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

User · Answer

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

User · Answer

Scroll item pos  linearLayoutManager scrollToPositionWithOffset pos  0

User · Answer

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

User · Answer

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

User · Answer

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  amp  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

User · Answer

just call this method simply     LinearLayoutManager recyclerView getLayoutManager    scrollToPositionWithOffset yourItemPosition 0     instead of   recyclerView scrollToPosition yourItemPosition

User · Answer

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

User · Answer

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

User · Answer

In my case my RecyclerView have a padding top like this    lt android support v7 widget RecyclerView               android paddingTop  100dp       android clipToPadding  false    gt    Then for scroll a item to top  I need to  recyclerViewLinearLayoutManager scrollToPositionWithOffset position  -yourRecyclerView getPaddingTop

User · Answer

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

User · Answer

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

User · Answer

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

User · Answer

I don t know why I didn t find the best answer but its really simple   recyclerView smoothScrollToPosition position     No errors  Creates Animations

User · Answer

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

User · Answer

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

User · Answer

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    gt Step 1  You need to declare SmoothScroller  RecyclerView SmoothScroller smoothScroller   new                 LinearSmoothScroller this getApplicationContext                           Override                     protected int getVerticalSnapPreference                             return LinearSmoothScroller SNAP TO START                                              gt step 2  You need to add this code any event you want to perform scroll to specific position    gt First you need to set target position to SmoothScroller  smoothScroller setTargetPosition position      gt Then you need to set SmoothScroller to LayoutManager  mRecyclerView getLayoutManager   startSmoothScroll smoothScroller

[android] Scroll RecyclerView to show selected item on top

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