How can I use getResources inside of onBindViewHolder()?

i can't use getResources inside onBindViewHolder()?

yes, you can. Use

   viewHolder.itemView.getResources();

getResources() is part View. No need to pass Context around

public void onBindViewHolder(ViewHolder viewHolder, int i) {
    Resources res = viewHolder.itemView.getContext().getResources();
    ...
}