[android-developers] Re: notifyDataSetChanged() not updating listview after orientation change

Wait, what exactly should I be returning with
onRetainNonConfigurationInstance? Wouldn't anything I return with
that be from the original activity, not the new one? So wouldn't that
cause the same problem?

Bara

On Jun 21, 7:27 pm, Streets Of Boston <flyingdutc...@gmail.com> wrote:
> This probably happens because your runnable 'mUpdateDisplayRunnable'
> has an implicit reference to 'this' activity that calls
> 'this.updateDisplay()' in its run() method.
>
> When an orientation-change happens the current activity ('this') is
> destroyed  a brand-new activity is created. When the handler
> ('mHandler') finally executes your old 'mUpdateDisplayRunnable' after
> the rotation change, the 'mUpdateDisplayRunnable' still has an
> implicit reference to the destroyed activity. This will cause the list-
> view of the destroyed activity to be updated, not the list-view of the
> new activity.
>
> In other words, the instance that is referred to by
> 'mUpdateDisplayRunnable' should be a static instance that does not
> have a reference to 'this' activity. To get hold of the current active
> (and not destroyed) activity, use either a static variable or use the
> onRetainNonConfigurationInstance/getLastNonConfigurationInstance
> methods.
>
> On Jun 20, 10:35 pm, Bara <bara.kath...@gmail.com> wrote:
>
> > Hello all,
>
> > I have a semi-complicated problem and hoping that someone here will be
> > able to help me.
>
> > On a click event I create a thread and start a long-running operation
> > based on this method (http://jnb.ociweb.com/jnb/jnbJan2009.html).
> > After the long-running task is completed, it does a callback to
> > another method, which does a post to the handler:
>
> > @Override
> > public void contentSearchModelChanged(Model_ContentSearch csm,
> > ArrayList<Class_Reminder> newRemindersList) {
> >     remindersList = newRemindersList;
> >     mHandler.post(mUpdateDisplayRunnable);}
>
> > Which calls a Runnable:
>
> > // post this to the Handler when the background thread completes
> > private final Runnable mUpdateDisplayRunnable = new Runnable() {
> >   public void run() {
> >     updateDisplay();
> >   }};
>
> > Finally, here is what my updateDisplay() method is doing:
>
> > private void updateDisplay() {
> >     if (csModel.getState() != Model_ContentSearch.State.RUNNING) {
> >         if(remindersList != null && remindersList.size() > 0){
> >                 r_adapter = new
> > ReminderAdapater(Activity_ContentSearch.this, remindersList,
> > thisListView);
> >                 thisListView.setAdapter(r_adapter);
> >                 r_adapter.notifyDataSetChanged();
> >         }
> >     }}
>
> > This works beautifully when I do this normally. However, if I change
> > the orientation while the long-running operation is running, it
> > doesn't work. It does make the callback properly, and the
> > remindersList does have items in it. But when it gets to this line:
>
> > r_adapter.notifyDataSetChanged();
> > Nothing happens. The odd thing is, if I do another submit and have it
> > run the whole process again (without changing orientation), it
> > actually updates the view twice, once for the previous submit and
> > again for the next. So the view updates once with the results of the
> > first submit, then again with the results of the second submit a
> > second later. So the adapater DID get the data, it just isn't
> > refreshing the view.
>
> > I know this has something to do with the orientation change, but I
> > can't for the life of me figure out why. Can anyone help? Or, can
> > anyone suggest an alternative method of handling threads with
> > orientation changes?
>
> > Bara

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