Ayuda - ¿Como actualizar items de RecyclerView cuando se elimina un registro, actualiza o agrega?

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
                xmlns:tools="http://schemas.android.com/tools"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                tools:context=".MainActivity">

    <Button
        android:id="@+id/bt_eliminar"
        android:text="Eliminar"
        android:layout_width="match_parent"
        android:layout_height="40dp"/>

    <LinearLayout
        android:orientation="horizontal"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_marginTop="50dp">

        <FrameLayout
            android:id="@+id/content"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="1"/>

        <FrameLayout
            android:id="@+id/detail"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="1"/>
    </LinearLayout>

</RelativeLayout>

Datos.java

package com.a01luisrene.comunicacionfragments;


public class Datos {
    private String mTitle;
    private String mSubTitle;

    Datos(String title, String subTitle){
        mTitle = title;
        mSubTitle = subTitle;
    }

    public String getmTitle() {
        return mTitle;
    }

    public void setmTitle(String mTitle) {
        this.mTitle = mTitle;
    }

    public String getmSubTitle() {
        return mSubTitle;
    }

    public void setmSubTitle(String mSubTitle) {
        this.mSubTitle = mSubTitle;
    }
}

datos_item.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              android:layout_width="match_parent"
              android:layout_height="wrap_content"
              android:background="?attr/selectableItemBackground"
              android:layout_marginBottom="8dp"
              android:orientation="vertical">

    <TextView
        android:id="@+id/vertical_list_item_title"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_margin="5dp"
        android:textSize="20sp" />

    <TextView
        android:id="@+id/vertical_list_item_subtitle"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_margin="5dp" />

</LinearLayout>

fragment_a.xml

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
             xmlns:tools="http://schemas.android.com/tools"
             android:layout_width="match_parent"
             android:layout_height="match_parent"
             tools:context="com.a01luisrene.comunicacionfragments.FragmentA">

    <android.support.v7.widget.RecyclerView
        android:id="@+id/fragment_recycler_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

</FrameLayout>

fragment_b.xml

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
             xmlns:tools="http://schemas.android.com/tools"
             android:layout_width="match_parent"
             android:layout_height="match_parent"
             tools:context="com.a01luisrene.comunicacionfragments.FragmentB">

    <Button
        android:id="@+id/bt_agregar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Agregar"/>

</FrameLayout>

FragmentA.java

package com.a01luisrene.comunicacionfragments;


import android.content.DialogInterface;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v7.app.AlertDialog;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

import java.util.ArrayList;


public class FragmentA extends Fragment implements RecyclerViewAdapter.MyClickListener {

    private RecyclerView mRecyclerView;
    private RecyclerViewAdapter mAdapter;


    public FragmentA() {
        // Required empty public constructor
    }

    public static FragmentA newInstance() {
        return new FragmentA();
    }


    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        if (getArguments() != null) {

        }
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment

        // Inflate the layout for this fragment
        View view = inflater.inflate(R.layout.fragment_a, container, false);

        mRecyclerView = (RecyclerView) view.findViewById(R.id.fragment_recycler_view);
        mRecyclerView.setHasFixedSize(true);

        mRecyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));

        mAdapter = new RecyclerViewAdapter(getDataSet());

        mRecyclerView.setAdapter(mAdapter);
        mAdapter.setOnItemClickListener(this);

        return view;

    }

    private ArrayList<Datos> getDataSet() {
        ArrayList results = new ArrayList<>();
        for (int index = 0; index < 5; index++) {
            Datos obj = new Datos("Some Primary Text " + index,
                    "Secondary " + index);
            results.add(index, obj);
        }
        return results;
    }

    @Override
    public void onItemClick(final int position, View v) {
        new AlertDialog.Builder(getActivity())
                .setTitle("Eliminar item")
                .setMessage("¿stas seguro de eliminar item?")
                .setPositiveButton(android.R.string.yes, new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialog, int which) {
                        // continue with delete
                        mAdapter.deleteItem(position);
                        Log.v("Posicion", String.valueOf(position));
                    }
                })
                .setNegativeButton(android.R.string.no, new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialog, int which) {
                        // do nothing
                    }
                })
                .setIcon(android.R.drawable.ic_dialog_alert)
                .show();
    }

        public void addItem() {
            new AlertDialog.Builder(getActivity())
                    .setTitle("Agregar Item")
                    .setMessage("¿Estas seguro de agregar el nuevo item?")
                    .setPositiveButton(android.R.string.yes, new DialogInterface.OnClickListener() {
                        public void onClick(DialogInterface dialog, int which) {
                            // continue with delete
                            actionAdd();
                        }
                    })
                    .setNegativeButton(android.R.string.no, new DialogInterface.OnClickListener() {
                        public void onClick(DialogInterface dialog, int which) {
                            // do nothing
                        }
                    })
                    .setIcon(android.R.drawable.ic_dialog_alert)
                    .show();
        }

        public void eliminar(final int position){
            mAdapter.deleteItem(position);
            Log.v("Posicion", String.valueOf(position));
        }

        public void actionAdd() {

            Datos object = new Datos("Some Primary Text " + mAdapter.getItemCount(),
                    "Secondary " + mAdapter.getItemCount());
            mAdapter.addItem(object, mAdapter.getItemCount());

            mRecyclerView.scrollToPosition(mAdapter.getItemCount() - 1);

        }


}

FragmentB.java

package com.a01luisrene.comunicacionfragments;


import android.content.Context;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;


public class FragmentB extends Fragment implements View.OnClickListener {

    Button btAgregar;
    FragmentA mFragment;

    // Interfaz Actualizar
    public interface Actualizar{

        // Método de la interfaz
        public void actualizarItem();
    }

    // Objeto de la interfaz actualizar, con este objeto llamaremos el
    // método de la interfaz
    Actualizar actualizar;

    public FragmentB() {
        // Required empty public constructor
    }

    // Instancia
    public static FragmentB newInstance(){
        return new FragmentB();
    }



    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        if (getArguments() != null) {

        }
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        View v = inflater.inflate(R.layout.fragment_b, container, false);

        btAgregar = (Button) v.findViewById(R.id.bt_agregar);
        btAgregar.setOnClickListener(this);
        return v;
    }

    @Override
    public void onClick(View v) {
        switch (v.getId()){
            case R.id.bt_agregar:
                // Se llama el método de la interfaz Actualizar. Al implementar la
                // interfaz Actualizar en la actividad, este método se sobrescribirá
                // y al presionar el botón guardar de este fragment este método se
                // ejecutara en la actividad.
                actualizar.actualizarItem();
                break;

        }
    }

    @Override
    public void onAttach(Context context) {
        super.onAttach(context);

        // Aquí nos aseguramos de que en la actividad se haya implementado la interfaz,
        // si el programador no la implementado se lanza el mensaje de error.
        try {
            actualizar = (Actualizar) context;
        } catch (ClassCastException e) {
            throw new ClassCastException(context.toString() + " Debe implementar la interfaz Actualizar en su Activity");
        }
    }

}

RecyclerViewAdapter.java

package com.a01luisrene.comunicacionfragments;

import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

import java.util.ArrayList;

public class RecyclerViewAdapter extends RecyclerView.Adapter<RecyclerViewAdapter
        .DataObjectHolder> {

    private ArrayList<Datos> mDataset;

    private static RecyclerViewAdapter.MyClickListener sClickListener;

    static class DataObjectHolder extends RecyclerView.ViewHolder
            implements View
            .OnClickListener {
        TextView mLabel;
        TextView mDateTime;

        DataObjectHolder(View itemView) {
            super(itemView);
            mLabel = (TextView) itemView.findViewById(R.id.vertical_list_item_title);
            mDateTime = (TextView) itemView.findViewById(R.id.vertical_list_item_subtitle);
            itemView.setOnClickListener(this);
        }

        @Override
        public void onClick(View v) {
            sClickListener.onItemClick(getAdapterPosition(), v);
        }
    }

    void setOnItemClickListener(RecyclerViewAdapter.MyClickListener myClickListener) {
        this.sClickListener = myClickListener;
    }

    RecyclerViewAdapter(ArrayList<Datos> myDataset) {
        mDataset = myDataset;
    }

    @Override
    public RecyclerViewAdapter.DataObjectHolder onCreateViewHolder(ViewGroup parent,
                                                                           int viewType) {
        View view = LayoutInflater.from(parent.getContext())
                .inflate(R.layout.datos_item, parent, false);

        DataObjectHolder dataObjectHolder = new DataObjectHolder(view);

        return dataObjectHolder;
    }

    @Override
    public void onBindViewHolder(RecyclerViewAdapter.DataObjectHolder holder, int position) {
        holder.mLabel.setText(mDataset.get(position).getmTitle());
        holder.mDateTime.setText(mDataset.get(position).getmSubTitle());
    }

    void addItem(Datos dataObj, int index) {
        mDataset.add(dataObj);
        notifyItemInserted(index);
    }

    void deleteItem(int index) {
        mDataset.remove(index);
        notifyItemRemoved(index);
    }

    @Override
    public int getItemCount() {
        return mDataset.size();
    }

    interface MyClickListener {
        void onItemClick(int position, View v);
    }

}

Hola Luis