Android :: Async Thread Aborted After Catching (all?) Exceptions
Nov 11, 2009
I have the following code...
CODE:.................
My mClient get method is a simple HttpClient execute with an output buffer to read the input stream, so it's very trivial. Everytime I execute this task UnknownHostException will be triggered which will in turn call onTaskError on my currect Activity, but I still get a RuntimeException, but I don't see why. Maybe it's because it's late and i've done about 12 hours of writing code so it's something simple I just can't see?
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Aug 12, 2009
In my application I would like to catch all exceptions globally - it should not matter, where those exceptions occur. Some runtime exceptions are practically impossible to catch (OutOfMemoryError for instance), but I want to show an informative dialog and resume execution at some well-defined point (main menu activity or something).
Using Thread.setDefaultUncaughtExceptionHandler() does this for background threads, but it is of no help in the UI thread (or adjacent handlers). If an exception occurs in the UI thread, the UI will be jammed - not reacting to any key or touch events anymore. Of course, this seems natural since it did not catch that exception; but I wonder if there is a way to recover the UI thread. So:
- Can I recover / restart the UI thread after an uncaught exception (from another thread) ?
- Is there another way to catch uncaught exceptions globally ?
- Are there viable alternatives to handle this problem ?
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Mar 12, 2010
I've a piece of code that launches an Intent. I'm wondering if there's any way to get return codes and/or catch exceptions? The particular scenario I'm facing is when I launch an Intent passing a 'rtsp' URL but it turns out the URL isn't available.
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Oct 31, 2010
I noticed that a toast isn't displayed when it's used inside a catch block.
Does anyone know how to show toasts when catching exceptions?
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Jul 16, 2010
What is the difference between Service, Async Task & Thread. If i am not wrong all of them are used to do some stuff in background. So, how to decide which to use and when?
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Mar 5, 2010
I have a simple app and I'm using the AsyncTask to test out a background process, for clearness purposes I've opted to put my AsyncTask in a separate class rather than in an inner class, which where my problems begin, this is my AsyncTask. Code...
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Apr 11, 2010
Hello, I use a thread for drawing to the canvas. By coincidence I recognized that in the program always jumps into the finally part. After view.onDraw(c); is reached it steps back to synchronized (surfaceHolder) and then it steps into the finally part. This happens every time. This means to me that every time exceptions are thrown.
Can anybody explain why this is so?
CODE:......................
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Apr 24, 2010
I've got an Android activity which grabs an RSS feed from a URL, and uses the SAX parser to stick each item from the XML into an array. This all works fine but, as expected, takes a bit of time, so I want to use AsyncActivity to do it in the background. The line items = parser.getItems() works fine - items being the arraylist containing each item from the XML. The problem I'm facing is that on starting the activity, the ProgressDialog which i create in onPreExecute() isn't displayed until after the doInBackground() method has finished. i.e. I get a black screen, a long pause, then a completely populated list with the items in. Why is this happening? Why isn't the UI drawing, the ProgressDialog showing, the parser getting the items and incrementally adding them to the list, then the ProgressDialog dismissing?
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Feb 23, 2010
Im using a web service, so I want to use an async thread for the HTTP authentication request and another thread later to make additional service requests while my main thread runs.Would like to see a good example of how to do this and how to show busy messages somehow in main app. How does the main app know when the thread finished? And what if my thread encounters exceptions, how do I deal with that?HTTP requests are sent later, use the same cookies setup up by the first auth request, so will the later requests pick up the same cookies and just work?
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Nov 22, 2010
I just have a concern about AsycnTask. If i have one activity which starts a async task. Now that activity goes in background and new activity gets opened & visible to us.
So the async task opened by previous activity stops or it still keeps going in background or it pauses or stops ?
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Dec 21, 2009
In the documentation, I read that it is not possible for executing 2 Async Tasks. If execute is called again, it should throw an exception.
The following is given under the heading of "Threading Rules", and i quote:
"The task can be executed only once (an exception will be thrown if a second execution is attempted.)"
I wish to understand the meaning of this statement.
Does this mean, that if i try and execute the same task twice (concurrently) when the first execution of the task was still going on...an exception will be thrown ? Will i need to wait for the completion of the first task, before i spawn a second task ?
A possible use case:
The user wishes to download a set of files. He clicks on the download button by providing the URL. When the first download is still going on, he wishes to download another file and provides another URL. Both these user actions are serviced by a DownloadTask, that extends the AysncTask.
If i wish to change this default behavior, is there a configuration option?
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Jun 4, 2010
How do you create unit tests for an Android activity that starts async tasks in onCreate? I would like to test the result of these tasks.
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Jul 14, 2009
I am developing a program that needs async socket. I am new to Android and Java. As I can see in the document, to write network program, I got Socket and SocketChannel, but it seems they are all sync socket, it means, I need an extra thread to call blocking read, write... and etc. Here comes the problem, my program is a chat room, the communicate is not linear, I have no idea when the server will send a message to me, if I read in that thread to wait message from server, but the user want to send message to server, the reading function blocked forever, if there is no incoming data, then the pending outgoing message will not be sent. That's why I need async socket. So my question is: How to write async socket under Android environment?
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Jul 28, 2010
I've got the URL of a .png image, that needs to be downloaded and set as a source of an ImageView. I'm a beginner so far, so there are a few things I don't understand:
1) Where do I store the file?
2) How do I set it to the ImageView in java code?
3) How to correctly override the AsyncTask methods?
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Jun 12, 2010
I read somewhere (and have observed) that starting threads is slow. I always assumed that AsyncTask created and reused a single thread because it required being started inside the UI thread.The following (anonymized) code is called from a ListAdapter's getView method to load images asynchronously. It works well until the user moves the list quickly, and then it becomes "janky".final File imageFile = new File(getCacheDir().getPath() + "/img/" + p.image);image.setVisibility(View.GONE);view.findViewById(R.id.imageLoading).setVisibility(View.VISIBLE);
(new AsyncTask<Void, Void, Bitmap>() {
@Override
protected Bitmap doInBackground(Void... params) {
try {Bitmap image;
if (!imageFile.exists() || imageFile.length() == 0) {
image = BitmapFactory.decodeStream(new URL(
"http://example.com/images/"
+ p.image).openStream());
image.compress(Bitmap.CompressFormat.JPEG, 85,
new FileOutputStream(imageFile));
image.recycle();
}image = BitmapFactory.decodeFile(imageFile.getPath(),
bitmapOptions);
return image;
} catch (MalformedURLException ex) {
// TODO Auto-generated catch block
ex.printStackTrace();
return null;
} catch (IOException ex) {
// TODO Auto-generated catch block
ex.printStackTrace();
return null;
@Override
protected void onPostExecute(Bitmap image) {
if (view.getTag() != p) // The view was recycled.
return;
view.findViewById(R.id.imageLoading).setVisibility(
View.GONE);
view.findViewById(R.id.image)
.setVisibility(View.VISIBLE);
((ImageView) view.findViewById(R.id.image))
.setImageBitmap(image);
}}).execute();I'm thinking that a queue-based method would work better, but I'm wondering if there is one or if I should attempt to create my own implementation.
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Nov 2, 2010
In my android application i am using a loading screen,processed by Async task.In do in background of this task i would like to display a alert whenever an upgraded version exist in the server.
Could you please let me know if there is any way that i can do it in android.
The code is.
CODE:.................
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May 5, 2009
I am trying to write a code about catch lat. and long. points with the GPS, actually I am using the shell with the commands "geo fix" because the DDMS doesn't work in linux apparently, I am using this scripts:
getBestProvider(criteria, true); getLastKnownLocation(provider); requestLocationUpdates(provider, 2000, 10, locationListener);
The questions is: the program is working right now in the emulator, but what about if I move the program to the real cellphone? Is the same? I need think in something else?
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Oct 10, 2010
I have been searching for an answer for this for some time now. I have an async task that downloads the database needed for my app, while this is downloading my app cant do anything as all the data it references is in this file, i have the app waiting for the file to be downloaded but i am attempting to show a progress dialog so the user knows something is happening while they wait for this to happen.however nothing shows up i have also tried directly calling ProgressDialog.show in the pre execute and moving this to the calling activity with no luck.
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Oct 15, 2010
I am (supposedly) catching NullPointerException and returning 0 if that happens. But occasionally I get NullPointerException failure anyway. Is catching it this way no enough to prevent this failure?
private char getCharBehindCursor (int offset){ // get a single char behind cursor + offsett CharSequence cSeq; InputConnection inputConnection = getCurrentInputConnection(); if (inputConnection != null){ try { cSeq = inputConnection.getTextBeforeCursor (offset + 1, 0); } catch (NullPointerException npe) { /* failure*/ return (char)0; }
if (cSeq.length() == offset+1){ return cSeq.charAt(0); } } return (char)0;
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Mar 18, 2009
I have tried all day to capture a trackball event in a View. Basically I want to use the trackball to move a Sprite in a 2D game left and right. The onTouchEvent works perfectly well in the View to move the Sprite with my finger but it would be nicer and cleaner to use the trackball.Can anyone provide me with a simple example that uses the trackball to move something in a View in a 2D type game world (not a menu or UI type of example)? Or can someone explain what I'm not doing. Thanks so much for any help you can give me.
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Aug 2, 2009
I've got this problem: When my program using too much memory, it die. Is there an exception or something else to warn me? How can I catch it?
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Aug 22, 2009
I am getting an outofmemory error (java.lang.outofmememoryerror) from a bitmapfactory that doesn't seem to be caught despite the fact that it is in a try{ }catch block. Can I catch this error somehow or is it outofmemory inherently uncatchable?
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Jul 9, 2009
I want my app to catch downloads of a particular kind of file.
Here's the corresponding part of AndroidManifest.xml:
CODE:............
Now, open a page with a link to an .exe file, click it. The download manager starts and then tells that The content is not supported on the phone. My activity doesn't even get called.
The questions are:
1) Why doesn't my activity get called?
2) What's the correct way of letting download manager do it's job and then get notified upon file download completion?
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Aug 21, 2009
I want to listen the android standard exceptions to manage it. But I don't put try/cath in all my code. Anyone knows if i can redirect the error output to my code. I've seen this System.setErr method, but It doens't works for this purpouse.
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Nov 24, 2010
when I call web service from my machine using 'localhost' or 127.0.0.1 , I got exception. But if I give the public IP, it works fine. Why it is happening?And also, If I use my public IP, I can't access web service. But If I put the same code in another machine, and call that web service using the IP address of that machine, It works fine.
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Aug 9, 2010
I'm a novice Android programmer, and to help me understand how Intents really work, I wanted to put together a small Activity which would let the user call startActivity() with any action and data they want. I tried many different combinations, including "android.intent.action.VIEW" and "http://www.google.com". No matter what combinations I use, I always get an ActivityNotFoundException. Any ideas as to why?
The code in my only Activity is below....
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Oct 15, 2010
I love the feature where we can inspect any exceptions for app's published on the market through the developer site but curious as to whether we can tap into this feature for app's we don't publish to the market so we can email any exception details to a specific email address for example.
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Mar 17, 2009
I am trying to intercept xml links that are clicked in the android web browser. I want my activity to handle these xml files, however I cannot seem to get this to work. Whenever I click on the xml file in the browser it just displays the xml file.Here is the entry that I have in my AndroidManifest.xml. Is this enough or do I need to do something more?
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Sep 7, 2010
How can I implement a run() method of thread if I create a Thread Global?
I mean If I create a Thread Globally then can I implement its run() method {" public void run()"} anywhere in my Application?
In the run() method I have to write the code to perform some action.
IF I can do it then please can anyone show me briefly how to do it particularly.
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Jul 30, 2013
I have read quite a good books & blogs about the Background work process in Android and updating the UI.
I have learned few way like using a Service with Intent, Using AsynTask, Using a Bind Service with a Intent and so..
What is the rule of thumb using this, i mean when to use what?
I am just learning to code in JAVA & Android.
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