How to use asyncTask to load images from resources

Here in this custom adapter, in my list view there is only one imageview. i am loading a list of images in this listview. i want to load new images in asynctask but idont know how to implement asynctask and most the tutorials refers to image downloading but i am using drawable resources, so kindly guide me through this how do i implement asynchronous loading of images to replace image in current visible view.

class MyAdapter extends BaseAdapter {

    private Context context;
    private int images[];

    public MyAdapter(Context context, int images[]) {
        this.context = context;
        this.images = images;
    }

    @Override
    public int getCount() {
        // TODO Auto-generated method stub
        return images.length;
    }

    @Override
    public Object getItem(int position) {
        // TODO Auto-generated method stub
        return images[position];
    }

    @Override
    public long getItemId(int position) {
        // TODO Auto-generated method stub
        return position;
    }

    class MyViewHolder {
        ImageView imageView;

        public MyViewHolder(View v) {
            // TODO Auto-generated constructor stub
            imageView = (ImageView) v.findViewById(R.id.imgView);
        }
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        // TODO Auto-generated method stub
        View row = convertView;
        MyViewHolder holder = null;
        if (row == null) {
            LayoutInflater inflater = (LayoutInflater) context
                    .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            row = inflater.inflate(R.layout.custom_list, parent, false);

            holder = new MyViewHolder(row);
            row.setTag(holder);
        } else {
            holder = (MyViewHolder) row.getTag();
            row = convertView;
        }
        holder.imageView.setImageResource(images[position]);
        return row;
    }
}

and here is my MainActivity where I am calling MyAdapter to get that list of images.

public class MainActivity extends Activity {

    private ListView listView;
    private MyAdapter myAdapter;

    int[] images = { R.drawable.img001, R.drawable.img002, R.drawable.img003,
            R.drawable.img004, R.drawable.img005, R.drawable.img006,
            R.drawable.img007, R.drawable.img008, R.drawable.img009,
            R.drawable.img010, R.drawable.img011, R.drawable.img012,
            R.drawable.img013, R.drawable.img014, R.drawable.img015,
            R.drawable.img016, R.drawable.img017, R.drawable.img018,
            R.drawable.img019, R.drawable.img020, R.drawable.img021,
            R.drawable.img022, R.drawable.img023, R.drawable.img024,
            R.drawable.img025, R.drawable.img026, R.drawable.img027,
            R.drawable.img028, R.drawable.img029, R.drawable.img030,
            R.drawable.img031, R.drawable.img032, R.drawable.img033,
            R.drawable.img034, R.drawable.img035, R.drawable.img036,
            R.drawable.img037, R.drawable.img038, R.drawable.img039,
            R.drawable.img040, R.drawable.img041, R.drawable.img042,
            R.drawable.img043, R.drawable.img044, R.drawable.img045,
            R.drawable.img046, R.drawable.img047, R.drawable.img048,
            R.drawable.img049, R.drawable.img050, R.drawable.img051,
            R.drawable.img052, R.drawable.img053, R.drawable.img054,
            R.drawable.img055, R.drawable.img056, R.drawable.img057,
            R.drawable.img058, R.drawable.img059, R.drawable.img060,
            R.drawable.img061, R.drawable.img062, R.drawable.img063,
            R.drawable.img064, R.drawable.img065, R.drawable.img066,
            R.drawable.img067, R.drawable.img068, R.drawable.img069,
            R.drawable.img070, R.drawable.img071, R.drawable.img072,
            R.drawable.img073, R.drawable.img074, R.drawable.img075,
            R.drawable.img076, R.drawable.img077, R.drawable.img078,
            R.drawable.img079, R.drawable.img080, R.drawable.img081,
            R.drawable.img082, R.drawable.img083, R.drawable.img084,
            R.drawable.img085, R.drawable.img086, R.drawable.img087,
            R.drawable.img088, R.drawable.img089, R.drawable.img090,
            R.drawable.img091, R.drawable.img092, R.drawable.img093,
            R.drawable.img094, R.drawable.img095, R.drawable.img096,
            R.drawable.img097, R.drawable.img098, R.drawable.img099,
            R.drawable.img100 };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);     
        myAdapter = new MyAdapter(this, images);
        listView = (ListView) findViewById(R.id.imgList);
        listView.setAdapter(myAdapter);
    }
  }