RecyclerView index=-1 快速滚动到底部时

Question

I have created a RecyclerView to display items and everything shows and works fine except to one scenario: when I scroll fast to the bottom of the RecyclerView .

If I do so, I get the following error:

java.lang.ArrayIndexOutOfBoundsException: length=15; index=-1

It directs me to this part of my code (specifically to checkIfBorrowed.get( getAdapterPosition() ) ):

public class itemtestAdapter extends RecyclerView.Adapter<itemtestAdapter.testViewHolder> {

    private List<Discoveritems> items;
    private List<Boolean> checkIftested;

    interface OnItemCheckListener {
        void onItemCheck(Discoveritems items);
        void onItemUncheck(Discoveritems items);
    }

    @NonNull
    private OnItemCheckListener onItemCheckListener;

    public itemtestAdapter(List<Discoveritems> items, List<Boolean> checkIftested, @NonNull OnItemCheckListener onItemCheckListener) {
        this.items = items;
        this.onItemCheckListener = onItemCheckListener;
        this.checkIftested = checkIftested;
    }

    @Override
    public testViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view;
        view = LayoutInflater.from(parent.getContext()).inflate( R.layout.item_item_test_list, parent, false );
        return new testViewHolder(view);
    }

    @Override
    public void onBindViewHolder(testViewHolder holder, int position) {
        holder.bind(items.get(position));

        final Discoveritems currentItem = items.get(position);

        holder.setOnClickListener( v -> {
            holder.Cb_test.setChecked(
                    !holder.Cb_test.isChecked());
            if (holder.Cb_test.isChecked()) {
                onItemCheckListener.onItemCheck(currentItem);
            } else {
                onItemCheckListener.onItemUncheck(currentItem);
            }
        } );

    }

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

    class testViewHolder extends RecyclerView.ViewHolder {
        ImageView Iv_test,itemPic;
        TextView itemName;
        CheckBox Cb_test;
        Discoveritems items;

        public testViewHolder(View itemView) {
            super(itemView);

            Iv_testitemPic = itemView.findViewById(R.id.iv_itemCover);
            Tv_testitemName = itemView.findViewById( R.id.tv_testeditemName);
            Cb_test = itemView.findViewById( R.id.cb_testitem );
            Cb_test.setClickable( false );

        }

        public void setOnClickListener(View.OnClickListener onClickListener) {
            itemView.setOnClickListener(onClickListener);
        }

        public void bind(Discoveritems items) {

            this.items = items;

            String itemID = items.getitemID();
            MyitemClient client = new MyitemClient();
            client.getitems(itemID, new JsonHttpResponseHandler(){
                @Override
                public void onSuccess(int statusCode, Header[] headers, JSONObject response){
                    if(response!=null){
                        final Myitem items = Myitem.fromJson(response);

                        if (checkIftested.get( getAdapterPosition() )){
                            itemView.setEnabled(false);
                            Tv_itemName.setText("my" + items.getTitle());
                        } else {
                            Tv_itemName.setText( items.getTitle() );
                        }
                    }
                }

            });
            
        }
    }

}

Thing is that inside bind I can't figure out how to get the position of the item without using getAdapterPosition and I also cant understand why it only happens when I scroll fast.

Also it is weird that it says length = 15 while checkIfBorowed's size is 12 only. Thank you

Answer 1

Change holder.bind(items.get(position)); to holder.bind(items.get(position), position); and then change viewholders bind method to accept the new position argument ie bind(Discoveritems items, int position) and use position instead of getAdapterPosition() .

The issue is you are not using the position the adapter gave your viewholder which can change when views are recycled and thus they dont macth. Please see here for more https://stackoverflow.com/a/38970513/1133011