CODEWITHSUNDEEP
androidrssandroid-listviewandroid-asynctask
Javacadabra
Javacadabra

Reputation: 5768

Update list with RSS data

I am working on displaying some RSS data in a ListView. I was reading up on the onProgressUpdate() method provided by the Asynchronous task class.

I was wondering if it would be possible to use this method to update the listview as each item from XML is retrieved?

I overrided the method here:

    @Override
    protected void onProgressUpdate(Integer... values) {
        adapter.notifyDataSetChanged();

    }

I am getting this error:

Caused by: android.view.ViewRootImpl$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views.

Any ideas where I am going wrong?

EDIT: I just read an article saying this error is generated from trying to update the UI thread from within the background thread inside of the doInBackground() method. In my case I am calling the onProgressUpdate() in the doInBackground() method. I was trying to add the effect of the list populating as each item was downloaded.

Any suggestions of how I could achieve this would be great!

Log cat:

01-13 00:41:09.195: E/AndroidRuntime(32239): FATAL EXCEPTION: AsyncTask #1
01-13 00:41:09.195: E/AndroidRuntime(32239): java.lang.RuntimeException: An error occured while executing doInBackground()
01-13 00:41:09.195: E/AndroidRuntime(32239):    at android.os.AsyncTask$3.done(AsyncTask.java:299)
01-13 00:41:09.195: E/AndroidRuntime(32239):    at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:352)
01-13 00:41:09.195: E/AndroidRuntime(32239):    at java.util.concurrent.FutureTask.setException(FutureTask.java:219)
01-13 00:41:09.195: E/AndroidRuntime(32239):    at java.util.concurrent.FutureTask.run(FutureTask.java:239)
01-13 00:41:09.195: E/AndroidRuntime(32239):    at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:230)
01-13 00:41:09.195: E/AndroidRuntime(32239):    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1080)
01-13 00:41:09.195: E/AndroidRuntime(32239):    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:573)
01-13 00:41:09.195: E/AndroidRuntime(32239):    at java.lang.Thread.run(Thread.java:856)
01-13 00:41:09.195: E/AndroidRuntime(32239): Caused by: android.view.ViewRootImpl$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views.
01-13 00:41:09.195: E/AndroidRuntime(32239):    at android.view.ViewRootImpl.checkThread(ViewRootImpl.java:4746)
01-13 00:41:09.195: E/AndroidRuntime(32239):    at android.view.ViewRootImpl.requestLayout(ViewRootImpl.java:823)
01-13 00:41:09.195: E/AndroidRuntime(32239):    at android.view.View.requestLayout(View.java:15468)
01-13 00:41:09.195: E/AndroidRuntime(32239):    at android.view.View.requestLayout(View.java:15468)
01-13 00:41:09.195: E/AndroidRuntime(32239):    at android.view.View.requestLayout(View.java:15468)
01-13 00:41:09.195: E/AndroidRuntime(32239):    at android.view.View.requestLayout(View.java:15468)
01-13 00:41:09.195: E/AndroidRuntime(32239):    at android.widget.RelativeLayout.requestLayout(RelativeLayout.java:318)
01-13 00:41:09.195: E/AndroidRuntime(32239):    at android.view.View.requestLayout(View.java:15468)
01-13 00:41:09.195: E/AndroidRuntime(32239):    at android.widget.AbsListView.requestLayout(AbsListView.java:1819)
01-13 00:41:09.195: E/AndroidRuntime(32239):    at android.widget.AdapterView$AdapterDataSetObserver.onChanged(AdapterView.java:813)
01-13 00:41:09.195: E/AndroidRuntime(32239):    at android.widget.AbsListView$AdapterDataSetObserver.onChanged(AbsListView.java:5958)
01-13 00:41:09.195: E/AndroidRuntime(32239):    at android.database.DataSetObservable.notifyChanged(DataSetObservable.java:37)
01-13 00:41:09.195: E/AndroidRuntime(32239):    at android.widget.BaseAdapter.notifyDataSetChanged(BaseAdapter.java:50)
01-13 00:41:09.195: E/AndroidRuntime(32239):    at android.widget.ArrayAdapter.notifyDataSetChanged(ArrayAdapter.java:286)
01-13 00:41:09.195: E/AndroidRuntime(32239):    at com.example.simplerss.MainActivity$PostTask.onProgressUpdate(MainActivity.java:148)
01-13 00:41:09.195: E/AndroidRuntime(32239):    at com.example.simplerss.MainActivity$PostTask.doInBackground(MainActivity.java:123)
01-13 00:41:09.195: E/AndroidRuntime(32239):    at com.example.simplerss.MainActivity$PostTask.doInBackground(MainActivity.java:1)
01-13 00:41:09.195: E/AndroidRuntime(32239):    at android.os.AsyncTask$2.call(AsyncTask.java:287)
01-13 00:41:09.195: E/AndroidRuntime(32239):    at java.util.concurrent.FutureTask.run(FutureTask.java:234)
01-13 00:41:09.195: E/AndroidRuntime(32239):    ... 4 more

Upvotes: 0

Views: 112

Answers (1)

A--C
A--C

Reputation: 36449

In my case I am calling the onProgressUpdate() in the doInBackground() method.

You have to call publishProgress() instead. If you directly call onProgressUpdate(), that is still running from the background thread and so, will fail.

You should take a look at the AsyncTask documentation, they provide an example.

Upvotes: 2

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