[英]Updating ListView Adapter from AsyncTask
what I have is an AsyncTask,
that started as soon as ListView
reached bottom item on a screen, and in AsyncTask
it adds new items to the ListView.
我所拥有的是一个
AsyncTask,
它在ListView
到达屏幕底部的项目后立即开始,并且在AsyncTask
它将新项目添加到ListView.
Here is the code: 这是代码:
@Override
protected void onPostExecute(final List<ItemDailyRecord> records) {
super.onPostExecute(records);
((ActivityHome)context).runOnUiThread(new Runnable() {
public void run() {
for (ItemDailyRecord p : records) {
adapter.add(p);
}
adapter.notifyDataSetChanged();
}
});
}
@Override
protected List<ItemDailyRecord> doInBackground(Void... voids) {
DbAdapterDailyRecord db = new DbAdapterDailyRecord(context);
List<ItemDailyRecord> list = db.getRecordsFromTo(offset, count);
return list;
}
here is a method from ListView Adapter: 这是ListView Adapter中的方法:
@Override
public View getView(int position, View convertView, ViewGroup parent) {
if(position == getCount() - 1 && hasMoreItems){
HistoryLoaderTask t = new HistoryLoaderTask(position + 1, pageSize, getContext(),this);
t.execute();
footer.setText("Loading . . .");
}
And the error message is(if I scroll the listview too fast :) 错误消息是(如果我滚动列表视图的速度太快:)
Caused by: android.view.ViewRootImpl$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views.
原因:android.view.ViewRootImpl $ CalledFromWrongThreadException:只有创建视图层次结构的原始线程才能触摸其视图。
any ideas how to solve this issue? 任何想法如何解决这个问题?
The onPostExecute()
method is executed on the UI thread, so you should be updating the UI directly in this method; onPostExecute()
方法是在UI线程上执行的,因此您应该直接在此方法中更新UI。 no need to spawn a new Runnable
object. 无需生成新的
Runnable
对象。
You shouldn't execute your async task from getView of your adapter. 您不应该从适配器的getView执行异步任务。 Instead you should try to do it from your activity/fragment where your list resides by using getLastVisiblePosition() of ListView
相反,您应该尝试使用ListView的getLastVisiblePosition()从列表所在的活动/片段中进行操作
Like this ---> 像这样--->
if(list.getLastVisiblePosition() == (dataSet.size() - 1)) {
// last item displayed
.... change the text off footer and execute async task
}
and in the async task append the extra data to dataset and then call notifyDataSetChanged() on the adapter. 然后在异步任务中将额外的数据追加到数据集,然后在适配器上调用notifyDataSetChanged()。
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