android - 需要一个关于 RecyclerView.Adapter.notifyItemChanged(int position, Object payload) 的例子

Question

根据RecyclerView 文档关于方法notifyItemChanged(int position, Object payload)

Notify any registered observers that the item at position has changed with an optional payload object.

我不明白如何在此方法中使用第二个参数 payload。我搜索了很多关于“有效载荷”的文档，但一切都模棱两可。

所以，如果你知道这个方法，请给我一个清晰的例子。非常感谢。

Answer 1

如果您想更新不是所有持有人 View ，而只是部分更新，则此方法是您所需要的。

您关注的图像ViewHolder

public class ViewHolder extends RecyclerView.ViewHolder {
        public final TextView tvPlayer;
        public final TextView tvScore;

        public ViewHolder(View view) {
            super(view);
            tvPlayer = (TextView) view.findViewById(R.id.tv_player);
            tvScore = (TextView) view.findViewById(R.id.tv_score);
        }

    }

在代码中的某处调用适配器来更新 single TextView - tvScore

mRecyclerViewAdapter.notifyItemChanged(position, new Integer(4533));

[...]

onBindViewHolder(ViewHolder holder, int position, List payloads) 首先捕获回调。如果 payloads 不符合您的要求，您必须强制调用父类(super class) super.onBindViewHolder(holder,position, payloads); 触发 onBindViewHolder(ViewHolder holder, int position) 其他情况。

     // Update only part of ViewHolder that you are interested in
     // Invoked before onBindViewHolder(ViewHolder holder, int position)
        @Override
        public void onBindViewHolder(ViewHolder holder, int position, List<Object> payloads) {
            if(!payloads.isEmpty()) {
                if (payloads.get(0) instanceof Integer) {
                    holder.tvScore.setText(String.valueOf((Integer)payloads.get(0)))
                }
            }else {
                super.onBindViewHolder(holder,position, payloads);
            }
        }

    // Update ALL VIEW holder
    @Override
        public void onBindViewHolder(ViewHolder holder, int position) {
            MItem item = mList.get(position)
            // some update
        }