public class DecodeTask extends AsyncTask<String, Void, Bitmap> {

private static int MaxTextureSize = 2048; /* True for most devices. */

public ImageView v;

public DecodeTask(ImageView iv) {
    v = iv;
}

protected Bitmap doInBackground(String... params) {
    BitmapFactory.Options opt = new BitmapFactory.Options();
    opt.inPurgeable = true;
    opt.inPreferQualityOverSpeed = false;
    opt.inSampleSize = 1;

    Bitmap bitmap = null;
    if(isCancelled()) {
        return bitmap;
    }

    opt.inJustDecodeBounds = true;
    BitmapFactory.decodeFile(params[0], opt);
    while(opt.outHeight > MaxTextureSize || opt.outWidth > MaxTextureSize) {
        opt.inSampleSize++;
        BitmapFactory.decodeFile(params[0], opt);
    }
    opt.inJustDecodeBounds = false;

    bitmap = BitmapFactory.decodeFile(params[0], opt);
    return bitmap;
}

@Override
protected void onPostExecute(Bitmap result) {
    if(v != null) {
        v.setImageBitmap(result);
    }
}

}

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    ImageView iv = null;
    if(convertView == null) {
        convertView = getLayoutInflater().inflate(R.id.your_view, null); /* Inflate your view here */
        iv = convertView.findViewById(R.id.your_image_view);
    } else {
        iv = convertView.findViewById(R.id.your_image_view);
        DecodeTask task = (DecodeTask)iv.getTag(R.id.your_image_view);
        if(task != null) {
            task.cancel(true);
        }
    }
    iv.setImageBitmap(null);
    DecodeTask task = new DecodeTask(iv);
    task.execute(getItem(position) /* File path to image */);
    iv.setTag(R.id.your_image_view, task);

    return convertView;
}

listView.setOnScrollListener(new OnScrollListener() {
  @Override
  public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount,
      int totalItemCount) {
    // Don't care.
  }

  @Override
  public void onScrollStateChanged(final AbsListView view, int scrollState) {
    // Load images here. ListView can tell you what rows are visible, you load images for these rows and update corresponding View-s.
  }
})

private class CallService extends AsyncTask<String, Integer, String>
         {
                protected String doInBackground(String... u)
                {
                    fetchReasons();
                    return null;
                }
                protected void onPreExecute()
                {
                    //Define the loader here.

                }
                public void onProgressUpdate(Integer... args)
                {
                }
                protected void onPostExecute(String result)
                {
                    //remove loader
                    //Add data to your view.
                }
         }

public void fetchReasons()
    {
         //Call Your Web Service and save the records in the arrayList
    }

@Override
public long getItemViewType(int position) {
     return position;
}
@Override
public long getItemViewCount(int position) {
     return getCount();
}
@Override
public View getView(int position, View convertView, ViewGroup arg2) {
    if (convertView == null) {
        //inflate your convertView and set everything
    }
    //do not do anything just return the convertView
    return convertView;
}