public class Item {

    private String name;

    public Item(String n) {
        name = n;
    }
    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}

import androidx.recyclerview.widget.RecyclerView;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import com.codexpedia.list.viewholder.R;
import java.util.ArrayList;

public class ItemArrayAdapter extends RecyclerView.Adapter<ItemArrayAdapter.ViewHolder> {

    //All methods in this adapter are required for a bare minimum recyclerview adapter
    private int listItemLayout;
    private ArrayList<Item> itemList;
    // Constructor of the class
    public ItemArrayAdapter(int layoutId, ArrayList<Item> itemList) {
        listItemLayout = layoutId;
        this.itemList = itemList;
    }

    // get the size of the list
    @Override
    public int getItemCount() {
        return itemList == null ? 0 : itemList.size();
    }


    // specify the row layout file and click for each row
    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext()).inflate(listItemLayout, parent, false);
        ViewHolder myViewHolder = new ViewHolder(view);
        return myViewHolder;
    }

    // load data in each row element
    @Override
    public void onBindViewHolder(final ViewHolder holder, final int listPosition) {
        TextView item = holder.item;
        item.setText(itemList.get(listPosition).getName());
    }

    // Static inner class to initialize the views of rows
    static class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
        public TextView item;
        public ViewHolder(View itemView) {
            super(itemView);
            itemView.setOnClickListener(this);
            item = (TextView) itemView.findViewById(R.id.txtChords);
        }
        @Override
        public void onClick(View view) {
            Log.d("onclick", "onClick " + getLayoutPosition() + " " + item.getText());
        }
    }

import android.os.Bundle;
import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.DefaultItemAnimator;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

import com.codexpedia.list.viewholder.R;

import java.util.ArrayList;

public class MainActivity extends AppCompatActivity {

    RecyclerView recyclerView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // Initializing list view with the custom adapter
        ArrayList <Item> itemList = new ArrayList<Item>();

        ItemArrayAdapter itemArrayAdapter = new ItemArrayAdapter(R.layout.list_item, itemList);
        recyclerView = (RecyclerView) findViewById(R.id.item_list);
        recyclerView.setLayoutManager(new LinearLayoutManager(this));
        recyclerView.setItemAnimator(new DefaultItemAnimator());
        recyclerView.setAdapter(itemArrayAdapter);

        // Populating list items
        for(int i=0; i<100; i++) {
            itemList.add(new Item("Item " + i));
        }

    }

}

public class Entry implements DragColumn {
    private final String name;
    private int columnIndex;
    private final List<DragItem> itemList;

    public Entry(String name, int columnIndex, List<DragItem> items) {
        this.name = name;
        this.columnIndex = columnIndex;
        this.itemList = items;
    }

    public String getName() {
        return name;
    }

    public List<DragItem> getItemList() {
        return itemList;
    }

    @Override
    public int getColumnIndex() {
        return columnIndex;
    }

    @Override
    public void setColumnIndex(int columnIndexInHorizontalRecycleView) {
        //save to database here
    }
}

public class Item implements DragItem {
    private final String itemName;
    private int colIndex;
    private int itemIndex;

    public Item(String itemName, int colIndex, int itemIndex) {
        this.itemName = itemName;
        this.colIndex = colIndex;
        this.itemIndex = itemIndex;
    }

    public String getItemName() {
        return itemName;
    }

    @Override
    public int getColumnIndex() {
        return colIndex;
    }

    @Override
    public int getItemIndex() {
        return itemIndex;
    }

    @Override
    public void setColumnIndex(int columnIndexInHorizontalRecycleView) {
        //save to database here
    }

    @Override
    public void setItemIndex(int itemIndexInVerticalRecycleView) {
        //save to database here
    }
}

public class ColumnAdapter extends HorizontalAdapter<ColumnAdapter.ViewHolder>
public class ItemAdapter extends VerticalAdapter<ItemAdapter.ViewHolder>

public class MainActivity extends AppCompatActivity {

    DragBoardView dragBoardView;
    List<DragColumn> mData = new ArrayList<>();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        dragBoardView = findViewById(R.id.layout_main);
        mAdapter = new ColumnAdapter(this);
        mAdapter.setData(mData);
        dragBoardView.setHorizontalAdapter(mAdapter);
    }

}