Question

Can anybody tell me why my Async task fails sometimes like this?
I tested it on 3 devices but this error never occured for me.
I uploaded to GooglePlay and after 200 downloads there are 3 error reports with this thing, i dont know yet what the main source of the error…

java.lang.RuntimeException: An error occured while executing doInBackground()
    at android.os.AsyncTask$3.done(AsyncTask.java:200)
    at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:274)
    at java.util.concurrent.FutureTask.setException(FutureTask.java:125)
    at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:308)
    at java.util.concurrent.FutureTask.run(FutureTask.java:138)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1088)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:581)
    at java.lang.Thread.run(Thread.java:1019)
    Caused by: android.view.ViewRoot$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views.
    at android.view.ViewRoot.checkThread(ViewRoot.java:3225)
    at android.view.ViewRoot.invalidateChild(ViewRoot.java:760)
    at android.view.ViewRoot.invalidateChildInParent(ViewRoot.java:786)
    at android.view.ViewGroup.invalidateChild(ViewGroup.java:2511)
    at android.view.View.invalidate(View.java:5498)
    at android.view.View.setBackgroundDrawable(View.java:7845)
    at android.view.View.setBackgroundResource(View.java:7754)
    at com.KeySoft.NewPilates.Activities.LatestActivity.parseXml(LatestActivity.java:1106)
    at com.KeySoft.NewPilates.Activities.LatestActivity.access$1(LatestActivity.java:964)
    at com.KeySoft.NewPilates.Activities.LatestActivity$DownloadXml.doInBackground(LatestActivity.java:354)
    at com.KeySoft.NewPilates.Activities.LatestActivity$DownloadXml.doInBackground(LatestActivity.java:1)
    at android.os.AsyncTask$2.call(AsyncTask.java:185)
    at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:306)

I see that my AsyncTaks’s *doInBackground* function there is a setBackgroundDrawable and setBacktroundResource func that do someting not verry well… any ideas?

E D I T:

Got solution from the checked answer:

I must use a new Runnable to modify the views inside from doInBackround.

runOnUiThread(new Runnable() {
             public void run() {

                 LinearLayout hatterLayout = (LinearLayout)findViewById(R.id.hatterLayout);
                hatterLayout.setBackgroundResource(R.drawable.nonet);

            }

Answer 1

You are trying to do UI-related work (manipulating Views) on the background thread. setBackgroundDrawable() and setBackgroundResource() are methods of the View class, not ASyncTask.

You can’t do this. Have a look at runOnUiThread() as a way of instigating UI updates from a background thread in the general case.

But for an ASyncTask specifically, there are already convenient hooks for you to do stuff on the UI thread. You should think about overriding onProgressUpdate() and onPostExecute(), and doing your UI work in there.