doInBackground like you have it is not the way to do that -- what you
have coded is called spinning
Kostya Vasilyev's explanation is clearer than mine and will move you
in the direction of correct code if you take the suggestion and
continue to work it but rather than doing a spin-lock as a wait
better not to null it unless absolutely sure at a level of work V. is
trying to get you to do
best is to use onPreExecute and onPostExecute as shown by Skyler a
while back and as well since this is Mult-Thread and that is dicey
without correct code then one approach is to syncronize( ObjectRef )
What about extending the async task and then implement the logic directly
in the doInbackground method?
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Yes, that's the more usual pattern.
You'll still likely need an activity reference to show progress and
display results, but there are special methods in AsyncTask for that,
which are automatically called on the UI thread - thus, you'll be
avoiding multiple threads trying to access and modify
Yes i have a indeterminate progressBar in the header, the spinner one, but
im using broadcast to all the activities which have the spinner to show or
hide it if there's a task running in the background :
@Override
protected void onPreExecute() {
You still have access to a member variable (activity) inside code that runs
on the non-UI (worker) thread.
Either:
- Do not reference the activity from doInBackground, moving the actual code
here from activity.doBackgroundRequest
- Or learn the basics the thread synchronization, so that your UI
Hi there! Yes i removed the code from activity.doBackgroundRequest to the
extending Async Tasks doInBackground, i think it might solve this, BUT i
will se the thread synchronization topic.
Thanks for the attention.
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For more options,
You cannot just use a reference(be it explicit or implicit to an inner
class definition) to an Activity in the doInBackground of an AsyncTask (or
in any method that is executed on a background thread). You'll get the
problem you see right now.
First, i would suggest trying not to use an
On Wed, Oct 26, 2011 at 9:22 AM, Streets Of Boston
flyingdutc...@gmail.com wrote:
First, i would suggest trying not to use an Activity reference in your
doInBackground at all. Maybe you can just use a Context
(activity.getApplicationContext()) instead.
Or, get the data you need out of the
Well the thing is, this Asynctask is binded to a parent activity, that the
subactivities use when they want to do some background work. They each
implement the method you see in the code i've posted, the *
activity.doBackGroundRequest(); *
I've actually had errors even after the line
Also wouldnt using the activity.getApplicationContext() result in the same
problem??? if activity is null i would stil lget the null exception???
regards,
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activity#getApplicationContext returns the Application context, which
is a reference to this class,
http://developer.android.com/reference/android/app/Application.html,
and is available for the livetime of your application.
On Oct 26, 11:40 am, Bluemercury joao.ro...@gmail.com wrote:
Also
yes, but how can i get the method from the activity that contains the logic
to do in the background from the context, is this possible? im getting null
exception for the activity after verifying if the activity is not null:
if(activity!=null){
return
This happens during orientation changes, correct?
What you have is two threads accessing and modifying the same variable
at the same time.
Take some time to learn about multithreaded programming in Java:
concurrent access and modification of a variable is one of the things
that fall under
On Wed, Oct 26, 2011 at 11:31 AM, Bluemercury joao.ro...@gmail.com wrote:
Well the thing is, this Asynctask is binded to a parent activity, that the
subactivities use when they want to do some background work. They each
implement the method you see in the code i've posted,
the
How so? each activity launches its own async task with its own specific
logicwhen you rotate you just detach the current activity from the
async task, the activity gets destroyed, a new one is created and attached
to the SAME async task
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I'm surprised Mark hasn't posted this yet. This may be of help to you,
AsyncTask and Screen Rotation
http://commonsware.com/blog/2010/09/10/asynctask-screen-rotation.html.
On Oct 26, 1:18 pm, Bluemercury joao.ro...@gmail.com wrote:
How so? each activity launches its own async task with its own
Hey Skyler, thanks for the link. so i need to get rid of activity reference
on the doInBackground...i assume its possible to use the activity reference
in the preExecute and post
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Yes, you can safely use activity references in onPreExecute and
onPostExecute, because those are run on your application's main
thread, the same thread that all framework components run on. So by
referencing your activity in onPreExecute and onPostExecute you wont
need to contend with with any
Hi again skyler, thanks for the reply, yes the code im using in the
doInBackground deals with the logic i want to do in the background that
each activity has, in this case the method doBackgroundRequest is the
method every activity uses if it wants to use an async task...but it seems
this
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