如何滚动到 RecyclerView 的底部？ scrollToPosition 不起作用

Question

I'd like to scroll to the bottom of the RecyclerView list after loading the activity.

GENERIC_MESSAGE_LIST = (ArrayList) intent.getExtras().getParcelableArrayList(ConversationsAdapter.EXTRA_MESSAGE);
conversationView = (RecyclerView) findViewById(R.id.list_messages);
conversationView.setHasFixedSize(true);
conversationViewLayoutManager = new LinearLayoutManager(this);
conversationView.setLayoutManager(conversationViewLayoutManager);
conversationViewAdapter = new ConversationAdapter(GENERIC_MESSAGE_LIST, this);
conversationView.setAdapter(conversationViewAdapter);

conversationView.scrollTo(...) throws an exception about being not supported in RecyclerView, and conversationView.scrollToPosition(...) doesn't seem to do anything.

After the above block of code, I added

conversationView.scrollToPosition(GENERIC_MESSAGE_LIST.size() + 1)

which doesn't work. There are 30 elements in GENERIC_MESSAGE_LIST .

Answer 1

I was looking at this post to find the answer but... I think everyone on this post was facing the same scenario as me: scrollToPosition() was fully ignored, for an evident reason.

What I was using?

recyclerView.scrollToPosition(items.size());

... what WORKED ?

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

Answer 2

Just set setStackFromEnd=true or setReverseLayout=true so that LLM will layout items from end.

The difference between these two is that setStackFromEnd will set the view to show the last element, the layout direction will remain the same. (So, in an left-to-right horizontal Recycler View, the last element will be shown and scrolling to the left will show the earlier elements)

Whereas setReverseLayout will change the order of the elements added by the Adapter. The layout will start from the last element, which will be the left-most in an LTR Recycler View and then, scrolling to the right will show the earlier elements.

Sample:

final LinearLayoutManager linearLayoutManager = new LinearLayoutManager(getActivity());
linearLayoutManager.setReverseLayout(true);
_listView.setLayoutManager(linearLayoutManager);

See documentation for details.

Answer 3

我知道在这里回答晚了，如果有人想知道下面的解决方案

conversationView.smoothScrollToPosition(conversationView.getAdapter().getItemCount() - 1);

Answer 4

To scrolldown from any position in the recyclerview to bottom

Kotlin

editText.setOnClickListener {
    rv.postDelayed({                 
        rv.scrollToPosition(rv.adapter.itemCount - 1)
    }, 1000)
}

Java

edittext.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                rv.postDelayed(new Runnable() {
                    @Override
                    public void run() {
                      rv.scrollToPosition(rv.getAdapter().getItemCount() - 1);
                    }
                }, 1000);
            }
        });

Answer 5

在发送消息之后和从服务器获取消息之前添加此代码

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

Answer 6

When you call setAdapter , that does not immediately lay out and position items on the screen (that takes a single layout pass) hence your scrollToPosition() call has no actual elements to scroll to when you call it.

Instead, you should register a ViewTreeObserver.OnGlobalLayoutListener (via addOnGlobalLayoutListner() from a ViewTreeObserver created by conversationView.getViewTreeObserver() ) which delays your scrollToPosition() until after the first layout pass:

conversationView.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
  public void onGlobalLayout() {
    conversationView.scrollToPosition(GENERIC_MESSAGE_LIST.size();
    // Unregister the listener to only call scrollToPosition once
    conversationView.getViewTreeObserver().removeGlobalOnLayoutListener(this);

    // Use vto.removeOnGlobalLayoutListener(this) on API16+ devices as 
    // removeGlobalOnLayoutListener is deprecated.
    // They do the same thing, just a rename so your choice.
  }
});

Answer 7

Solution for Kotlin :

apply below code after setting "recyclerView.adapter" or after "recyclerView.adapter.notifyDataSetChanged()"

recyclerView.scrollToPosition(recyclerView.adapter.itemCount - 1)

Answer 8

如果您的适配器与 recyclerView 相连，则只需执行此操作。

mRecyclerView.smoothScrollToPosition(mRecyclerView.getAdapter().getItemCount());

Answer 9

class MyLayoutManager extends LinearLayoutManager {

  public MyLayoutManager(Context context) {
    super(context, LinearLayoutManager.VERTICAL, false);
  }

  @Override public void smoothScrollToPosition(RecyclerView recyclerView,
      final RecyclerView.State state, final int position) {

    int fcvip = findFirstCompletelyVisibleItemPosition();
    int lcvip = findLastCompletelyVisibleItemPosition();

    if (position < fcvip || lcvip < position) {
      // scrolling to invisible position

      float fcviY = findViewByPosition(fcvip).getY();
      float lcviY = findViewByPosition(lcvip).getY();

      recyclerView.setOnScrollListener(new RecyclerView.OnScrollListener() {

        int currentState = RecyclerView.SCROLL_STATE_IDLE;

        @Override public void onScrollStateChanged(RecyclerView recyclerView, int newState) {

          if (currentState == RecyclerView.SCROLL_STATE_SETTLING
              && newState == RecyclerView.SCROLL_STATE_IDLE) {

            // recursive scrolling
            smoothScrollToPosition(recyclerView, state, position);
          }

          currentState = newState;
        }

        @Override public void onScrolled(RecyclerView recyclerView, int dx, int dy) {

          int fcvip = findFirstCompletelyVisibleItemPosition();
          int lcvip = findLastCompletelyVisibleItemPosition();

          if ((dy < 0 && fcvip == position) || (dy > 0 && lcvip == position)) {
            // stop scrolling
            recyclerView.setOnScrollListener(null);
          }
        }
      });

      if (position < fcvip) {
        // scroll up

        recyclerView.smoothScrollBy(0, (int) (fcviY - lcviY));
      } else {
        // scroll down

        recyclerView.smoothScrollBy(0, (int) (lcviY - fcviY));
      }
    } else {
      // scrolling to visible position

      float fromY = findViewByPosition(fcvip).getY();
      float targetY = findViewByPosition(position).getY();

      recyclerView.smoothScrollBy(0, (int) (targetY - fromY));
    }
  }
}

and

MyLayoutManager layoutManager = new MyLayoutManager(context);
recyclerView.setLayoutManager(layoutManager);

RecyclerView.Adapter adapter = new YourAdapter();
recyclerView.setAdapter(adapter);

recyclerView.smoothScrollToPosition(adapter.getItemCount() - 1);

above code works, but it's not smooth and not cool.

Answer 10

In Kotlin:

recyclerView.viewTreeObserver.addOnGlobalLayoutListener { scrollToEnd() }

private fun scrollToEnd() =
        (adapter.itemCount - 1).takeIf { it > 0 }?.let(recyclerView::smoothScrollToPosition)

Answer 11

Roc answer is a great help. I would like to add a small block to it:

mRecyclerView.scrollToPosition(mAdapter.getItemCount() - 1);

Answer 12

在我的情况下，视图没有相同的高度， 在 LayoutManager 上调用scrollToPosition可以真正滚动到底部并完全看到最后一个项目：

recycler.getLayoutManager().scrollToPosition(adapter.getItemCount() - 1);

Answer 13

First time scroll when entering in recycler view first time then use

linearLayoutManager.scrollToPositionWithOffset(messageHashMap.size()-1

put in minus for scroll down for scroll up put in positive value);

if the view is very big in height then scrolltoposition particular offset is used for the top of view then you use

int overallXScroldl =chatMessageBinding.rvChat.computeVerticalScrollOffset();
chatMessageBinding.rvChat.smoothScrollBy(0, Math.abs(overallXScroldl));

Answer 14

This works perfectly fine for me:

AdapterChart adapterChart = new AdapterChart(getContext(),messageList);
recyclerView.setAdapter(adapterChart);
recyclerView.scrollToPosition(recyclerView.getAdapter().getItemCount()-1);

Answer 15

The answer is

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

Everyone has mentioned it.

But the problem I was facing was that it was not placed correctly .

I tried and placed just after the adapter.notifyDataSetChanged(); and it worked. Whenever, data in your recycler view changes, it automatically scrolls to the bottom like after sending messages or you open the chat list for the first time.

Note : This code was tasted in Java.

actual code for me was :

//scroll to bottom after sending message.
binding.chatRecyclerView.scrollToPosition(messageArrayList.size() - 1);

Answer 16

If you are having issues making recyclerview scroll to the latest, check that the recyclerview is not inside a nestedScrollView. That was my issue. I had to remove the nestedScrollview and then the below code worked.

binding.recyclerView.scrollToPosition(adapter.getItemCount() - 1);

Answer 17

this code will give you latest post first, i think this answer is helpful.

    mInstaList=(RecyclerView)findViewById(R.id.insta_list);
    mInstaList.setHasFixedSize(true);

    LinearLayoutManager layoutManager = new LinearLayoutManager(this);
    layoutManager.setOrientation(LinearLayoutManager.VERTICAL);

    mInstaList.setLayoutManager(layoutManager);
    layoutManager.setStackFromEnd(true);
    layoutManager.setReverseLayout(true);

Answer 18

Tried a method of @galex , it worked until refactoring. So I used an answer of @yanchenko and changed a bit. Probably this is because I called scrolling from onCreateView() , where a fragment view was built (and probably didn't have right size).

private fun scrollPhotosToEnd(view: View) {
    view.recycler_view.viewTreeObserver.addOnGlobalLayoutListener(object :
        ViewTreeObserver.OnGlobalLayoutListener {
        override fun onGlobalLayout() {
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {
                view.recycler_view.viewTreeObserver.removeOnGlobalLayoutListener(this)
            } else {
                @Suppress("DEPRECATION")
                view.recycler_view.viewTreeObserver.removeGlobalOnLayoutListener(this)
            }
            adapter?.itemCount?.takeIf { it > 0 }?.let {
                view.recycler_view.scrollToPosition(it - 1)
            }
        }
    })
}

You can also add a check of viewTreeObserver.isAlive like in https://stackoverflow.com/a/39001731/2914140 .

Answer 19

如果你正在使用他，你必须在scrollToPosition之前隐藏AppBarLayout

Answer 20

You can scroll to the bottom of the last item, if the height of the last item is too large, you need to offset

 private void scrollToBottom(final RecyclerView recyclerView) {
        // scroll to last item to get the view of last item
        final LinearLayoutManager layoutManager = (LinearLayoutManager) recyclerView.getLayoutManager();
        final RecyclerView.Adapter adapter = recyclerView.getAdapter();
        final int lastItemPosition = adapter.getItemCount() - 1;
    
        layoutManager.scrollToPositionWithOffset(lastItemPosition, 0);
        recyclerView.post(new Runnable() {
            @Override
            public void run() {
                // then scroll to specific offset
                View target = layoutManager.findViewByPosition(lastItemPosition);
                if (target != null) {
                    int offset = recyclerView.getMeasuredHeight() - target.getMeasuredHeight();
                    layoutManager.scrollToPositionWithOffset(lastItemPosition, offset);
                }
            }
        });



    }

Answer 21

Only Ian's answer was able to make my RecyclerView scroll to a specified position. However, The RecyclerView was not able to scroll afterwards when I used scrollToPosition() . smoothScrollToPosition() worked but the initial animation made it too slow when the list was long. The reason was the listener was not removed. I used the code below to remove the current ViewTreeObserver and it worked as a charm.

    mRecyclerView.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
        @Override
        public void onGlobalLayout() {
            mRecyclerView.scrollToPosition(mPosition);
            mRecyclerView.getViewTreeObserver().removeOnGlobalLayoutListener(this);
        }
    });

Answer 22

If none of these worked,

you should try to use :

ConstraintLayout targetView = (ConstraintLayout) recyclerView.findViewHolderForAdapterPosition(adapter.getItemCount()-1).itemView;
targetView.getParent().requestChildFocus(targetView, targetView);

By doing this, you are requesting a certain ConstraintLayout (Or whatever you have) to be displayed. The scroll is instant.

I works even with keyboard shown.

Answer 23

If you want just starting from the end use:

layoutManager.stackFromEnd = true

(Kotlin solution)

Answer 24

I know this is too late but this worked for me so that i am answering this question

first,

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

after that,

database.addValueEventListener(....){
@override
public void onDataCange(...){
....
....
//put this line here
recyclerView.smoothScrollToPosition(recyclerView.getAdapter().getItemCount()-1);
}
}

Answer 25

if you use kotlin, try this

conversationView.post {
    scrollToPosition(conversationView?.adapter.itemCount - 1)
}

Answer 26

If you working with reversedLayout "chat interface" specially if you have images, you can try the following:

first, register DataObserver with the adapter

   chatAdapter.registerAdapterDataObserver(object : 
                         RecyclerView.AdapterDataObserver() {

   override fun onItemRangeInserted(positionStart: Int itemCount: Int) {

      val messageCount: Int = chatAdapter.itemCount

      val lastVisiblePosition: Int =
            layoutManager.findLastCompletelyVisibleItemPosition()

         if (lastVisiblePosition == -1 || positionStart <= (messageCount - 1)) {
            recyclerView.scrollToPosition(positionStart)
        }
    }
}) 

this will be called once you set the data for the adapter

second, you have to add a scroll listener to the recyclerView like this:

   recyclerView.addOnScrollListener(object 
     :RecyclerView.OnScrollListener() {

       override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: 
          Int) {
            super.onScrolled(recyclerView, dx, dy)

          val lastVisiblePosition: Int =
              layoutManager.findLastCompletelyVisibleItemPosition()
        if (lastVisiblePosition != -1 && lastVisiblePosition < 
                chatAdapter.itemCount - 1) {
            recyclerView.smoothScrollToPosition(0)
        }
    }
})

Answer 27

use video_frames?.smoothScrollToPosition(pos.toInt())

this work for me*

Answer 28

use only gravity for easy solution

android:layout_gravity="bottom"