Develop Reference

How to keep data in recycler view when screen orientation from portrait to landscape?

I have a custom object array to show in recycler view and I'm using GridLayout manager for my recylerview and showing (2x4),(3x3) etc. squares.
When user click these squares it's color changed.
But when screen orientate, view is refreshing.
My question is how to keep this data (selected square's color ) when screen orientation ?

Create an interface:
public interface ClickCallback {
void onItemClicked(String id);
}
In your activity create a callback and pass it to your adapter like this:
ClickCallback callback = new ClickCallback() {
#Override
public void onItemClicked(String id) {
//your list item object must have a method to get color
color = yourDataList.get(id).getColor();
}
};
protected void onSaveInstanceState(Bundle bundle) {
super.onSaveInstanceState(bundle);
bundle.putInt("color", color);
}
YourAdapter adapter = new YourAdapter (yourDataList, callback)
In your adapter don't forget to set OnClickListener and call appropriate method, it could be like this:
public ListItemViewHolder(View itemView) {
super(itemView);
//your code
itemView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
callback.onItemClicked(getAdapterPosition());
}
});
}
}
In OnCreate extract your color data:
public void onCreate(Bundle bundle) {
if (bundle != null) {
value = bundle.getInt("color");
}
}

You can store statuses of each square in a proper format and save them
on onSaveInstanceState and retrieve them on onCreate method and manipulate the adapter as for your requirement.
Read more...
Hope this helps!

"But when screen orientate, view is refreshing."
on screen rotation a new instance of the activity is created
You can have a ViewModel class which stores your arraylist of data including their current state. When activity is recreated via rotation this will be persisted and you will get the correct state.
Ref : https://medium.com/androiddevelopers/viewmodels-a-simple-example-ed5ac416317e

How to disable animation for ListAdapter

I am using new ListAdapter, which automatically animates changes. I would like to disable animations or enable/disable it programmatically.
class UserAdapter extends ListAdapter<User, UserViewHolder> {
public UserAdapter() {
super(User.DIFF_CALLBACK);
}
#Override
public void onBindViewHolder(UserViewHolder holder, int position) {
holder.bindTo(getItem(position));
}
public static final DiffUtil.ItemCallback<User> DIFF_CALLBACK =
new DiffUtil.ItemCallback<User>() {
#Override
public boolean areItemsTheSame(
#NonNull User oldUser, #NonNull User newUser) {
// User properties may have changed if reloaded from the DB, but ID is fixed
return oldUser.getId() == newUser.getId();
}
#Override
public boolean areContentsTheSame(
#NonNull User oldUser, #NonNull User newUser) {
// NOTE: if you use equals, your object must properly override Object#equals()
// Incorrectly returning false here will result in too many animations.
return oldUser.equals(newUser);
}
}
}

Another solution is to simply remove the item animator altogether.
recyclerView.itemAnimator = null

You could try to disable or enable animations with setSupportsChangeAnimations on RecyclerView item animator:
SimpleItemAnimator itemAnimator = (SimpleItemAnimator) recyclerView.getItemAnimator();
itemAnimator.setSupportsChangeAnimations(false);

Solution which bypasses DiffUtil
Setting itemAnimator to null and calling submitList() still runs DiffUtil.ItemCallback in a background thread and doesn't submit the list on the same frame! If you want the same behaviour as calling notifyDataSetChanged(), you can do this:
adapter.submitList(null)
adapter.submitList(newItems)
This is useful if you know the contents are indeed completely different and don't care if you loose the scroll position. Or if you have multiple RecyclerViews that all have to update on the same frame (to reduce screen flashing).
Why does this work?
Looking at the source code of AsyncListDiffer.submitList():
// fast simple remove all
if (newList == null) {
//noinspection ConstantConditions
int countRemoved = mList.size();
mList = null;
mReadOnlyList = Collections.emptyList();
// notify last, after list is updated
mUpdateCallback.onRemoved(0, countRemoved);
onCurrentListChanged(previousList, commitCallback);
return;
}
// fast simple first insert
if (mList == null) {
mList = newList;
mReadOnlyList = Collections.unmodifiableList(newList);
// notify last, after list is updated
mUpdateCallback.onInserted(0, newList.size());
onCurrentListChanged(previousList, commitCallback);
return;
}
When you call submitList() the first time, all items are immediately removed. The second time they are immediately inserted, never calling DiffUtil or starting a background thread computation.
Putting it all together
if(animations) {
adapter.submitList(newItems)
} else {
recyclerView.itemAnimator = null
adapter.submitList(null)
adapter.submitList(newItems) {
recyclerView.post {
//Restore the default item animator
recyclerView.itemAnimator = DefaultItemAnimator()
}
}
}

How to reset recyclerView position item views to original state after refreshing adapter

I have a RecyclerView with rows that have views that when clicked will be disabled for that row position.
The problem is after I update the adapter like this:
adapterData.clear();
adapterData.addAll(refreshedAdapterData);
notifyDataSetChanged();
After refreshing the data, the disabled views at the previous recycler position still remain disabled even though the data is refreshed.
How can I reset the views to the original state after refreshing adapter data.

Use below code.
adapterData.clear();
adapterData.addAll(refreshedAdapterData);
adapter.notifyDataSetChanged();
OR
recyclerView.invalidate();

When you call notifyDataSetChanged(), the onBindViewHolder() method of every view is called. So you could add something like this in the onBindViewHolder() of your Adapter method:
#Override
public void onBindViewHolder(final RecyclerView.ViewHolder viewHolder, final int position) {
if (refreshedAdapterData.get(position).isInDefaultState()) {
//set Default View Values
} else {
//the code you already have
}
}

I have resolved this by putting a conditional statement inside onBindViewHolder method instructing all positions to reset the disabled views if data meets the required conditions for a refreshed data.
#Christoph Mayr, thanks for your comments. It helped point me in the right direction.

I cleared the data then notify change but the selected checkbox doesn't reset but just moves up one position. Let say I selected item #1 , move out of the RecyclerView, came back and it will auto select item #0.
So, I created new adapter again at onResume(), i worked for me but i don't know if it's the right way to handle this situation.
#Override
public void onResume() {
super.onResume();
if(selectedItems != null && selectedItems.size() > 0){
selectedItems.clear(); // if no selected items before then no need to reset anything
if(adapter != null && recyclerView != null){
// to remove the checked box
adapter = null;
adapter = new MyAdapter(items, new MyAdapter.MyAdapterListener() {
#Override
public void onSelected(int pos) {
selectedItems.add(items.get(pos));
}
#Override
public void onUnSelected(int pos) {
selectedItems.remove(items.get(pos));
}
});
recyclerView.setAdapter(adapter);
}
}
}

How to save scroll position of RecyclerView in Android?

I have Recycler view which lays inside of SwipeRefreshLayout. Also, have ability to open each item in another activity.
After returning back to Recycler I need scroll to chosen item, or to previous Y.
How to do that?
Yes, I googled, found articles in StackOverFlow about saving instance of layout manager, like this one: RecyclerView store / restore state between activities.
But, it doesn't help me.
UPDATE
Right now I have this kind of resolving problem, but, of course, it also doesn't work.
private int scrollPosition;
...//onViewCreated - it is fragment
recyclerView.setHasFixedSize(true);
LinearLayoutManager llm = new LinearLayoutManager(getActivity());
recyclerView.setLayoutManager(llm);
data = new ArrayList<>();
adapter.setData(getActivity(), data);
recyclerView.setAdapter(adapter);
...
#Override
public void onResume() {
super.onResume();
recyclerView.setScrollY(scrollPosition);
}
#Override
public void onPause() {
super.onPause();
scrollPosition = recyclerView.getScrollY();
}
Yes, I have tried scrollTo(int, int) - doen't work.
Now I tried just scroll, for example, to Y = 100, but it doesn't scrolling at all.

Save the current state of recycle view position #onPause:
positionIndex= llManager.findFirstVisibleItemPosition();
View startView = rv.getChildAt(0);
topView = (startView == null) ? 0 : (startView.getTop() - rv.getPaddingTop());
Restore the scroll position #onResume:
if (positionIndex!= -1) {
llManager.scrollToPositionWithOffset(positionIndex, topView);
}
or another way can be #onPause:
long currentVisiblePosition = 0;
currentVisiblePosition = ((LinearLayoutManager)rv.getLayoutManager()).findFirstCompletelyVisibleItemPosition();
restore #onResume:
((LinearLayoutManager) rv.getLayoutManager()).scrollToPosition(currentVisiblePosition);
currentVisiblePosition = 0;

A lot of these answers seem to be over complicating it.
The LayoutManager supports onRestoreInstanceState out of the box so there is no need to save scroll positions etc. The built in method already saves pixel perfect positions.
example fragment code (null checking etc removed for clarity):
private Parcelable listState;
private RecyclerView list;
#Override
public void onCreate(#Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
listState=savedInstanceState.getParcelable("ListState");
}
#Override
public void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
outState.putParcelable("ListState", list.getLayoutManager().onSaveInstanceState());
}
then just call
list.getLayoutManager().onRestoreInstanceState(listState);
once your data has been reattached to your RecyclerView

Beginning from version 1.2.0-alpha02 of androidx recyclerView library, it is now automatically managed. Just add it with:
implementation "androidx.recyclerview:recyclerview:1.2.0-alpha02"
And use:
adapter.stateRestorationPolicy = StateRestorationPolicy.PREVENT_WHEN_EMPTY
The StateRestorationPolicy enum has 3 options:
ALLOW — the default state, that restores the RecyclerView state immediately, in the next layout pass
PREVENT_WHEN_EMPTY — restores the RecyclerView state only when the adapter is not empty (adapter.getItemCount() > 0). If your data is loaded async, the RecyclerView waits until data is loaded and only then the state is restored. If you have default items, like headers or load progress indicators as part of your Adapter, then you should use the PREVENT option, unless the default items are added using MergeAdapter. MergeAdapter waits for all of its adapters to be ready and only then it restores the state.
PREVENT — all state restoration is deferred until you set ALLOW or PREVENT_WHEN_EMPTY.
Note that at the time of this answer, recyclerView library is still in alpha03, but alpha phase is not suitable for production purposes.

User your recycler view linearlayoutmanager for getting scroll position
int position = 0;
if (linearLayoutManager != null) {
scrollPosition = inearLayoutManager.findFirstVisibleItemPosition();
}
and when restoring use following code
if (linearLayoutManager != null) {
cardRecyclerView.scrollToPosition(mScrollPosition);
}
Hope this helps you

to save position to Preferences, add this to your onStop()
int currentVisiblePosition = ((LinearLayoutManager) recyclerView.getLayoutManager()).findFirstCompletelyVisibleItemPosition();
getPreferences(MODE_PRIVATE).edit().putInt("listPosition", currentVisiblePosition).apply();
then restore position like this
if (getItemCount() == 0) {
int savedListPosition = getPreferences(MODE_PRIVATE).getInt("listPosition", 0);
recyclerView.getLayoutManager().scrollToPosition(savedListPosition); }
this last code should be added inside an event of the Adapter (not sure witch event but in my case was onEvent() - com.google.firebase.firestore.EventListener)

For some reason there are a lot of quite misleading tips/suggestions on how to save and restore scroll position in your_scrolling_container upon orientation changes.
Taking current scroll position and saving it in Activity’s onSaveInstanceState
Extending a certain scrollable View to do same there
Preventing Activity from being destroyed on rotation
And yeah, they are working fine, but…
But in fact, everything is much simpler, because Android is already doing it for you!
If you take a closer look at
RecyclerView/ListView/ScrollView/NestedScrollView sources, you’ll see that each of them is saving its scroll position in onSaveInstanceState. And during the first layout pass they are trying to scroll to this position in onLayout method.
There are only 2 things you need to do, to make sure it’s gonna work fine:
Set an id for your scrollable view, which is probably already done. Otherwise Android won’t be able to save View state automatically.
Provide a data before the first layout pass, to have the same scroll boundaries you had before rotation. That’s the step where developers usually have some issues.

The easiest and transition compatible way I found is:
#Override
public void onPause() {
super.onPause();
recyclerView.setLayoutFrozen(true);
}
#Override
public void onResume() {
super.onResume();
recyclerView.setLayoutFrozen(false);
}

in onSaveInstanceState() method of fragment you can save the scroll position of RecycleView
#Override
public void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
LinearLayoutManager layoutManager = (LinearLayoutManager)
recyclerView.getLayoutManager();
outState.putInt("scrolled_position",
layoutManager.findFirstCompletelyVisibleItemPosition());
}
then you can retrieve saved scroll position in onViewStateRestored() method
#Override
public void onViewStateRestored(#Nullable Bundle savedInstanceState) {
super.onViewStateRestored(savedInstanceState);
if (savedInstanceState != null) {
int scrollPosition = savedInstanceState.getInt("scrolled_position");
recyclerView.scrollToPosition(scrollPosition);
}
}

You can use scrollToPosition or smoothScrollToPosition to scroll to any item position in RecyclerView.
If you want to scroll to item position in adapter, then you would have to use adapter's scrollToPosition or smoothScrollToPosition.

Refreshing data in RecyclerView and keeping its scroll position

How does one refresh the data displayed in RecyclerView (calling notifyDataSetChanged on its adapter) and make sure that the scroll position is reset to exactly where it was?
In case of good ol' ListView all it takes is retrieving getChildAt(0), checking its getTop() and calling setSelectionFromTop with the same exact data afterwards.
It doesn't seem to be possible in case of RecyclerView.
I guess I'm supposed to use its LayoutManager which indeed provides scrollToPositionWithOffset(int position, int offset), but what's the proper way to retrieve the position and the offset?
layoutManager.findFirstVisibleItemPosition() and layoutManager.getChildAt(0).getTop()?
Or is there a more elegant way to get the job done?

I use this one.^_^
// Save state
private Parcelable recyclerViewState;
recyclerViewState = recyclerView.getLayoutManager().onSaveInstanceState();
// Restore state
recyclerView.getLayoutManager().onRestoreInstanceState(recyclerViewState);
It is simpler, hope it will help you!

I have quite similar problem. And I came up with following solution.
Using notifyDataSetChanged is a bad idea. You should be more specific, then RecyclerView will save scroll state for you.
For example, if you only need to refresh, or in other words, you want each view to be rebinded, just do this:
adapter.notifyItemRangeChanged(0, adapter.getItemCount());

EDIT: To restore the exact same apparent position, as in, make it look exactly like it did, we need to do something a bit different (See below how to restore the exact scrollY value):
Save the position and offset like this:
LinearLayoutManager manager = (LinearLayoutManager) mRecycler.getLayoutManager();
int firstItem = manager.findFirstVisibleItemPosition();
View firstItemView = manager.findViewByPosition(firstItem);
float topOffset = firstItemView.getTop();
outState.putInt(ARGS_SCROLL_POS, firstItem);
outState.putFloat(ARGS_SCROLL_OFFSET, topOffset);
And then restore the scroll like this:
LinearLayoutManager manager = (LinearLayoutManager) mRecycler.getLayoutManager();
manager.scrollToPositionWithOffset(mStatePos, (int) mStateOffset);
This restores the list to its exact apparent position. Apparent because it will look the same to the user, but it will not have the same scrollY value (because of possible differences in landscape/portrait layout dimensions).
Note that this only works with LinearLayoutManager.
--- Below how to restore the exact scrollY, which will likely make the list look different ---
Apply an OnScrollListener like so:
private int mScrollY;
private RecyclerView.OnScrollListener mTotalScrollListener = new RecyclerView.OnScrollListener() {
#Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
super.onScrolled(recyclerView, dx, dy);
mScrollY += dy;
}
};
This will store the exact scroll position at all times in mScrollY.
Store this variable in your Bundle, and restore it in state restoration to a different variable, we'll call it mStateScrollY.
After state restoration and after your RecyclerView has reset all its data reset the scroll with this:
mRecyclerView.scrollBy(0, mStateScrollY);
That's it.
Beware, that you restore the scroll to a different variable, this is important, because the OnScrollListener will be called with .scrollBy() and subsequently will set mScrollY to the value stored in mStateScrollY. If you do not do this mScrollY will have double the scroll value (because the OnScrollListener works with deltas, not absolute scrolls).
State saving in activities can be achieved like this:
#Override
protected void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
outState.putInt(ARGS_SCROLL_Y, mScrollY);
}
And to restore call this in your onCreate():
if(savedState != null){
mStateScrollY = savedState.getInt(ARGS_SCROLL_Y, 0);
}
State saving in fragments works in a similar way, but the actual state saving needs a bit of extra work, but there are plenty of articles dealing with that, so you shouldn't have a problem finding out how, the principles of saving the scrollY and restoring it remain the same.

Keep scroll position by using #DawnYu answer to wrap notifyDataSetChanged() like this:
val recyclerViewState = recyclerView.layoutManager?.onSaveInstanceState()
adapter.notifyDataSetChanged()
recyclerView.layoutManager?.onRestoreInstanceState(recyclerViewState)

Yes you can resolve this issue by making the adapter constructor only one time, I am explaining the coding part here :
if (appointmentListAdapter == null) {
appointmentListAdapter = new AppointmentListAdapter(AppointmentsActivity.this);
appointmentListAdapter.addAppointmentListData(appointmentList);
appointmentListAdapter.setOnStatusChangeListener(onStatusChangeListener);
appointmentRecyclerView.setAdapter(appointmentListAdapter);
} else {
appointmentListAdapter.addAppointmentListData(appointmentList);
appointmentListAdapter.notifyDataSetChanged();
}
Now you can see I have checked the adapter is null or not and only initialize when it is null.
If adapter is not null then I am assured that I have initialized my adapter at least one time.
So I will just add list to adapter and call notifydatasetchanged.
RecyclerView always holds the last position scrolled, therefore you don't have to store last position, just call notifydatasetchanged, recycler view always refresh data without going to top.
Thanks
Happy Coding

The top answer by #DawnYu works, but the recyclerview will first scroll to the top, then go back to the intended scroll position causing a "flicker like" reaction which isn't pleasant.
To refresh the recyclerView, especially after coming from another activity, without flickering, and maintaining the scroll position, you need to do the following.
Ensure you are updating you recycler view using DiffUtil. Read more about that here: https://www.journaldev.com/20873/android-recyclerview-diffutil
Onresume of your activity, or at the point you want to update your activity, load data to your recyclerview. Using the diffUtil, only the updates will be made on the recyclerview while maintaining it position.
Hope this helps.

Here is an option for people who use DataBinding for RecyclerView.
I have var recyclerViewState: Parcelable? in my adapter. And I use a BindingAdapter with a variation of #DawnYu's answer to set and update data in the RecyclerView:
#BindingAdapter("items")
fun setRecyclerViewItems(
recyclerView: RecyclerView,
items: List<RecyclerViewItem>?
) {
var adapter = (recyclerView.adapter as? RecyclerViewAdapter)
if (adapter == null) {
adapter = RecyclerViewAdapter()
recyclerView.adapter = adapter
}
adapter.recyclerViewState = recyclerView.layoutManager?.onSaveInstanceState()
// the main idea is in this call with a lambda. It allows to avoid blinking on data update
adapter.submitList(items.orEmpty()) {
adapter.recyclerViewState?.let {
recyclerView.layoutManager?.onRestoreInstanceState(it)
}
}
}
Finally, the XML part looks like:
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/possible_trips_rv"
android:layout_width="match_parent"
android:layout_height="0dp"
app:items="#{viewState.yourItems}"
app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager"/>

I was making a mistake like this, maybe it will help someone :)
If you use recyclerView.setAdapter every time new data come, it calls the adapter clear() method every time you use it, which causes the recyclerview to refresh and start over. To get rid of this, you need to use adapter.notiftyDatasetChanced().

1- You need to save scroll position like this
rvProduct.addOnScrollListener(new RecyclerView.OnScrollListener() {
#Override
public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
super.onScrollStateChanged(recyclerView, newState);
recyclerViewState = rvProduct.getLayoutManager().onSaveInstanceState(); // save recycleView state
}
});
2- And after you call notifyDataSetChanged then onRestoreInstanceState like this example
productsByBrandAdapter.addData(productCompareList);
productsByBrandAdapter.notifyDataSetChanged();
rvProduct.getLayoutManager().onRestoreInstanceState(recyclerViewState); // restore recycleView state

I have not used Recyclerview but I did it on ListView. Sample code in Recyclerview:
setOnScrollListener(new RecyclerView.OnScrollListener() {
#Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
rowPos = mLayoutManager.findFirstVisibleItemPosition();
It is the listener when user is scrolling. The performance overhead is not significant. And the first visible position is accurate this way.

Create Extention and use it entirely your App, if you are using DiffUtil you don't need to add adapter.notifyDataSetChanged()
fun RecyclerView.reStoreState(){
val recyclerViewState = this.layoutManager?.onSaveInstanceState()
this.layoutManager?.onRestoreInstanceState(recyclerViewState)
}
Then use it like this below
yourRecyclerView.reStoreState()
adapter.submitList(yourData)
yourRecyclerView.adapter = adapter

#BindingAdapter("items")
fun <T> RecyclerView.setItems(items: List<T>?) {
(adapter as? ListAdapter<T, *>)?.submitList(items) {
layoutManager?.onSaveInstanceState().let {
layoutManager?.onRestoreInstanceState(it)
}
}
}

mMessageAdapter.registerAdapterDataObserver(new RecyclerView.AdapterDataObserver() {
#Override
public void onChanged() {
mLayoutManager.smoothScrollToPosition(mMessageRecycler, null, mMessageAdapter.getItemCount());
}
});
The solution here is to keep on scrolling recyclerview when new message comes.
The onChanged() method detects the action performed on recyclerview.

That's working for me in Kotlin.
Create the Adapter and hand over your data in the constructor
class LEDRecyclerAdapter (var currentPole: Pole): RecyclerView.Adapter<RecyclerView.ViewHolder>() { ... }
change this property and call notifyDataSetChanged()
adapter.currentPole = pole
adapter.notifyDataSetChanged()
The scroll offset doesn't change.

If you have one or more EditTexts inside of a recyclerview items, disable the autofocus of these, putting this configuration in the parent view of recyclerview:
android:focusable="true"
android:focusableInTouchMode="true"
I had this issue when I started another activity launched from a recyclerview item, when I came back and set an update of one field in one item with notifyItemChanged(position) the scroll of RV moves, and my conclusion was that, the autofocus of EditText Items, the code above solved my issue.
best.

Just return if the oldPosition and position is same;
private int oldPosition = -1;
public void notifyItemSetChanged(int position, boolean hasDownloaded) {
if (oldPosition == position) {
return;
}
oldPosition = position;
RLog.d(TAG, " notifyItemSetChanged :: " + position);
DBMessageModel m = mMessages.get(position);
m.setVideoHasDownloaded(hasDownloaded);
notifyItemChanged(position, m);
}

I had this problem with a list of items which each had a time in minutes until they were 'due' and needed updating. I'd update the data and then after, call
orderAdapter.notifyDataSetChanged();
and it'd scroll to the top every time. I replaced that with
for(int i = 0; i < orderArrayList.size(); i++){
orderAdapter.notifyItemChanged(i);
}
and it was fine. None of the other methods in this thread worked for me. In using this method though, it made each individual item flash when it was updated so I also had to put this in the parent fragment's onCreateView
RecyclerView.ItemAnimator animator = orderRecycler.getItemAnimator();
if (animator instanceof SimpleItemAnimator) {
((SimpleItemAnimator) animator).setSupportsChangeAnimations(false);
}