Refreshing data in RecyclerView and keeping its scroll position

Question

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

User · Answer

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 lt RecyclerView ViewHolder gt                change this property and call notifyDataSetChanged     adapter currentPole   pole adapter notifyDataSetChanged     The scroll offset doesn t change

User · Answer

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

User · Answer

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

User · Answer

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

User · Answer

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

User · Answer

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

User · Answer

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

User · Answer

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

User · Answer

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  lt  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

User · Answer

Keep scroll position by using  DawnYu answer to wrap notifyDataSetChanged   like this   val recyclerViewState   recyclerView layoutManager  onSaveInstanceState    adapter notifyDataSetChanged    recyclerView layoutManager  onRestoreInstanceState recyclerViewState

User · Answer

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

User · Answer

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  quot items quot   fun setRecyclerViewItems      recyclerView  RecyclerView      items  List lt RecyclerViewItem gt           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   lt androidx recyclerview widget RecyclerView     android id  quot   id possible trips rv quot      android layout width  quot match parent quot      android layout height  quot 0dp quot      app items  quot   viewState yourItems  quot      app layoutManager  quot androidx recyclerview widget LinearLayoutManager quot   gt

User · Answer

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

User · Answer

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

User · Answer

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

[android] Refreshing data in RecyclerView and keeping its scroll position

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