Implement multiple ViewHolder types in RecycleView adapter

Question

It\'s maybe a discussion not a question.

Normal way to implement multiple types

As you know, if we want to implement multiple types in RecyclerView

Answer 1

Personally I like approach suggested by Yigit Boyar in this talk (fast forward to 31:07). Instead of returning a constant int from getItemViewType(), return the layout id directly, which is also an int and is guaranteed to be unique:

    @Override
    public int getItemViewType(int position) {
        switch (position) {
            case 0:
                return R.layout.first;
            case 1:
                return R.layout.second;
            default:
                return R.layout.third;
        }
    }

This will allow you to have following implementation in onCreateViewHolder():

    @Override
    public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        LayoutInflater inflater = LayoutInflater.from(parent.getContext());
        View view = inflater.inflate(viewType, parent, false);

        MyViewHolder holder = null;
        switch (viewType) {
            case R.layout.first:
                holder = new FirstViewHolder(view);
                break;
            case R.layout.second:
                holder = new SecondViewHolder(view);
                break;
            case R.layout.third:
                holder = new ThirdViewHolder(view);
                break;
        }
        return holder;
    }

Where MyViewHolder is an abstract class:

    public static abstract class MyViewHolder extends RecyclerView.ViewHolder {

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

            // perform action specific to all viewholders, e.g.
            // ButterKnife.bind(this, itemView);
        }

        abstract void bind(Item item);
    }

And FirstViewHolder is following:

    public static class FirstViewHolder extends MyViewHolder {

        @BindView
        TextView title;

        public FirstViewHolder(View itemView) {
            super(itemView);
        }

        @Override
        void bind(Item item) {
            title.setText(item.getTitle());
        }
    }

This will make onBindViewHolder() to be one-liner:

    @Override
    public void onBindViewHolder(MyViewHolder holder, int position) {
        holder.bind(dataList.get(holder.getAdapterPosition()));
    }

Thus, you'd have each ViewHolder separated, where bind(Item) would be responsible to perform actions specific to that ViewHolder only.