Recyclerview, I can't get item view with getChildAt(position). Null object reference

Question

I am using a recyclerView inside my navigation drawer and I am using this library Twoway-view to get click and selection support.

It works perfectly and I can change the color of the text and the icons without problems inside OnClick method for each position:

itemClickSupport.setOnItemClickListener(new ItemClickSupport.OnItemClickListener() {
        @Override
        public void onItemClick(RecyclerView parent, View view, int position, long id) {
            TypedValue typedValue = new TypedValue();
            MainActivity.this.getTheme().resolveAttribute(R.attr.colorAccent, typedValue, true);
            final int color = typedValue.data;

            //TODO Icon and text colors

            for (int i = 0; i < drawerTitles.length; i++){
                if (i == position){
                    ImageView imageViewDrawerIcon = (ImageView) recyclerViewDrawer.getChildAt(i).findViewById(R.id.imageViewDrawerIcon);
                    TextView textViewDrawerTitle = (TextView) recyclerViewDrawer.getChildAt(i).findViewById(R.id.textViewDrawerItemTitle);
                    imageViewDrawerIcon.setColorFilter(color);
                    if(Build.VERSION.SDK_INT > 15){
                        imageViewDrawerIcon.setImageAlpha(255);
                    }else{
                        imageViewDrawerIcon.setAlpha(255);
                    }
                    textViewDrawerTitle.setTextColor(color);
                    RelativeLayout relativeLayoutDrawerItem = (RelativeLayout) recyclerViewDrawer.getChildAt(i).findViewById(R.id.relativeLayoutDrawerItem);
                    relativeLayoutDrawerItem.setFocusableInTouchMode(true);
                }else{
                    ImageView imageViewDrawerIcon = (ImageView) recyclerViewDrawer.getChildAt(i).findViewById(R.id.imageViewDrawerIcon);
                    TextView textViewDrawerTitle = (TextView) recyclerViewDrawer.getChildAt(i).findViewById(R.id.textViewDrawerItemTitle);
                    imageViewDrawerIcon.setColorFilter(getResources().getColor(R.color.md_text));
                    if(Build.VERSION.SDK_INT > 15){
                        imageViewDrawerIcon.setImageAlpha(138);
                    }else{
                        imageViewDrawerIcon.setAlpha(138);
                    }
                    textViewDrawerTitle.setTextColor(getResources().getColor(R.color.md_text));
                    RelativeLayout relativeLayoutDrawerItem = (RelativeLayout) recyclerViewDrawer.getChildAt(i).findViewById(R.id.relativeLayoutDrawerItem);
                    relativeLayoutDrawerItem.setFocusableInTouchMode(false);
                }
            }

            //TODO Fragments (closedrawers before setfragment)
            final Handler handler = new Handler();
            handler.postDelayed(new Runnable() {
                @Override
                public void run() {
                    // Do something after some time

                }
            }, 250);
            mDrawerLayout.closeDrawers();
        }
    });

The problem is that I want to access to the first item like in that method, but before it (to set the first item selected, with different color, etc).

But I get a crash (null reference) when I try to get the first item outside OnClick method:

ImageView imageViewDrawerIcon = (ImageView) recyclerViewDrawer.getChildAt(0).findViewById(R.id.imageViewDrawerIcon);

All code:

// Setup RecyclerView inside drawer
    recyclerViewDrawer = (RecyclerView) findViewById(R.id.recyclerViewDrawer);
    recyclerViewDrawer.setHasFixedSize(true);
    recyclerViewDrawer.setLayoutManager(new LinearLayoutManager(MainActivity.this));

    ArrayList<DrawerItem> drawerItems = new ArrayList<>();
    final String[] drawerTitles = getResources().getStringArray(R.array.drawer);
    final TypedArray drawerIcons = getResources().obtainTypedArray(R.array.drawerIcons);
    for (int i = 0; i < drawerTitles.length; i++) {
        drawerItems.add(new DrawerItem(drawerTitles[i], drawerIcons.getDrawable(i)));
    }
    drawerIcons.recycle();
    adapterDrawer = new DrawerAdapter(drawerItems);
    recyclerViewDrawer.setAdapter(adapterDrawer);

    // Here is the problem
    ImageView imageViewDrawerIcon2 = (ImageView) recyclerViewDrawer.getChildAt(0).findViewById(R.id.imageViewDrawerIcon);

    // RecyclerView item listener.
    ItemClickSupport itemClickSupport = ItemClickSupport.addTo(recyclerViewDrawer);
    itemClickSupport.setOnItemClickListener(new ItemClickSupport.OnItemClickListener() {
        @Override
        public void onItemClick(RecyclerView parent, View view, int position, long id) {
            TypedValue typedValue = new TypedValue();
            MainActivity.this.getTheme().resolveAttribute(R.attr.colorAccent, typedValue, true);
            final int color = typedValue.data;

            //TODO Icon and text colors

            for (int i = 0; i < drawerTitles.length; i++){
                if (i == position){
                    ImageView imageViewDrawerIcon = (ImageView) recyclerViewDrawer.getChildAt(i).findViewById(R.id.imageViewDrawerIcon);
                    TextView textViewDrawerTitle = (TextView) recyclerViewDrawer.getChildAt(i).findViewById(R.id.textViewDrawerItemTitle);
                    imageViewDrawerIcon.setColorFilter(color);
                    if(Build.VERSION.SDK_INT > 15){
                        imageViewDrawerIcon.setImageAlpha(255);
                    }else{
                        imageViewDrawerIcon.setAlpha(255);
                    }
                    textViewDrawerTitle.setTextColor(color);
                    RelativeLayout relativeLayoutDrawerItem = (RelativeLayout) recyclerViewDrawer.getChildAt(i).findViewById(R.id.relativeLayoutDrawerItem);
                    relativeLayoutDrawerItem.setFocusableInTouchMode(true);
                }else{
                    ImageView imageViewDrawerIcon = (ImageView) recyclerViewDrawer.getChildAt(i).findViewById(R.id.imageViewDrawerIcon);
                    TextView textViewDrawerTitle = (TextView) recyclerViewDrawer.getChildAt(i).findViewById(R.id.textViewDrawerItemTitle);
                    imageViewDrawerIcon.setColorFilter(getResources().getColor(R.color.md_text));
                    if(Build.VERSION.SDK_INT > 15){
                        imageViewDrawerIcon.setImageAlpha(138);
                    }else{
                        imageViewDrawerIcon.setAlpha(138);
                    }
                    textViewDrawerTitle.setTextColor(getResources().getColor(R.color.md_text));
                    RelativeLayout relativeLayoutDrawerItem = (RelativeLayout) recyclerViewDrawer.getChildAt(i).findViewById(R.id.relativeLayoutDrawerItem);
                    relativeLayoutDrawerItem.setFocusableInTouchMode(false);
                }
            }

            //TODO Fragments (closedrawers before setfragment)
            final Handler handler = new Handler();
            handler.postDelayed(new Runnable() {
                @Override
                public void run() {
                    // Do something after some time

                }
            }, 250);
            mDrawerLayout.closeDrawers();
        }
    });

Possible duplicate of [RecyclerView - Get view at particular position](https://stackoverflow.com/questions/33784369/recyclerview-get-view-at-particular-position) — Kaibo, Nov 01 '19 at 12:58

score 20 · Answer 1 · answered Apr 12 '16 at 10:16

20

In my case it,is work like a charm

View viewItem = recycleView.getLayoutManager().findViewByPosition(position);
    View icon = viewItem.findViewById(R.id.view);

answered Apr 12 '16 at 10:16

Dmitriy

346
4
8

Gives warning "Before Android 4.1, method int android.support.v7.widget.ListViewCompat.lookForSelectablePosition(int, boolean) would have incorrectly overridden the package-private method in android.widget.ListView" – Patriotic Jun 03 '18 at 18:01
4

it returns `null` – user25 Mar 17 '19 at 22:21
Seems it works only if item is visible right now, useless. Even if I call `layoutManager.scrollToPosition(position)` before calling `findViewByPosition(position)` it still doesn't work – user25 Mar 17 '19 at 22:22

score 9 · Accepted Answer · edited May 23 '17 at 12:34

I solved finally with this (source):

recyclerViewDrawer.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
        @Override
        public void onGlobalLayout() {
            ImageView imageViewDrawerIcon = (ImageView) recyclerViewDrawer.getChildAt(0).findViewById(R.id.imageViewDrawerIcon);
            TextView textViewDrawerTitle = (TextView) recyclerViewDrawer.getChildAt(0).findViewById(R.id.textViewDrawerItemTitle);
            imageViewDrawerIcon.setColorFilter(color);
            if (Build.VERSION.SDK_INT > 15) {
                imageViewDrawerIcon.setImageAlpha(255);
            } else {
                imageViewDrawerIcon.setAlpha(255);
            }
            textViewDrawerTitle.setTextColor(color);
            RelativeLayout relativeLayoutDrawerItem = (RelativeLayout) recyclerViewDrawer.getChildAt(0).findViewById(R.id.relativeLayoutDrawerItem);
            relativeLayoutDrawerItem.setFocusableInTouchMode(true);
            // unregister listener (this is important)
            recyclerViewDrawer.getViewTreeObserver().removeGlobalOnLayoutListener(this);
        }
    });

By the way, if someone have a better solution I would like to know it.

We're still getting some instances of `getChildViiew(0)` being null with this approach. I personally can't reproduce it. Using `setAdapter` triggers the child view inflation so ideally there would be a callback that is called when the child view is inflated and added to the RecyclerView — ono, Jul 25 '16 at 18:18

score 8 · Answer 3 · answered May 04 '17 at 14:35

8

This worked for me.

recyclerView.post(new Runnable() {
  @Override
  public void run() {
    View viewItem = recycleView.getLayoutManager().findViewByPosition(position);
    View icon = viewItem.findViewById(R.id.view);
  }
});

answered May 04 '17 at 14:35

Hermandroid

2,120
4
29
35

Nice, this worked perfectly for getting the displayed children and viewholders using `getChildAt()` and `getChildViewHolder()` – Peterdk Apr 10 '19 at 11:42
Of note is that you can't manipulate many UI elements with this, since you're working from a different thread. You'll have to set up inter-thread communication. – Kilves May 08 '19 at 12:09

score 5 · Answer 4 · answered Feb 10 '16 at 07:44

5

I would use findViewHolderForAdapterPosition() or findViewByPosition() instead to find the root view at that index. The way you ensure the data is loaded is up to you, however.

answered Feb 10 '16 at 07:44

AllDayAmazing

2,383
1
24
25

score 1 · Answer 5 · answered Oct 21 '19 at 13:37

findViewByPosition is a method of LayoutManager, which works with all LayoutManagers.

So you can use recycleView.getLayoutManager() and findViewByPosition(pos).

Also recyclerView.findViewHolderForAdapterPosition(pos) works too.

For more information, look at this RecyclerView - Get view at particular position

score 0 · Answer 6 · answered Jul 20 '23 at 18:23

0

You can get ItemView from recyclerView's holder using below code:

val holder = yourRecyclerView.findViewHolderForAdapterPosition(position)
if (holder != null) {
  val rootView = holder.itemView
  //do your code here
}

answered Jul 20 '23 at 18:23

Anant Shah

3,744
1
35
48

Recyclerview, I can't get item view with getChildAt(position). Null object reference

6 Answers6