How to save scroll position of RecyclerView in Android?-ThrowExceptions

Exception or error:

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.

How to solve:

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

###

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

###

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.

###

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:

  1. Set an id for your scrollable view, which is probably already done. Otherwise Android won’t be able to save View state automatically.

  2. 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);
}

###

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.

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