我AsyncTask在我的ListView.
这一切正常，但我不明白为什么我必须在方法中检查我的mHolder.hPositionvs 。如果我不检查这些值，我会得到不正确的旧图像循环- 但是如果它们被调用相同，为什么它们并不总是相等？mPositiononPostExecuteListItemsmHolder.hPositionmPositionAsyncTask
这是我的精简代码：
@Override
public View getItemView(final int position, View convertView, final ViewGroup parent) {
final ViewHolder holder;
final Job job = (Job) getStore().get(position);
if (convertView == null) {
// New List Item
holder = new ViewHolder();
convertView = getInflater().inflate(ITEM_LAYOUT, parent, false);
holder.hPosition = position;
holder.hImageView = (ImageView) convertView.findViewById(R.id.app_component_joblistitemview_logo);
convertView.setTag(holder);
} else {
// Recycled List Item
holder = (ViewHolder) convertView.getTag(); // get the ViewHolder that is stored in the Tag
holder.hPosition = position;
}
holder.hImageView.setImageBitmap(null); // set the list item's image to be blank
new DownloadImageTask().execute(position, holder); // async download the image
return convertView;
}
// DownloadImageTask
private class DownloadImageTask extends AsyncTask<Object, Void, Integer> {
Integer mPosition;
ViewHolder mHolder;
@Override
protected Integer doInBackground(Object... params) {
mPosition = (Integer)params[0];
mHolder = (ViewHolder)params[1];
// Download the Image ...
// ...
return 1;
}
protected void onPostExecute(Integer result) {
// >> This is the Spot I am Asking About <<
// Shouldn't mHolder.hPosition ALWAYS be equal to mPosition, since it's still the same AsyncTask?
// Why are mHolder.hPosition and mPosition often not equal?
if (mHolder.hPosition==mPosition) {
// ... update the List View Item
}
}
}