that my NSV is not scrolled to the top when it loads, instead, it is offset from the top of the NSV by quite a margin (I am not certain where this spacing is coming from, it's not in the layout).
Please take a look at the screen captures, the first one shows how the NSV loads and you can clearly see the NSV has scrolled down quite a bit from the top by comparing the second (when I scroll the NSV to the top manually):
I did some updates to this layout and it caused this to occur, previously, it loaded at the top without issue. However, I did not add any spacing that should have caused this.
Here is the layout I'm using for this:
<android.support.design.widget.CoordinatorLayout
android:id="#+id/cl_goal_detail"
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="0dp"
android:layout_weight="1">
<android.support.design.widget.AppBarLayout
android:id="#+id/abl_goal_detail"
android:layout_width="match_parent"
android:layout_height="144dp"
app:theme="#style/ThemeOverlay.AppCompat.Dark.ActionBar">
<android.support.design.widget.CollapsingToolbarLayout
android:id="#+id/collapsing_toolbar_goal_detail"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="#dimen/content_space_double"
app:collapsedTitleTextAppearance="#style/title.dark"
app:expandedTitleTextAppearance="#style/display3.plus.dark"
app:layout_scrollFlags="scroll|exitUntilCollapsed">
<android.support.v7.widget.Toolbar
android:id="#+id/toolbar_goal_detail"
style="#style/toolbar"
app:layout_collapseMode="pin"
app:popupTheme="#style/ThemeOverlay.AppCompat.Light"/>
</android.support.design.widget.CollapsingToolbarLayout>
</android.support.design.widget.AppBarLayout>
<android.support.v4.widget.NestedScrollView
android:id="#+id/nsv_goal_detail"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="#dimen/content_space_half"
android:paddingLeft="#dimen/content_space_half"
android:paddingRight="#dimen/content_space_half"
app:layout_behavior="#string/appbar_scrolling_view_behavior">
<FrameLayout
android:id="#+id/container_goal_detail"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_gravity="fill_vertical"/>
</android.support.v4.widget.NestedScrollView>
</android.support.design.widget.CoordinatorLayout>
Any ideas would be appreciated!

OK! After a solid DAY of debugging every single component of my layout and Fragment I identified what I believe is a bug.
First, the issue: Turns out that having elements in your NSV's child view that change visibility to View.GONE upon runtime are causing the list to scroll down. I noticed that the list scrolls to just above the element where the visibility was toggled (including any margins set on the view).
Second, the fix: I fixed this issue by setting all the views to have android:visibility="gone" in the xml layout, then, I toggle each view's visibility as needed. Previously, the views were visible by default and then I worked from there. I just needed to change my logic to start with them all GONE, not terribly difficult.
I assume this works because the views you are going to hide at runtime do not form a part of the overall height calculation when the NSV is created in onCreateView(). Once the fragment progresses past onCreateView() it's safe to dynamically change the views, however, if the views are calculated as part as the height in onCreateView() and THEN hidden with View.GONE, measurements go wonky and you end up with a list scrolled down significantly.

Have you tried adding below line in your viewgroup i.e. FrameLayout in your case
android:descendantFocusability="blocksDescendants"
I think this will also work for you.
If not try it adding in NSV.

In my case, there was an EditText near the bottom of my scrolling content that was grabbing focus. Since NestedScrollView does some weird layout stuff, the focused view didn't scroll to the top when the activity started, so the real cause was not readily apparent. Adding this to the NestedScrollView's child layout fixed it for me:
android:focusableInTouchMode="true"

Your post answer helped me a lot to find out my issue (btw, it was the same). But I got it worked in a different way. I guess you are using a RecyclerView. In my case I'm using 3 RecyclerViews. Well, from your answer I started hiding the recyclers and I found out just one of them was causing this issue. What I did is I populated with a postDelayed:
new Handler().postDelayed(new Runnable() {
#Override
public void run() {
recyler.setLayoutManager(new LinearLayoutManager(getApplicationContext()));
recyler.setAdapter(new MyAdapter(myList));
}
}, 3000);
That worked fine!