Scroll RecyclerView to show selected item on top

Question

I'm looking for a way to scroll a RecyclerView to show the selected item on top.

In a ListView I was able to do that by using scrollTo(x,y) and getting the top of the element that need to be centered.

Something like:

@Override
public void onItemClick(View v, int pos){
    mylistView.scrollTo(0, v.getTop());
}

The problem is that the RecyclerView returns an error when using it's scrollTo method saying

RecyclerView does not support scrolling to an absolute position

How can I scroll a RecyclerView to put the selected item at the top of the view?

Answer 1

If you are using the LinearLayoutManager or Staggered GridLayoutManager, they each have a scrollToPositionWithOffset method that takes both the position and also the offset of the start of the item from the start of the RecyclerView, which seems like it would accomplish what you need (setting the offset to 0 should align with the top).

For instance:

//Scroll item 2 to 20 pixels from the top
linearLayoutManager.scrollToPositionWithOffset(2, 20);

Answer 2

If you looking for vertical LinearLayout Manager you can achieve smooth scrolling using a custom LinearSmoothScroller:

import android.content.Context;
import android.graphics.PointF;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.LinearSmoothScroller;
import android.support.v7.widget.RecyclerView;

public class SnappingLinearLayoutManager extends LinearLayoutManager {

    public SnappingLinearLayoutManager(Context context, int orientation, boolean reverseLayout) {
        super(context, orientation, reverseLayout);
    }

    @Override
    public void smoothScrollToPosition(RecyclerView recyclerView, RecyclerView.State state,
                                       int position) {
        RecyclerView.SmoothScroller smoothScroller = new TopSnappedSmoothScroller(recyclerView.getContext());
        smoothScroller.setTargetPosition(position);
        startSmoothScroll(smoothScroller);
    }

    private class TopSnappedSmoothScroller extends LinearSmoothScroller {
        public TopSnappedSmoothScroller(Context context) {
            super(context);

        }

        @Override
        public PointF computeScrollVectorForPosition(int targetPosition) {
            return SnappingLinearLayoutManager.this
                    .computeScrollVectorForPosition(targetPosition);
        }

        @Override
        protected int getVerticalSnapPreference() {
            return SNAP_TO_START;
        }
    }
}

use an instance of the layoutmanager in recycle view and then calling recyclerView.smoothScrollToPosition(pos); will smooth scroll to selected position to top of the recycler view

Answer 3

//Scroll item pos

linearLayoutManager.scrollToPositionWithOffset(pos, 0);

Answer 4

You just need to call recyclerview.scrollToPosition(position). That's fine!

If you want to call it in adapter, just let your adapter has the instance of recyclerview or the activity or fragment which contains recyclerview,than implements the method getRecyclerview() in them.

I hope it can help you.

Answer 5

If you want to scroll automatic without show scroll motion then you need to write following code:

mRecyclerView.getLayoutManager().scrollToPosition(position);

If you want to display scroll motion then you need to add following code. =>Step 1: You need to declare SmoothScroller.

RecyclerView.SmoothScroller smoothScroller = new
                LinearSmoothScroller(this.getApplicationContext()) {
                    @Override
                    protected int getVerticalSnapPreference() {
                        return LinearSmoothScroller.SNAP_TO_START;
                    }
                };

=>step 2: You need to add this code any event you want to perform scroll to specific position. =>First you need to set target position to SmoothScroller.

smoothScroller.setTargetPosition(position);

=>Then you need to set SmoothScroller to LayoutManager.

mRecyclerView.getLayoutManager().startSmoothScroll(smoothScroller);

Answer 6

same with speed regulator

public class SmoothScrollLinearLayoutManager extends LinearLayoutManager {
private static final float MILLISECONDS_PER_INCH = 110f;
private Context mContext;

public SmoothScrollLinearLayoutManager(Context context,int orientation, boolean reverseLayout) {
    super(context,orientation,reverseLayout);
    mContext = context;
}

@Override
public void smoothScrollToPosition(RecyclerView recyclerView, RecyclerView.State state,
                                   int position) {
    RecyclerView.SmoothScroller smoothScroller = new TopSnappedSmoothScroller(recyclerView.getContext()){
        //This controls the direction in which smoothScroll looks for your view
        @Override
        public PointF computeScrollVectorForPosition(int targetPosition) {
            return new PointF(0, 1);
        }

        //This returns the milliseconds it takes to scroll one pixel.
        @Override
        protected float calculateSpeedPerPixel(DisplayMetrics displayMetrics) {
            return MILLISECONDS_PER_INCH / displayMetrics.densityDpi;
        }
    };
    smoothScroller.setTargetPosition(position);
    startSmoothScroll(smoothScroller);
}


private class TopSnappedSmoothScroller extends LinearSmoothScroller {
    public TopSnappedSmoothScroller(Context context) {
        super(context);

    }

    @Override
    public PointF computeScrollVectorForPosition(int targetPosition) {
        return SmoothScrollLinearLayoutManager.this
                .computeScrollVectorForPosition(targetPosition);
    }

    @Override
    protected int getVerticalSnapPreference() {
        return SNAP_TO_START;
    }
}
}

Answer 7

Try what worked for me cool!

Create a variable private static int displayedposition = 0;

Now for the position of your RecyclerView in your Activity.

myRecyclerView.setOnScrollListener(new RecyclerView.OnScrollListener() {
            @Override
            public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
                super.onScrollStateChanged(recyclerView, newState);
            }

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

                LinearLayoutManager llm = (LinearLayoutManager) myRecyclerView.getLayoutManager();


                displayedposition = llm.findFirstVisibleItemPosition();


            }
        });

Place this statement where you want it to place the former site displayed in your view .

LinearLayoutManager llm = (LinearLayoutManager) mRecyclerView.getLayoutManager();
        llm.scrollToPositionWithOffset(displayedposition , youList.size());

Well that's it , it worked fine for me \o/

Answer 8

I don't know why I didn't find the best answer but its really simple.

recyclerView.smoothScrollToPosition(position);

No errors

Creates Animations

Answer 9

just call this method simply:

((LinearLayoutManager)recyclerView.getLayoutManager()).scrollToPositionWithOffset(yourItemPosition,0);

instead of:

recyclerView.scrollToPosition(yourItemPosition);

Answer 10

what i did to restore the scroll position after refreshing the RecyclerView on button clicked:

if (linearLayoutManager != null) {

    index = linearLayoutManager.findFirstVisibleItemPosition();
    View v = linearLayoutManager.getChildAt(0);
    top = (v == null) ? 0 : (v.getTop() - linearLayoutManager.getPaddingTop());
    Log.d("TAG", "visible position " + " " + index);
}

else{
    index = 0;
}

linearLayoutManager = new LinearLayoutManager(getApplicationContext());
linearLayoutManager.scrollToPositionWithOffset(index, top);

getting the offset of the first visible item from the top before creating the linearLayoutManager object and after instantiating it the scrollToPositionWithOffset of the LinearLayoutManager object was called.

Answer 11

scroll at particular position
and this helped me alot. by click listener you can get the position in your adapter

layoutmanager.scrollToPosition(int position);

Answer 12

If your LayoutManager is LinearLayoutManager you can use scrollToPositionWithOffset(position,0); on it and it will make your item the first visible item in the list. Otherwise, you can use smoothScrollToPosition on the RecyclerView directly.

I ended up using the below code.

 RecyclerView.LayoutManager layoutManager = mainList.getLayoutManager();
        if (layoutManager instanceof LinearLayoutManager) {
            // Scroll to item and make it the first visible item of the list.
            ((LinearLayoutManager) layoutManager).scrollToPositionWithOffset(position, 0);
        } else {
            mainList.smoothScrollToPosition(position);
        }

Answer 13

Introduction

None of the answers explain how to show last item(s) at the top. So, the answers work only for items that still have enough items above or below them to fill the remaining RecyclerView. For instance, if there are 59 elements and a 56-th element is selected it should be at the top as in the picture below:

So, let's see how to implement this in the next paragraph.

Solution

We could handle those cases by using linearLayoutManager.scrollToPositionWithOffset(pos, 0) and additional logic in the Adapter of RecyclerView - by adding a custom margin below the last item (if the last item is not visible then it means there's enough space fill the RecyclerView). The custom margin could be a difference between the root view height and the item height. So, your Adapter for RecyclerView would look as follows:

...
@Override
public void onBindViewHolder(ViewHolder holder, final int position) {
    ...

    int bottomHeight = 0;
    int itemHeight = holder.itemView.getMeasuredHeight();
    // if it's the last item then add a bottom margin that is enough to bring it to the top
    if (position == mDataSet.length - 1) {
        bottomHeight = Math.max(0, mRootView.getMeasuredHeight() - itemHeight);
    }
    RecyclerView.LayoutParams params = (RecyclerView.LayoutParams)holder.itemView.getLayoutParams();
    params.setMargins(0, 0, params.rightMargin, bottomHeight);
    holder.itemView.setLayoutParams(params);

    ...
} 
...

Answer 14

What i may add here is how to make it work together with DiffUtil and ListAdapter

You may note that calling recyclerView.scrollToPosition(pos) or (recyclerView.layoutManager as LinearLayoutManager).scrollToPositionWithOffset(pos, offset) wouldn't work if called straight after adapter.submitList. It is because the differ looks for changes in a background thread and then asynchronously notifies adapter about changes. On a SO i have seen several wrong answers with unnecessary delays & etc to solve this.

To handle the situation properly the submitList has a callback which is invoked when changes have applied.

So the proper kotlin implementations in this case are:

//memorise target item here and a scroll offset if needed
adapter.submitList(items) { 
    val pos = /* here you may find a new position of the item or just use just a static position. It depends on your case */
    recyclerView.scrollToPosition(pos) 
}
//or
adapter.submitList(items) { recyclerView.smoothScrollToPosition(pos) }
//or etc
adapter.submitList(items) { (recyclerView.layoutManager as LinearLayoutManager).scrollToPositionWithOffset(pos, offset) }

Answer 15

In my case my RecyclerView have a padding top like this

<android.support.v7.widget.RecyclerView
     ...
     android:paddingTop="100dp"
     android:clipToPadding="false"
/>

Then for scroll a item to top, I need to

recyclerViewLinearLayoutManager.scrollToPositionWithOffset(position, -yourRecyclerView.getPaddingTop());

Answer 16

please note that if scrollToPosition not work notice that your RecyclerView was inside a NestedScrollView; refer to this post

Answer 17

I use the code below to smooth-scroll an item (thisView) to the top.
It works also for GridLayoutManager with views of different heights:

View firstView = mRecyclerView.getChildAt(0);
int toY = firstView.getTop();
int firstPosition = mRecyclerView.getChildAdapterPosition(firstView);
View thisView = mRecyclerView.getChildAt(thisPosition - firstPosition);
int fromY = thisView.getTop();

mRecyclerView.smoothScrollBy(0, fromY - toY);

Seems to work good enough for a quick solution.