RecyclerView scroll to position when a new item is added

Question

I want my RecyclerView to scroll to the bottom when a new item is added to the list. Below is my code:

RecyclerView.LayoutManager layoutManager = new LinearLayoutManager(getActivity());
recyclerView.setLayoutManager(layoutManager);

adapter = new RecyclerViewAdapter(data, recyclerView);
recyclerView.setAdapter(adapter);

And when I click a button which is below the RecyclerView, data is added to the list:

public void addNewCard() {
    data.add("New");
    adapter.notifyItemInserted(data.size() - 1);
    recyclerView.scrollToPosition(data.size() - 1);
}

Whenever I add an item, it always gets scrolled up to the topmost position. I tried using smoothScrollToPosition() and tried using scrollToPosition() on LinearLayoutManager too. I even tried using ViewTreeObserver. Tried changing the version of RecyclerView in dependencies too. I searched thoroughly on Stack Overflow and none of the solutions work for me.

Any ideas on what could be the problem? I'm using RecyclerView inside a fragment. Could that be a cause of the problem?

My .xml file for the RecyclerView

<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.widget.NestedScrollView 
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/scroll_view_recycler"
android:layout_width="match_parent"
android:layout_height="match_parent">

<RelativeLayout
    android:id="@+id/rel_layout"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

    <android.support.v7.widget.RecyclerView
        android:id="@+id/listView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="6dp" />

    <Button
        android:id="@+id/button_add_new_card"
        style="@style/Widget.AppCompat.Button.Borderless"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@id/listView"
        android:layout_marginBottom="16dp"
        android:layout_marginTop="8dp"
        android:padding="20dp"
        android:text="+ Add new Item" />
</RelativeLayout>
</android.support.v4.widget.NestedScrollView>

@Deepa yes I'm using it inside a RelativeLayout which is inside a ScrollView — Arshad Yusuf, Nov 12 '17 at 16:14
Then try to use NestedSrollView instead of ScrollView. Or use this method for RecyclerView layoutManager.setStackFromEnd(true); — Deepa, Nov 12 '17 at 16:20
Are you using GridLayoutManager? In that case it will not support setStackFromEnd(). — Deepa, Nov 12 '17 at 16:31
Ok then try to use this in your RecyclerViewAdapter. @Override public Item getItem(int pos) { return super.getItem(getCount() - 1 - pos); } — Deepa, Nov 12 '17 at 16:35
@Deepa sorry, I don't get that. There isn't any `getItem(int pos)` method in `RecyclerView.Adapter` class to override! — Arshad Yusuf, Nov 12 '17 at 16:41
@Deepa What should I return with `getItem` method? Because there is no `Item` type. — Arshad Yusuf, Nov 12 '17 at 16:59

score 30 · Accepted Answer · answered Nov 13 '17 at 05:33

If want to add the data to the bottom of the list you need to use setStackFromEnd() in RecyclerView Layout Manager.

But first, you need to fix your Adapter. You must not pass your RecylerView to your Adapter. So the following code is wrong:

...
// This is wrong!!
adapter = new RecyclerViewAdapter(data, recyclerView);

recyclerView.setAdapter(adapter);

You need to change your Adapter constructor to only receive the data as its parameter. Something like this:

public class RecyclerViewAdapter extends RecyclerView.Adapter<RecyclerViewAdapter.ViewHolder> {

  private List<Data> mData;

  public RecyclerViewAdapter(List<Data> data) {
    this.mData = data;
  }

  ...
}

Then you can set the data to always added at the last bottom with the following code:

LinearLayoutManager linearLayoutManager = new LinearLayoutManager(this);
linearLayoutManager.setStackFromEnd(true);
recyclerView.setLayoutManager(linearLayoutManager);

adapter = new RecyclerViewAdapter(data);
recyclerView.setAdapter(adapter);

To add the new data, you better to make a new method in the adapter. Something like this:

public class RecyclerViewAdapter extends RecyclerView.Adapter<RecyclerViewAdapter.ViewHolder> {

  private List<Data> mData;
  ...

  public void addItem(Data datum) {
    mData.add(datum);
    notifyItemInserted(mData.size());
  }
}

Whenever you have adding a new data, you need to scroll to the bottom with scrollToPosition method. Something like this:

adapter.addItem(newData);
recyclerView.scrollToPosition(adapter.getItemCount() - 1);

Remember that you need to override getItemCount() in your Adapter. It should be something like this:

public class RecyclerViewAdapter extends RecyclerView.Adapter<RecyclerViewAdapter.ViewHolder> {

  private List<Data> mData;
  public RecyclerViewAdapter(List<Data> data) {
    this.mData = data;
  }

  // Return the total count of items
  @Override
  public int getItemCount() {
    return mData.size();
  }

  ...
}

Please be aware that I'm using a Data pojo as a sample here. You need to change it according to your data type.

What doesn't work? can you create a simple project just for only the RecyclerView and adapter. I'm using the above code in my project. — ישו אוהב אותך, Nov 13 '17 at 07:38
I have added my .xml file including the `RecyclerView`. Can you see if there's a problem with it? — Arshad Yusuf, Nov 13 '17 at 07:48
You are right. I created a simple project and did the same with `RecyclerView` and `RecyclerView.Adapter`. It works fine. Apparently the problem is somewhere else. I'll look at it. Thanks for your time! — Arshad Yusuf, Nov 13 '17 at 09:07
Glad it help you a little bit! Good luck on your endeavor ;) — ישו אוהב אותך, Nov 13 '17 at 09:08
Hey @ישואוהבאותך can you please help me with this https://stackoverflow.com/questions/49952965/recyclerview-horizontal-scrolling-to-left?noredirect=1#comment87861669_49952965 — , May 19 '18 at 09:10

score 12 · Answer 2 · answered Jun 12 '20 at 20:17

12

This was the solution I came up with, which was good enough for the basics, and didn't require any custom adapters.

myAdapter.registerAdapterDataObserver(object :
        RecyclerView.AdapterDataObserver() {
        override fun onItemRangeInserted(positionStart: Int, itemCount: Int) {
            myRecyclerView.scrollToPosition(positionStart)
        }
    })

answered Jun 12 '20 at 20:17

Brill Pappin

4,692
1
36
36

2

In case you are using paging, check for `positionStart != 0` and then scroll – George Shalvashvili Oct 20 '21 at 11:46

score 9 · Answer 3 · edited Jun 22 '19 at 13:10

adapter.registerAdapterDataObserver(object : RecyclerView.AdapterDataObserver() {
    override fun onItemRangeInserted(positionStart: Int, itemCount: Int) {
        super.onItemRangeInserted(positionStart, itemCount)

        val msgCount = adapter.getItemCount()
        val lastVisiblePosition = 
            linearLayoutManager.findLastCompletelyVisibleItemPosition()

        if (lastVisiblePosition == -1 || positionStart >= msgCount - 1 && 
            lastVisiblePosition == positionStart - 1) {
            recyclerView.scrollToPosition(positionStart)
        } else {
            recyclerView.scrollToPosition(adapter.getItemCount() - 1);
        }
    }
})

score 2 · Answer 4 · edited Apr 20 '19 at 19:38

2

Maybe this will help someone

@Override
public void onChildAdded(@NonNull DataSnapshot dataSnapshot, @Nullable String s) {
    if (pingAdapter != null) {

        Ping ping = dataSnapshot.getValue(Ping.class);
        pingAdapter.pings.add(ping);
        recyclerView.smoothScrollToPosition(pingAdapter.getItemCount());

        pingAdapter.notifyDataSetChanged();
    }
}

recyclerView.smoothScrollToPosition(pingAdapter.pings.size());

is even faster

edited Apr 20 '19 at 19:38

Adrian W

4,563
11
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answered Apr 20 '19 at 19:19

Koala

29
7

I can't locate **onChildAdded** or **DataSnapshot** in RecyclerView's source – VinceStyling Oct 20 '22 at 03:36
Because it is a method by com.google.firebase.database.DatabaseReference.addChildEventListener, not RecyclerView. – Koala Oct 21 '22 at 10:50

score 2 · Answer 5 · answered Jul 05 '21 at 15:41

Alternatively, if you are using ListAdapter with DiffUtill and submit new list through submitList(), you could use ListAdapter's onCurrentListChanged. For example:

override fun onCurrentListChanged(previousList: MutableList<Item>, currentList: MutableList<Item>) {
    super.onCurrentListChanged(previousList, currentList)
     //E.g. check if new item has been added
    if (currentList.size == previousList.size + 1) {
        recyclerView.scrollToPosition(currentList.size - 1)
    }
}

score 1 · Answer 6 · answered Nov 13 '17 at 09:24

ישו אוהב אותך's solution worked on other projects. But setting recyclerView.scrollToPosition() didn't work for me. This is what finally did the job:

public void addNewCard() {
    data.add("New");
    adapter.notifyItemInserted(data.size());

    scrollView.post(new Runnable() {
        @Override
        public void run() {
            scrollView.scrollTo(0,buttonAddNewItem.getTop());
        }
    });
}

score 1 · Answer 7 · edited Sep 22 '22 at 18:05

It took me quite some time to get Recycler View to scroll to show the new added item. I got it to work by adding scrollToPosition in the Observer of the list of items coming from database. Here is my approach:

viewModel.itemList.observe(this, Observer { list ->
    list?.let {
        val numNewItems = it.size - recyclerViewAdapter.itemCount
        recyclerViewAdapter.updateList(it)
        /* Scroll to top to show new item if one was added */
        if (numNewItems >  0) {
            // position could be it.size - 1 for bottom or 0 for top
            recyclerView.scrollToPosition(position)
        }
    }
})

score 0 · Answer 8 · answered Jul 19 '19 at 05:28

This is happening because your

recyclerView.scrollToPosition(data.size() - 1);

is getting called first and then the list is being initialized. You need to add this line after your recycler View view is initialized. You can add this line in a handler.

score 0 · Answer 9 · answered Oct 02 '20 at 15:13

This is working for me.

adapter.registerAdapterDataObserver(object : RecyclerView.AdapterDataObserver() {
        override fun onChanged() {
            super.onChanged()
            if (canShowLive()) wvl_log_rv.scrollToPosition(adapter.itemCount - 1)
        }
 })

Tested & Verified

RecyclerView scroll to position when a new item is added

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