Hi Mark

howdy, Ataul!

how can I help you today?

I was hoping for a bit of clarification on overriding getView() please :)

specifically, when it's appropriate to call super.getView(...)

you would call super.getView() if you are extending an existing adapter class (like ArrayAdapter) and you want to *add* to what the superclass already does, rather than replace it

in your paste, what is "it's" that you want to check for null?

convertView

I'm extending SimpleCursorAdapter

if you are extending SimpleCursorAdapter, you don't override getView() at all

so I just called super.getView without checking for null

you override newView() and/or bindView()

In my understanding, getview calls newView and/or bindView?

correct

it calls newView() if there is no row ready for recycling

SimpleCursorAdapter, by default, will inflate your selected layout file in newView()

you would override that if you have more complex logic (e.g., different row layouts based upon something in the data)

bindView() is where you pour data into the row, whether that row is newly created or recycled

SimpleCursorAdapter can do a lot of that for you, without you overriding bindView(), but you are welcome to override it if you wish

in neither case do you need to worry about convertView -- you don't even see convertView

Doesn't getView supply that in one go then? Without having to call them separately?

them= new/bind

yes, at the cost of writing a lot more code

ah

and for no gain in speed

okay got you :)

another question, related if it's okay

go right ahead -- nobody else is waiting for a turn :-)

I want to fill a view with data from a contentprovider, so I launch an ASyncTask in my extension of SimpleCursorAdapter

I cache the results (and check the cache before launching the ASyncTask)

oh, that really doesn't sound good

:S

an adapter should not be spawning threads IMHO

that's the responsibility of the fragment (or activity if there are no fragments)

Could I describe my usecase for some advice?

sure

I'm using SimpleContentProvider to front a SQLite db, with 1 main table, which I use to populate the adapter using CursorLoaders.

I also need to populate one of the views in a list row, from another table

SimpleContentProvider?

the mit one: https://github.com/mitmel/SimpleContentProvider

ah, OK, that one

sorry, 3rd party lib

I know of it but have not used it

my "another table" can have many records which are related to a single record in my main table

I was going to use the ASyncTask to get all the related records, and collate the information into a single view

that sounds fine, so long as it is not the adapter starting the task

it's not a question of using AsyncTask instead of a Loader (though you could use another Loader if you wanted)

it's a question of responsibilities

an adapter is solely responsible for rendering rows in a list (or whatever you are using the adapter for)

it's not responsible for data aggregation

any more than a button is responsible for a Web service call, or an EditText is responsible for saving a file

suppose I did the aggregation in my fragment then, how might I update the adapter so it renders the currently empty view (in each row) with the newly aggregated information when it's ready?

when onLoadFinished() is called on your fragment, have the fragment start the AsyncTask

set the adapter on the list(?) in onPostExecute() of the AsyncTask

if you're saying that you want to display the list with just the initial Cursor, then augment it with additional data from the AsyncTask, that's doable but complex

yes that's exactly what I'm saying

I have a way, but it'll only update when the views get recycled

you would have to walk the existing child views of the AdapterView and update them, plus give the adapter the additional Cursors(?) or whatever the data is for when the user scrolls

where would I walk through the existing child views? Presumably I'd only have to do it for the ones that are on screen? (In my current implementation, or plan, getView() checks to see if the data is available, and sets nothing if it's not available)

"where would I walk through the existing child views?" -- something triggered by onPostExecute() of the AsyncTask

in terms of who does it... you could argue either the adapter or the fragment

as in, how could I determine which views are currently displayed?

*rows

this is a ListView?

yes

getFirstVisiblePosition() tells you the position index of the first child (getChildAt(0)) of the ListView

so, you call getChildCount() on the ListView, and iterate that many times, using getFirstVisiblePosition() as your position offset, to walk the existing rows

is there a corresponding getLastVisiblePosition()

or just do a reasonable amount

there is a getLastVisiblePosition() which you can use

awesome

is there a function on campfirenow to email the transcript? I made the mistake of leaving last time without copying it

I post the transcripts shortly after each chat at http://commonsware.com/office-hours

you'll find a couple of years' worth there :-)

ah brilliant :D

but, no, there's no email-me-a-transcript in Campfire AFAIK

ok, I think that's enough information for me to get on with for a week ish :)

Thanks a lot

sure!

what did you do prior to Android?

job-wise if you don't mind me asking

that's a bit off-topic for this chat

fair enough

thanks again, I'll be back soon no doubt

next chat is tomorrow, 7:30pm Eastern

I've got them all in my gCal

:)

ah, OK

howdy, Yurii!

there's also a chat tomorrow, 7:30pm Eastern, which may fit your schedule better

but, if you have a quick question, go ahead

is it appropriate to call startActivity in worker thread

and show dialog while it is starting

then in handler just dismiss dialog and new activity get's loaded nice and easy

probably not, if I am interpreting you correctly

let's say that you have Activity A and Activity B

Activity A is in the foreground

Activity A, from a background thread, calls startActivity() to start Activity B

if you are saying that Activity *A* tries to display a dialog, that will be pointless in most cases, as B will appear on the screen before the dialog does

(possible exception being if Activity B is in some other app)

now, Activity *B* could elect to display its own dialog on startup while it does something -- you see this a lot with ProgressDialog

yeah but then we need to handle orientation changes with asynch task and staff and I haven't figure out even if your book what is the best practice for that

you have to handle that regardless of who starts the dialog

the fact that it is Activity B instead of Activity A does not change that requirement

this is one of the reasons I try to avoid dialogs

so how do you make show progress while loading anything?

that depends on the rest of the UI

for example, if it's a ListView, use a ProgressBar as the "empty" view in the ListFragment or ListActivity

awesome, thanks a lot. That is it!

yeah, an in-fragment or in-activity progress indicator tends to be easier than a ProgressDialog

and, that's a wrap for today's chat

next chat is in ~26.5 hours :-)

have a pleasant day!