java.lang.IllegalStateException: ViewHolder views must not be attached when created.
这说明onCreateViewHolder 方法写错了
这句话的意思是，viewHolder不予许在创建的时候添加到parent里，所以如果在onCreateViewHolder方法里使用：

View view = inflater.inflate(R.layout.item_view, parent, true);
或者
View view = inflater.inflate(R.layout.item_view, parent);

就会报错:

ViewHolder views must not be attached when created. Ensure that you are not passing ‘true’ to the attachToRoot parameter of LayoutInflate

只要改成：

// View view = inflater.inflate(R.layout.item_view, null); 或者
// View view = inflater.inflate(R.layout.item_view, parent, false);
View rootView = LayoutInflater.from(CheckInActivity.this).inflate( R.layout.layout_check_in_week, parent,false);