拖放RecyclerView

Question

基本上，我试图拖放Recyclerview及其作品。

import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.support.v7.widget.RecyclerView; 
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import android.widget.Toast;
import java.io.IOException;
import java.util.ArrayList; 
import java.util.Collections;
import java.util.List;
import java.util.Set;

public class Ta extends RecyclerView.Adapter<RecyclerView.ViewHolder> 
implements ItemTouchHelpAdapter {
public ArrayList<String> cry;
private Context context;
private final OnStartDragListener mDragStartListener;
public static ArrayList<String> rk=new ArrayList<String>();

String msg;

public Ta(ArrayList<String> tc, Context context, OnStartDragListener dragListner,String ms) {
    this.msg=ms;
    this.context = context;
    mDragStartListener = dragListner;
       this.cry = tc;
}

@Override
public Vh onCreateViewHolder(ViewGroup parent, int viewType) {
    LayoutInflater layoutInflater = LayoutInflater.from(parent.getContext());
    View view = layoutInflater.inflate(R.layout.la, parent, false);
    return new Vh(view);
}

@Override
public void onBindViewHolder(final RecyclerView.ViewHolder holder, final int position) {

    String title = cry.get(position);
    final Vh holder2 = (Vh) holder;
    holder2.txt.setText(title);
    ((Vh) holder).txt.setOnLongClickListener(new View.OnLongClickListener() {
        @Override
        public boolean onLongClick(View v) {
            if (v.isLongClickable()) {
                mDragStartListener.onStartDrag(holder2);
            }
            return false;
        }
    });
    ((Vh)holder).txt.setOnClickListener(new View.OnClickListener(){

        @Override
        public void onClick(View v) {
            String w = cry.get(position);
            Toast.makeText(context, "Loading..", Toast.LENGTH_SHORT).show();
            Intent inw = new Intent(context, WebActivity.class);
            inw.putExtra("Webs", w);
            context.startActivity(inw);
        }
        });
}

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

@Override
public boolean onItemMove(int fromPosition, int toPosition) {
    Collections.swap(cry, fromPosition, toPosition);
    String item=cry.remove(fromPosition);
    cry.add(toPosition,item);
    notifyItemMoved(fromPosition,toPosition);
//here i'm trying to store updated value of cry arraylist to rk
    rk.clear();
    for (int ik=0;ik<cry.size();ik++)
    {
        rk.add(cry.get(ik));
    }
    Toast.makeText(context, rk.get(2), Toast.LENGTH_SHORT).show();
    return true;

}

@Override
public void onItemDismiss(int position) {
    cry.remove(position);
    notifyItemRemoved(position);
}

public class Vh extends RecyclerView.ViewHolder implements View.OnClickListener, View.OnLongClickListener, ItemTouchHelperViewHolder {
    TextView txt;
    private ItemClickListener itemClickListener;
    public Vh(View itemView) {
        super(itemView);
        txt = (TextView) itemView.findViewById(R.id.txt);
        itemView.setOnClickListener(this);
        itemView.setOnLongClickListener(this);

    }

    public void setItemClickListener(ItemClickListener itemClickListener) {
        this.itemClickListener = itemClickListener;
    }

    @Override
    public void onClick(View v) {
        itemClickListener.onClick(v, getAdapterPosition(), false);
    }

    @Override
    public boolean onLongClick(View v) {
        itemClickListener.onClick(v, getAdapterPosition(), true);
        return false;
    }

    @Override
    public void onItemSelected(View v) {
        v.setBackgroundColor(0xFFE0E0E0);

    }

    @Override
    public void onItemClear(View v) {

        v.setBackgroundColor(0xFF000000);
    }
}
}

当我尝试拖放列表时，它可以工作，我可以执行拖放但问题是当我尝试将更新的arraylist分配给另一个arraylist rk时，它总是存储未更改的arraylist。我想在拖放后更新arraylist并在另一个类中使用它。帮我。我也尝试使用notifyDataSetChanged()方法，但它不起作用。