I want to Implement MovetoFirst and MovetoNext Functions for my videolist app. Can some help me here

package shashank_balaganchi.sbsvideoplayer;

/**
 * Created by shashank on 04-10-2015.
 */

import android.app.*;
import android.content.Context;
import android.content.Intent;
import android.database.*;
import android.net.Uri;
import android.os.*;
import android.provider.*;
import android.support.v4.widget.SwipeRefreshLayout;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.View;
import android.view.ViewGroup;
import android.widget.*;

public class Videolist extends Activity {

    private Cursor videoCursor;
    private int videoColumnIndex;
    ListView videolist;
    int count;
    String thumbPath;
    SwipeRefreshLayout swipeLayout;

    String[] thumbColumns = { MediaStore.Video.Thumbnails.DATA,MediaStore.Video.Thumbnails.DATA,MediaStore.Video.Thumbnails.VIDEO_ID };
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.filelist);

        initialization();
    }

    public void initialization()
    {
        System.gc();
        String[] videoProjection = { MediaStore.Video.Media._ID,MediaStore.Video.Media.DATA,
                MediaStore.Video.Media.DISPLAY_NAME,MediaStore.Video.Media.SIZE };
        videoCursor = managedQuery(MediaStore.Video.Media.EXTERNAL_CONTENT_URI,videoProjection, null, null, null);
        count = videoCursor.getCount();

        videolist = (ListView) findViewById(R.id.PhoneVideoList);
        videolist.setAdapter(new VideoListAdapter(this.getApplicationContext()));
        videolist.setOnItemClickListener(videogridlistener);
    }
     private AdapterView.OnItemClickListener videogridlistener = new AdapterView.OnItemClickListener()
     {

        public void onItemClick(AdapterView parent, View v, int position,long id)
        {
            System.gc();
            videoColumnIndex = videoCursor.getColumnIndexOrThrow(MediaStore.Video.Media.DATA);
            videoCursor.moveToPosition(position);
            String filename = videoCursor.getString(videoColumnIndex);
            Log.i("FileName: ", filename);
            Intent intent = new Intent(Videolist.this,ViewVideo.class);
                intent.putExtra("videofilename", filename);
                 startActivity(intent);
        }};

    public class VideoListAdapter extends BaseAdapter
    {
        private Context vContext;
        int layoutResourceId;

        public VideoListAdapter(Context c)
        {
            vContext = c;
        }

        public int getCount()
        {
            return videoCursor.getCount();
        }

        public Object getItem(int position)
        {
            return position;
        }

        public long getItemId(int position)
        {
            return position;
        }

        public View getView(int position, View convertView, ViewGroup parent)
        {
            System.gc();
            ViewHolder holder;
            String id = null;
            View listItemRow = null;
            if(listItemRow == null)
            listItemRow = LayoutInflater.from(vContext).inflate(R.layout.listview, parent, false);

            
            TextView txtTitle = (TextView)listItemRow.findViewById(R.id.txtTitle);
            TextView txtSize = (TextView)listItemRow.findViewById(R.id.txtSize);
            ImageView thumbImage = (ImageView)listItemRow.findViewById(R.id.imgIcon);

            videoColumnIndex = videoCursor.getColumnIndexOrThrow(MediaStore.Video.Media.DISPLAY_NAME);
            videoCursor.moveToPosition(position);
            txtTitle.setText(videoCursor.getString(videoColumnIndex));


            videoColumnIndex = videoCursor.getColumnIndexOrThrow(MediaStore.Video.Media.SIZE);
            videoCursor.moveToPosition(position);
            txtSize.setText(" Size(KB):" + videoCursor.getString(videoColumnIndex));

            int videoId = videoCursor.getInt(videoCursor.getColumnIndexOrThrow(MediaStore.Video.Media._ID));
            Cursor videoThumbnailCursor = managedQuery(MediaStore.Video.Thumbnails.EXTERNAL_CONTENT_URI,
                    thumbColumns, MediaStore.Video.Thumbnails.VIDEO_ID+ "=" + videoId, null, null);

            if (videoThumbnailCursor.moveToFirst())
            {
                thumbPath = videoThumbnailCursor.getString(videoThumbnailCursor.getColumnIndex(MediaStore.Video.Thumbnails.DATA));
                Log.i("ThumbPath: ",thumbPath);

            }
            thumbImage.setImageURI(Uri.parse(thumbPath));

            return listItemRow;

        }

    }
    static class ViewHolder {

        TextView txtTitle;
        TextView txtSize;
        ImageView thumbImage;
    }
}