setWhich(int which)；
然後，初始化adapter，設定預設值；

adapter.setItemClick(new OnRecyItemClick() {
    @Override
public void onItemClick(View v, int position) {

   adapter.setWhich(position);
   adapter.notifyDataSetChanged();
}

RecyclerView.LayoutManager manager = rcl_door_list.getLayoutManager();
for (int 
 
i = 0; i < manager.getChildCount(); i++) {
    if (i != position) {
        View view = manager.getChildAt(i);
        if (view != null) {
            view.findViewById(R.id.rl_content).setBackground(getResources().getDrawable(R.drawable.item_border_door));
((TextView) view.findViewById(R.id.item_door_name
 
)).setTextColor(getResources().getColor(R.color.house_cccccc));
}
    }
}