在RecycleView适配器中实现多种ViewHolder类型 [英] Implement multiple ViewHolder types in RecycleView adapter

问题描述

如您所知，如果要在RecyclerView中实现多种类型，则应提供扩展RecyclerView.ViewHolder的多个CustomViewHolder.

As you know, if we want to implement multiple types in RecyclerView, we should provide multiple CustomViewHolder extending RecyclerView.ViewHolder.

例如，

class TextViewHolder extends RecyclerView.ViewHolder{
    TextView textView;
}

class ImageViewHolder extends RecyclerView.ViewHolder{
    ImageView imageView;
}

然后我们必须覆盖getItemViewType.然后在onCreateViewHolder中构造TextViewHolder或ImageViewHolder.

Then we have to override getItemViewType.And in onCreateViewHolder to construct TextViewHolder or ImageViewHolder.

@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    if (viewType == 0) {
        return new ImageViewHolder(mLayoutInflater.inflate(R.layout.item_image, parent, false));
    } else {
        return new TextViewHolder(mLayoutInflater.inflate(R.layout.item_text, parent, false));
    }
} 

以上代码是正常的，但是还有另一种方法.

Above code is normal but there is a another way.

我认为只有一个CustomViewHolder就足够了.

I think only one CustomViewHolder is enough.

 class MultipleViewHolder extends RecyclerView.ViewHolder{
    TextView textView;
    ImageView imageView;

    MultipleViewHolder(View itemView, int type){
       if(type == 0){
         textView = (TextView)itemView.findViewById(xx);
       }else{
         imageView = (ImageView)itemView.findViewById(xx);
       }
    }
 }

您在开发工作中使用哪种方式?

推荐答案

我个人喜欢 Yigit Boyar 建议的方法在这次演讲(快进31:07).不用从getItemViewType()返回常量int ，而是直接返回布局ID，它也是一个int并保证是唯一的:

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;
        }
    }

这将使您可以在onCreateViewHolder()中进行以下实现:

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;
    }

其中MyViewHolder是抽象类:

    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);
    }

并且FirstViewHolder在下面:

    public static class FirstViewHolder extends MyViewHolder {

        @BindView
        TextView title;

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

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

这将使onBindViewHolder()成为一线客:

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

因此，您将每个ViewHolder分开，其中bind(Item)仅负责执行特定于该ViewHolder的操作.

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

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