A Loop In A Service / AsyncTask?
Apr 8, 2013
I need a endless loop/while/for.How to do this in a AsyncTask or Service?
[HIGH]public class Back extends AsyncTask<Void, Void, Void>{
@Override
protected Void doInBackground(Void... params) {
handler.postDelayed(new B1(), 2000);
handler.postDelayed(new B2(), 3000);
return null;
}
}[/HIGH]
I want to make my handler endless loop/while/for.
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May 1, 2010
Everything is in the title.
On the official documentations it is stated that Note that services, like other application objects, run in the main thread of their hosting process and AsyncTask only works if it is executed in the UIThread.
So is it possible to use AsyncTask in a Service class? code...
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Jun 26, 2010
I have a service, that requests another class, which launches an AsyncTask
Service->Weather Class->Execute Method->Asynctask->Execute
this is launched in the service by
new Weather(this).execute(); // the execute is a method of the class, not of the AsyncTask
how do I detect in Service that the AsyncTask finished so I can call stopSelf?
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Aug 12, 2010
I have a Service that creates AsyncTasks for downloading files. In activities, we create Runnables or Threads that we pass to Activity.runOnUiThread(). I can't access that method from a service, so how do I use AsyncTask correctly, (do heavy work without blocking the UI Thread)?
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Oct 12, 2010
I have an activity which starts a service. In the service there is a network lookup in an AsyncTask. Results from the lookup are saved to a database.
The activity queries to database and shows the newest entries. But at the very first run the database is empty, so there is nothing to show. In this case I would like to show a progress dialog to the user while the network lookup is taking place. I would like to dismiss the progress dialog when the first lookup is finished.
Is there a way to access the progress dialog created in the activity from the service? Or how to do it?
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Jun 1, 2010
I was wondering if it's possible to call specific methods defined within the AsynTask class from another class and/or service ?
In my specific case I have a Service playing some sounds, but the sound is selected from a List with available sounds...
When a sounds is selected it is downloaded from my home server, this takes some time (not much, let's say around the 3-4 seconds, the sounds/effects aren't big in size)...
So my problem at the moment is that I have a service to play those sounds, and when I select one I wanted to show a progressdialog... The way (if I understood correctly) is to use an AsyncTask, but the only thing the AsyncTask will do is telling my Service to play a specific sound from my server... So there is no "callback" from the service to the Asynctask...
How can I call a running AsyncTask, which sits in another class, and tell him all work is done and thus he can stop showing the ProgressDialog ? Or am I over-engineering it and there are other ways ?
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Jul 28, 2010
I'm trying to figure out the correct way to create an AsyncTask to retrieve some data from the internet and then to take that data and bundle it up in an Intent and pass it to a new activity(A list display). So in the first activity I just have an EditText and Button. In the event of an OnClick the task should be called and when it is finished the data should be bundled inside an Intent and passed to the next Activity. The problem is when I take the results from onPostExecute and set them to an instance variable of the main activity, that instance variable is still null when the task is complete. Here is the barebones version of the code:
CODE:...........
When I debug the application I see onPostExecute does contain a valid PlacesList full of results, so why is the instance variable places set to null after the task is executed? I am going about "returning data" from an AsyncTask incorrectly?
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Apr 6, 2010
I am working on a simple application (studying purposes) which list all the files from a selected folder. On top of that I would like to have a search feature where the user can search for files (the code for that is already in place). Now, I was thinking about having the search running in the background somehow, whilst the user can still navigate, create folders, copy, sort and do other stuffs normally. When the search finishes the user would get a notification and then could click on it and go to that activity (It ideally should be the same ListView I already use for browsing the files, I would just need to update the Adapter there with the latest processed data after clicking in the notification). What's the best answer for that? Threading or AsyncTask?
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Dec 27, 2009
Can anyone point me to a good example where a AsyncTask queries a local SQLite database and then updates the UI successfully. I have a database which I query using doInBackground... create a new custom SimpleCursorAdapter (overriding onViewBind), return the adapter (SimpleCursorAdapter), then in postExecute() create ListView adapter which is set to the the SimpleCursorAdapter, that was returned, then I set the listview adapter using SetAdapter(adapter);...
For some reason I throw an exception on fillWindow.java:200....
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Jul 15, 2009
My application parse an xml file dans display data in a list view. On start of application i load data using an AsyncTask. A Progress Dialog is display during the load. This part works fine.A button in the application make it possible to reload the data. I would like to run the AsyncTask but the sytem say i can't alter view in other thread. I have also read an AsyncTask can't be run another time So i would like to know what is the best way to do this and not to have the "application not responding" message.
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Aug 9, 2010
I know this is not how an async task should behave but my question is how to "block" the user while executing it.My need is the following: I have my own backup/restore process and I have an async task to run these two actions. The backup is fine, I can warn the user when the backup is done and that's just fine But my problem is about the restore process. When the user click on restore he shouldn't be able to make any change in the application (and anyway don't want to because he would lose all his changes).I understand that having the user blocked while restoring (or maybe with a progress bar) is not a best pratice but I do not see any other possibility in this context.
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Apr 9, 2010
I know how to use AsyncTask in a standard manner to manage operations that are in the background in relation to a UI thread.However,I want to run a task in the background which might run for a very long time under certain circumstances. In these cases, I would like to force the background task to fail if it runs for an excessive amount of time.I know that I can invoke the "get(long timeout, TimeUnit unit)" method of AsyncTask in my UI thread in order to terminate my background task if it runs too long. However, in that case, my UI will block while this "get()" command is waiting.There are probably other drawbacks to directly calling "get()" in this manner, not the least of which being an evil interaction with the "done()" method of AsyncTask's contained FutureTask object, which itself is calling "get()" at least this is what I see when I look at the source code for AsyncTask.
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Jul 5, 2010
I have an activity that needs to do some stuff in the background. When the background is done, I want it to load a new activity.I can successfully kick off the async task and using using ViewSwitcher I can show a nice progress dialog.However, when the user hit 'back' or 'close' from the new task, I want them to see the main screen of this task again. So, I use the showPrevious() after I start the new Activity, but I see the screen switch from the loading window back to the main window BEFORE the new Acitivity is launched.How do I get it to switch after the new activity, or when they come back from the new activity?I tried onRestart() and onResume() but both of them seem to give me a view of -1 that I couldn't do much with.
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Sep 20, 2010
I'm running a network service within an ASyncTask. I want to be able to time the task, and after a certain period of time interrupt it.Is there a simple way to do this? Basically, when the doInBackground() methods starts, I want to say "If it hasn't completed in 30 seconds, do something else".
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Jul 29, 2009
I'm developing a game based on SurfaceView and a game thread for the whole game thing.Now I want to do some HTTP requests triggered on events inside the thread. They should of course be asynchronous, so the game doesn't stop. I found AsyncTask to be a neat way to do this but I'm having trouble implementing this at the moment. Maybe I misunderstood the concept of AsyncTask,I don't know it just drives me nuts as I read docs and blogs and still I don't get it. So sorry if that's a dumb question but I'm mad of thinking about it.
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Mar 13, 2010
while debugging and app that uses AsyncTask to record audio and update UI I noticed that everytime that an AsyncTask object ends running (finishes doInBackground and onPostExecute or on Cancelled it´s thread stays alive (running status).At least for me that should not be the behavior of the class since the doInBackground task may not stay running forever (as an example the android manual says that a status bar should be updated by an asynctask, and it won´t last for the whole app running time).Is there anything I´m missing, as a method to destroy it, or should I just ignore and keep creating threads as I need and the VM will handle them as it needs resources?
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Jul 18, 2010
When I try to compile to following code, I get two errors:
Description Resource Path Location Type
Syntax error on token "void", invalid Expression AsyncTask.java /AsyncTask Project/src/org/me/asynctask line 19 Java Problem
Description Resource Path Location Type
The type AsyncTask is not generic; it cannot be parameterized with arguments AsyncTask.java /AsyncTask Project/src/org/me/asynctask line 25 Java Problem
CODE:............
Obviously AsyncTask IS a generic (http://developer.android.com/reference/android/os/AsyncTask.html#execute so why do i get those errors?
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Jan 7, 2010
In order to get XML data from a server repeatedly, I'm attempting to use AsyncTask and Timer as per Mark Murphy's suggestion. I get the following error:01-07 16:11:26.705: ERROR/AndroidRuntime(729): Caused by: java.lang.Runtime Exception: Can't create handler inside thread that has not called Looper.prepare()I'm using SDK 1.5 with Eclipse on Windows.I've looked in documentation, on StackOverflow and in the Android Developers group, but I'm not clear what's causing the error or how to fix it.I can get the data once - i.e. without Async and Timer - and parse it via SAX without problems.s: I'm quite new to Android.
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Apr 10, 2010
My program was going wonderfully. It is a search engine that connects to our back end database by sending Get requests to our server and displays the results. I've managed to get it to query my server and back end database, return results using JSON, return the first headers and pour them into a ListView widget in the main activity. Then when the user clicks on one of the headers it then sends another query from a sub-activity. It then parse those results and format them neatly into a WebView embedded into the sub-activity.
All this works perfectly. That is until I come to make a second query on the main activity. Listed below is my stack trace of where the error happens. I think I know why this is happening, but obviously not clearly understanding it.
I think it is because I am trying to call AsyncTask again. I remember reading that the AT can only be called once, but I presumed quite wrongly that this meant you can not do concurrent calls. I thought that once an AT had done it's task it was cleared and then could be called again, but this does not seem to be the case. Is it because of AT attempts at more than one call ? If so, would I be better changing that section into a Handler with a Runnable on the main activity?
-----Stack Trace----
CODE:.....................
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Dec 16, 2009
I'm working out my first multi-threaded application using Android with the AsyncTask class. I'm trying to use it to fire off a Geocoder in a second thread, then update the UI with onPostExecute, but I keep running into an issue with the proper Context.
I kind of hobbled my way through using Contexts on the main thread, but I'm not exactly sure what the Context is or how to use it on background threads, and I haven't found any good examples on it.
Here is an excerpt of what I'm trying to do:
CODE:...........
It keeps failing at the sixth line there, because of the improper Context.
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Feb 12, 2010
When using ThreadPoolExecutor can I use AsyncTask as the Runnable in my queue? Or does this defeat the purpose?
CODE:.....................
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Mar 5, 2010
Im using HTC Hero with HTS sense. Im experience that sometimes AsyncTask not will run doInBackground method on execute();
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Mar 26, 2010
I'm confused as to when one would choose AsyncTask over a Handler. Say I have some code I want to run every n seconds which will update the UI. Why would I choose one over the other?
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Oct 12, 2010
Tell about the "asynctask" used in android application. Currently I am working on an application where I have to create a Class in which I have to just get the response of any particular URL given. I this particular class I was told to perform this task by making use of "asynctask".
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Nov 2, 2010
I'm having a problem with the AsyncTask class. It seems like my task stops working after creating 4 or 5 tasks.
Im having 2 activities. MainActivity which only holds a button that starts a second activity called ImageActivity.
ImageActivity is very simple. it got an onCreate that sets the layout, and then it starts a new AsyncTask that loads an image from the internet. This works fine the first few times. But than it suddenly stops working. The onPreExecute method is run every time, but not the doInBackground method. I have tried to simplify the doInBackground with a sleeping loop, and the same thing happens. I cant understand this behavour since the asynctask is both canceled and set to null in the onDestroy method. So every time i start a new ImageActivity, i also create a fresh AsyncTask.
I recreate the ImageActivity and the task by hitting the back button, and than clicking the button on the MainActivity.
UPDATE: Code that starts the ImageActivity (inside a button onClickListener)
CODE:...........
The code above starts this activity
CODE:.............
UPDATE:
I have tested using a combination of traditional Threads and runOnUiThread method, and it seems to work better. Now the thread runs every time.
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Nov 24, 2010
I've been using my Activity class to access my DB which made my program freeze sometimes.
So I decided to use AsyncTask instead to handle the DB.
My problem is I don't know how to instantiate my SQLite DB "TheDB" from AsyncTask's class
CODE:.............
This worked fine on the Activity class, but it I dont know how to use it here
TheDB's constructor is TheDB(Context context) but this class is not a "context" so how can i use my DB here?
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Apr 5, 2013
I read from my web space from a text file and paste it in TextView.Everything works.
But now I want the (AppWidgetProvider) in my widget insert. My widget has a TextView.
So how can I connect a AsyncTask with a AppWidgetProvider?Tried it. But the app crashes from then.
My MainActivityl.class with AsyncTask it reads. And my AppProviderWidget.class
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Apr 11, 2010
I don't understand why I'm getting this error. I'm using AsyncTask to run some processes in the background. I have:
protected void onPreExecute()
{
connectionProgressDialog = new ProgressDialog(SetPreference.this);
connectionProgressDialog.setCancelable(true);
connectionProgressDialog.setProgressStyle(ProgressDialog.STYLE_SPINNER);
connectionProgressDialog.setMessage("Connecting to site...");
connectionProgressDialog.show();
downloadSpinnerProgressDialog = new ProgressDialog(SetPreference.this);
downloadSpinnerProgressDialog.setProgressStyle(ProgressDialog.STYLE_SPINNER);
downloadSpinnerProgressDialog.setMessage("Downloading wallpaper...");....
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Sep 10, 2010
Implementing a service to handle connection changes and downloads. The service handles a queue of AsyncTasks, each representing a "download task". This way, we can cancel/pause tasks when connection drops, and also restore them when connection is reestablished. Since the threads AsyncTasks are run are not deterministic, how many ATs should I execute() at the same time?
I've read that I shouldn't reuse tasks. How can I achieve this pause->resume functionality then? Should I tell the thread to sleep? Should I make a no-op while if connection is down? I was trusting the cancel(true) method, which I've read is not reliable either.
My main DownloadTask is a subclass of AsyncTask that returns a new AsyncTask to be called when the connection is restored.
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Jul 21, 2009
I execute this async task in my application, I don't understand why my progress dialog and all application freeze. Insert in doInBackground put one hundred or so entity in database.
In other case (but it's fisrt time with sqlite).
I use AsyncTask and I have no problem.
CODE:.................
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