The is recyclerview adapter is use for concat with two adapter, by decorating

ConcatAdapter.java

package com.yjy.recyclerviewutils.adapter;

import android.support.annotation.NonNull;
import android.support.v7.widget.RecyclerView;
import android.util.SparseArray;
import android.view.ViewGroup;


public class ConcatAdapter extends RecyclerView.Adapter {
    private RecyclerView.Adapter mFirstAdapter;

    private RecyclerView.Adapter mLastAdapter;

    private SparseArray<RecyclerView.Adapter> mViewTypeAdapterMap = new SparseArray<>();

    public ConcatAdapter(RecyclerView.Adapter firstAdapter, RecyclerView.Adapter lastAdapter) {
        mFirstAdapter = firstAdapter;
        mLastAdapter = lastAdapter;
    }

    @Override
    public int getItemViewType(int position) {
        int itemViewType;

        if (position < mFirstAdapter.getItemCount()) {
            itemViewType = mFirstAdapter.getItemViewType(position);
            mViewTypeAdapterMap.put(itemViewType, mFirstAdapter);
        } else {
            itemViewType = mLastAdapter.getItemViewType(position);
            mViewTypeAdapterMap.put(itemViewType, mLastAdapter);
        }

        return itemViewType;
    }

    @NonNull
    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        return mViewTypeAdapterMap.get(viewType).onCreateViewHolder(parent, viewType);
    }

    @SuppressWarnings("unchecked")
    @Override
    public void onBindViewHolder(@NonNull RecyclerView.ViewHolder holder, int position) {
        if (position < mFirstAdapter.getItemCount()) {
            mFirstAdapter.onBindViewHolder(holder, position);
        } else {
            mLastAdapter.onBindViewHolder(holder, position);
        }
    }

    @Override
    public int getItemCount() {
        return mFirstAdapter.getItemCount() + mLastAdapter.getItemCount();
    }
}