[android] How to update RecyclerView Adapter Data?



Answers

This is what worked for me:

recyclerView.setAdapter(new RecyclerViewAdapter(newList));
recyclerView.invalidate();

After creating a new adapter that contains the updated list (in my case it was a database converted into an ArrayList) and setting that as adapter, I tried recyclerView.invalidate() and it worked.

Question

For 4 days I can't figure out what exactly is the issue with updating RecyclerView's Adapter.

After I get a new List of products, I tried to:

  1. Update the ArrayList from the fragment where recyclerView is created, set new data to adapter, then call adapter.notifyDataSetChanged() ; it did not work.

  2. Create a new adapter, as others did, and it worked for them, but no change for me: recyclerView.setAdapter(new RecyclerViewAdapter(newArrayList))

  3. Create a method in Adapter which updates the data as follows:

    public void updateData(ArrayList<ViewModel> viewModels) {
       items.clear();
       items.addAll(viewModels);
       notifyDataSetChanged();
    }
    

    Then I call this method whenever I want to update the data list; it did not work.

  4. To check if I can modify the recyclerView in any way, and I tried to remove at least an item:

     public void removeItem(int position) {
        items.remove(position);
        notifyItemRemoved(position);
    }
    

    Everything remained as it was.

Here is my Adapter:

public class RecyclerViewAdapter extends RecyclerView.Adapter<RecyclerViewAdapter.ViewHolder> implements View.OnClickListener {

    private ArrayList<ViewModel> items;
    private OnItemClickListener onItemClickListener;

    public RecyclerViewAdapter(ArrayList<ViewModel> items) {
        this.items = items;
    }


    public void setOnItemClickListener(OnItemClickListener onItemClickListener) {
        this.onItemClickListener = onItemClickListener;
    }

    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_recycler, parent, false);
        v.setOnClickListener(this);
        return new ViewHolder(v);
    }

    public void updateData(ArrayList<ViewModel> viewModels) {
        items.clear();
        items.addAll(viewModels);
        notifyDataSetChanged();
    }
    public void addItem(int position, ViewModel viewModel) {
        items.add(position, viewModel);
        notifyItemInserted(position);
    }

    public void removeItem(int position) {
        items.remove(position);
        notifyItemRemoved(position);
    }



    @Override
    public void onBindViewHolder(ViewHolder holder, int position) {
        ViewModel item = items.get(position);
        holder.title.setText(item.getTitle());
        Picasso.with(holder.image.getContext()).load(item.getImage()).into(holder.image);
        holder.price.setText(item.getPrice());
        holder.credit.setText(item.getCredit());
        holder.description.setText(item.getDescription());

        holder.itemView.setTag(item);
    }

    @Override
    public int getItemCount() {
        return items.size();
    }

    @Override
    public void onClick(final View v) {
        // Give some time to the ripple to finish the effect
        if (onItemClickListener != null) {
            new Handler().postDelayed(new Runnable() {
                @Override
                public void run() {
                    onItemClickListener.onItemClick(v, (ViewModel) v.getTag());
                }
            }, 0);
        }
    }

    protected static class ViewHolder extends RecyclerView.ViewHolder {
        public ImageView image;
        public TextView price, credit, title, description;

        public ViewHolder(View itemView) {
            super(itemView);
            image = (ImageView) itemView.findViewById(R.id.image);
            price = (TextView) itemView.findViewById(R.id.price);
            credit = (TextView) itemView.findViewById(R.id.credit);
            title = (TextView) itemView.findViewById(R.id.title);
            description = (TextView) itemView.findViewById(R.id.description);
        }
    }

    public interface OnItemClickListener {

        void onItemClick(View view, ViewModel viewModel);

    }
}

And I initiate RecyclerView as follows:

recyclerView = (RecyclerView) view.findViewById(R.id.recycler);
recyclerView.setLayoutManager(new GridLayoutManager(getActivity(), 5));
adapter = new RecyclerViewAdapter(items);
adapter.setOnItemClickListener(this);
recyclerView.setAdapter(adapter);

So, how do I actually update adapter data in order to display newly received items?


Update: the issue was that the layout where gridView was looked as follows:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:tag="catalog_fragment"
    android:layout_height="match_parent">

    <FrameLayout
        android:orientation="vertical"
        android:layout_width="match_parent"
        android:layout_height="match_parent">

        <android.support.v7.widget.RecyclerView
            android:id="@+id/recycler"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:clipToPadding="false"/>

        <ImageButton
            android:id="@+id/fab"
            android:layout_gravity="top|end"
            style="@style/FabStyle"/>

    </FrameLayout>
</LinearLayout>

Then I just removed LinearLayout and made FrameLayout as parent layout.




I found out that a really simple way to reload the RecyclerView is to just call

recyclerView.removeAllViews();

This will first remove all content of the RecyclerView and then add it again with the updated values.




If nothing mentioned in the above comments is working for you. It might mean the problem lies somewhere else.

One place I found the solution was in the way I was setting the list to the adapter. In my activity the list was a instance variable and I was changing it directly when any data changed. Due to it being a reference variable there was something weird going on. So I changed the reference variable to a local one and used another variable to update data and then pass to addAll() function mentioned in above answers.




you have 2 options to do this: refresh UI from the adapter:

mAdapter.notifyDataSetChanged();

or refresh it from recyclerView itself:

recyclerView.invalidate();



The best and the coolest way to add new data to the present data is

 ArrayList<String> newItems = new ArrayList<String>();
 newItems = getList();
 int oldListItemscount = alcontainerDetails.size();
 alcontainerDetails.addAll(newItems);           
 recyclerview.getAdapter().notifyItemChanged(oldListItemscount+1, al_containerDetails);



Another option is to use diffutil . It will compare the original list against the new list and use the new list as the update if there is a change.

Basically, we can use DiffUtil to compare the old data vs new data and let it call notifyItemRangeRemoved, and notifyItemRangeChanged and notifyItemRangeInserted on your behalf.

A quick example of using diffUtil instead of notifyDataSetChanged:

DiffResult diffResult = DiffUtil
                .calculateDiff(new MyDiffUtilCB(getItems(), items));

  //any clear up on memory here and then

        diffResult.dispatchUpdatesTo(this);

I do the calclateDiff work off the main thread in case it's a big list.




Links