Fetch contacts and show simultaneously - android

I am fetching contacts and this work is going fine. But I am try to also show the contacts in bunch of 50 which is fetched, i.e. user don't have to wait until all contacts has been fetched.
I try to with Asynctask , And Thread also but when I go to notify the list adapter then error has came.
"The content of the adapter has changed but ListView did not receive
a notification. Make sure the content of your adapter is not modified
from a background thread, but only from the UI thread. Make sure your
adapter calls notifyDataSetChanged() when its content changes"

Make sure you update the adapter from the onProgressUpdate() method of the AsyncTask. The onProgressUpdate() can be invoked by calling the publishProgress() from inside yourdoInBackground(). doInBackground() runs in the Background Thread, while onProgressUpdate() runs in your UI thread.

Related

Call notifyDataSetChanged after each item I receive in AsyncTask

I use an AsyncTask and on doInBackground() I have a loop where I'm doing a lot of network calls. Each call gives me a new data object that I want to add it to my listView.
I know that I can call notifyDataSetChanged() on onPostExecute() and update my list with all my items but I'm wondering if its possible to somehow call notifyDataSetChanged() when I receive a new item and update my listView the same moment and not to have to wait until all the work on doInBackground finishes.
If there isn't a way I can do this with AsyncTask then whats the proper way to deal with something like that?
Thank you
Call publishProgress(...) from doInBackground(...) and override onProgressUpdate(...) in your AsyncTask and call notifyDataSetChanged() there.
Calling publishProgress(...) from doInBackground(...) instructs the AsyncTask to call it's onProgressUpdate(...) on the main UI thread, hence you can update the ListView from there.

Activity's UI freezes on AsyncTask's onPostExecute?

I used AsyncTask to request for a large chunk of data. When received, the data is processed inside the onPostExecute method. It may take a while to process the data.
Based from my understanding, AsyncTask is asynchronous and is independent from the UI.
Why does my Activity freezes onPostExecute?
Is it normal for an Activity to freeze if processing inside the onPostExecute method is too long?
How do I make it such that my Activity won't freeze onPostExecute?
You should do all your datasource operations like(database , network ,parsing the response.etc) in doInBackground method.
If you want update any ui updation in async task the use onProgressUpdate
I think you are performing any parsing operations in onPostExecute. try getting filtered or parsed data (lighter data) in onPostExecute.
Why does my Activity freezes onPostExecute?
According your post, you perform some time consuming operation on
PostExecute method. On PostExecute is running on UI thread, so it's
okay that you UI is freezed.
Is it normal for an Activity to freeze if processing inside the onPostExecute method is too long?
Yes, it's. You should perform long operation in doInBackground method
(non-UI thread)
How do I make it such that my Activity won't freeze onPostExecute?
Try to transfer your long time operation to doInBackground method and
in PostExecute just update UI according response, which you get after
operations in doInBackground method.
see Long Running Task You Need to Bind in doInBackground here you cannot Bind UI control Like Button, ImageView etc. After completion of doInBackground in onPostExecute you can Bind All Require Control, make sure here[onPostExecute] you not runnning Another task.
Make sure you are using doInBackground method in your AsynTask method.

Network connection and UI views change in same method

I'm having problem with an AsyncTask in my app. I load some dat in doInBackground(), and with that data (contains a link to download an image) I fill a ListView. My idea was to fill the ListView in onPostExecute(), but I can't because the adapter uses a Http connection to download the image and show it.
So, if I put the adapter in onPostExecute() Android tells me that I can't make a network connection in UI main thread. But if I did it doInBackground() it tells me that only the original thread that created a view hierarchy can touch it views.
Any suggestion?

list view java.lang.IllegalStateException even after calling notifyDataSetCanged();

java.lang.IllegalStateException: The content of the adapter has changed but ListView did not receive a notification. Make sure the content of your adapter is not modified from a background thread, but only from the UI thread.
my list-view contains huge data`s
am calling the bellow code using handler when the data is changed in the list
listviewAdapter.notifyDataSetChanged();
but i get the same error some times and not every time i load it
thanks in advance
the question is not where the adapter update, it should be: the time the adapter update.
it look likes: your data bind to the adapter has be changed, and the ui have be updated, so this time, the system find the data changed but can't invoke the notifyDataSetChanged.
so, suggestion when you change the adapter's data, invoke notifyDataSetChanged immediately,
or
dont directed change the adapter's data in your thread, you should send the data to the hanlder, and in the handler using the data to replace or change the adapter's data and notifyDataSetChanged.
so anyway, suggestion get the data can run in background thread, and update the data , notifyDataSetChanged used in ui thread.
the error is quite clear. You have not to call listviewAdapter.notifyDataSetChanged(); from a thread different of the UI thread.
Modify the arguments of the adapter in runOnUIThread() or use a handler to notify the adapter that the dataset has changed.

Android Refresh UI data from AsyncTask

hi i am Using AsyncTask to download Xml's files,images from URl,after downloading xmls i am going to parse and displaying data in ListView of ImageView and TextView.i know how to update UI in
onPreExecute() onPostExecute(Void result),
if for Example i am downloading 100 xml's in doInBackground() method,i want to update List View for every 10 xml's download completed, i am using Handler to update List view by sending a message.its going to Force close due to
handlers,can any one suggest me how to do it...
Can any one tell me which is the way to solve my prob...
I wouldn't use a Handler if you're using a AsyncTask as it has already a build in mechanism to update the UI thread from the background thread.
You can pass updates to the UI thread using the onProgressUpdate() method. As onPostExecute() and onPreExecute() it is also executed on the UI thread. To pass an object to the UI thread you have to call publishProgress() within the doInBackground().

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