gistfile1.txt

public class CustomAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder>{
    //our items
    List<Generic> items = new Arraylist<>();
    //headers
    List<View> headers = new ArrayList<>();
    //footers
    List<View> footers = new ArrayList<>();

    public static final int TYPE_HEADER = 111;
    public static final int TYPE_FOOTER = 222;
    public static final int TYPE_ITEM = 333;

    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup viewGroup, int type) {
        //if our position is one of our items (this comes from getItemViewType(int position) below)
        if(type == TYPE_ITEM) {
            View view = LayoutInflater.from(viewGroup.getContext())
                    .inflate(R.layout.generic_layout, viewGroup, false);
            return new GenericViewHolder(view);
            //else we have a header/footer
        }else{
            //create a new framelayout, or inflate from a resource
            FrameLayout frameLayout = new FrameLayout(viewGroup.getContext());
            //make sure it fills the space
            frameLayout.setLayoutParams(new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT));
            return new HeaderFooterViewHolder(frameLayout);
        }
    }

    @Override
    public void onBindViewHolder(final RecyclerView.ViewHolder vh, int position) {
        //check what type of view our position is
        if(position < headers.size()){
            View v = headers.get(position);
            //add our view to a header view and display it
            prepareHeaderFooter((HeaderFooterViewHolder) vh, v);
        }else if(position >= headers.size() + items.size()){
            View v = footers.get(position-items.size()-headers.size());
            //add oru view to a footer view and display it
            prepareHeaderFooter((HeaderFooterViewHolder) vh, v);
        }else {
            //it's one of our items, display as required
            prepareGeneric((GenericViewHolder) vh, position-headers.size());
        }
    }

    @Override
    public int getItemCount() {
        //make sure the adapter knows to look for all our items, headers, and footers
        return headers.size() + items.size() + footers.size();
    }

    private void prepareHeaderFooter(HeaderFooterViewHolder vh, View view){
        //empty out our FrameLayout and replace with our header/footer
        vh.base.removeAllViews();
        vh.base.addView(view);
    }

    private void prepareGeneric(GenericViewHolder vh, int position){
        //do whatever we need to for our other type
        ...
    }

    @Override
    public int getItemViewType(int position) {
        //check what type our position is, based on the assumption that the order is headers > items > footers
        if(position < headers.size()){
            return TYPE_HEADER;
        }else if(position >= headers.size() + items.size()){
            return TYPE_FOOTER;
        }
        return TYPE_ITEM;
    }

    //add a header to the adapter
    public void addHeader(View header){
        if(!headers.contains(header)){
            headers.add(header);
            //animate
            notifyItemInserted(headers.size() - 1);
        }
    }

    //remove a header from the adapter
    public void removeHeader(View header){
        if(headers.contains(header)){
            //animate
            notifyItemRemoved(headers.indexOf(header));
            headers.remove(header);
            if(header.getParent() != null) {
                ((ViewGroup) header.getParent()).removeView(header);
            }
        }
    }

    //add a footer to the adapter
    public void addFooter(View footer){
        if(!footers.contains(footer)){
            footers.add(footer);
            //animate
            notifyItemInserted(headers.size()+items.size()+footers.size()-1);
        }
    }

    //remove a footer from the adapter
    public void removeFooter(View footer){
        if(footers.contains(footer)) {
            //animate
            notifyItemRemoved(headers.size()+items.size()+footers.indexOf(footer));
            footers.remove(footer);
            if(footer.getParent() != null) {
                ((ViewGroup) footer.getParent()).removeView(footer);
            }
        }
    }

    //our header/footer RecyclerView.ViewHolder is just a FrameLayout
    public static class HeaderFooterViewHolder extends RecyclerView.ViewHolder{
        FrameLayout base;
        public HeaderFooterViewHolder(View itemView) {
            super(itemView);
            this.base = (FrameLayout) itemView;
        }
    }
}

What is GenericViewHolder in that code??
I'm trying to implement your code in my project after implementing error shown like error resolve symbol 'GenericViewHolder'

@appcoderavi It is a class that used to hold your view basically.
It is a very useful pattern for performance improvements in your recyclerview for enhanced smoothness.
An example view holder class is bellow

public class ViewHolder extends RecyclerView.ViewHolder {
        public final View mView;
        public final TextView mainText;
        public final TextView secondaryText;
        public AnswerModel.Answer answer;

        public ViewHolder(View view) {
            super(view);
            mView = view;
            mainText = (TextView) view.findViewById(R.id.main_text);
            secondaryText = (TextView) view.findViewById(R.id.secondary_text);
        }
    }```

That is good solution

I have a Recycler view with Grid Layout. If I implement this code, would the header and footer too would be a grid item?