Office Hours — Today, April 25

Apr 25	7:25 PM
Mark M.	has entered the room
Mark M.	turned on guest access
Apr 25	7:30 PM
wuqiang	has entered the room
wuqiang	Hi , morning
wuqiang	In china now is morning
wuqiang	..... good afternoon
Mark M.	hello, wuqiang!
Mark M.	how can I help you today?
wuqiang	View paste (16 more lines) `public void onViewCreated(View view, @Nullable Bundle savedInstanceState) { super.onViewCreated(view, savedInstanceState); new Thread(new Runnable() { @Override public void run() { // Fetch data from website BmobQuery<Restaurant> query = new BmobQuery<Restaurant>(); query.setLimit(10); query.findObjects(new FindListener<Restaurant>() { @Override public void done(List<Restaurant> object, BmobException e) { if (e == null) { // Success for (Restaurant restaurant : object) { ...`
Apr 25	7:35 PM
Mark M.	let me guess: you are having problems with notifyDataSetChanged()
wuqiang	View paste `This is a snippet of code fetch data from website ,I want it work in another Thread ? and I want the Adapter began to work only after the data have fetched ,Am i doing it the right way?`
Mark M.	you cannot call notifyDataSetChanged() on a background thread
Mark M.	at least, assuming that restaurantAdapter is a ListAdapter of some form
Mark M.	so, that little bit of work needs to be done on the main application thread
Mark M.	there are many options for this
Mark M.	I outline them in my chapter on threads
wuqiang	it is a RecyclerView's Adapter
Mark M.	I have not tried calling notifyDataSetChanged() on a RecyclerView.Adapter
Mark M.	(on a background thread, that is)
Mark M.	I would expect it to have the same problems as would ListView and a ListAdapter
Mark M.	with a crash saying that you are modifying the views from a thread other than the thread that created them
Mark M.	but, perhaps they added something to RecyclerView that handles this issue for you
Mark M.	I do not know much about BmobQuery, BmobException, etc., so I do not know if you have any problems with that
Apr 25	7:40 PM
Mark M.	you are modifying the restaurants collection from a background thread, and presumably you are accessing it from the main application thread, so you would need to use some sort of synchronization there
Mark M.	or, if you wind up moving notifyDataSetChanged() to the main application thread, update the restaurants collection on the main application thread as well
wuqiang	and after annotating "restaurantAdapter.notifyDataSetChanged();" ,it doesn't work
wuqiang	have noting to show
wuqiang	and where should i put restaurantAdapter.notifyDataSetChanged(); in main Thread ?
Mark M.	options for moving that code to the main application thread include: switching from Thread to AsyncTask, using post() on some view, using runOnUiThread() on your activity, and using an event bus
Mark M.	I cover all of those in my chapter on threads in the book
Mark M.	(pages 523-547 of Version 8.5 of the book)
Apr 25	7:45 PM
wuqiang	thanks
wuqiang	let me have a look
wuqiang	and i have no question today
wuqiang	Thands a lot
wuqiang	Thanks a lot
Mark M.	happy to help!
Apr 25	8:20 PM
Rick	has entered the room
Apr 25	8:25 PM
Mark M.	hello, Rick!
Mark M.	do you have a quick question?
Rick	Hi! I did but my 3 year old is screaming. I'll have to try again next time.
Mark M.	OK
Rick	Thanks though.
Mark M.	tell your 3-year-old that I said "shhh -- it'll be OK" :-)
Rick	He doesn't know "shhh"
Rick	Next office hour's when?
Mark M.	Saturday at 4pm US Eastern
Rick	okay, thank you
Apr 25	8:30 PM
Mark M.	that's a wrap for today's chat
Mark M.	the transcript will go up on https://commonsware.com/office-hours/
Mark M.	have a pleasant day!
wuqiang	has left the room
Rick	has left the room
Mark M.	turned off guest access

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Office Hours — Today, April 25

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