You return an object that doesn't hold any permanent residence to an
activity, just a temporary one.
private final Runnable mUpdateDisplayRunnable = new Runnable() {
public void run() {
mData.getCurrentActivity().updateDisplay();
}
};
public void onCreate(...) {
...
mData = (MyRetainedData)getLastNonConfigurationInstance();
if (mData == null) {
mData = new MyRetainedData();
...
...
}
mData.setCurrentActivity(this);
...
}
public void onDestroy() {
...
// don't hold on to activity about to be destroyed
mData.setCurrentActivity(null);
..
}
public Object onRetainNonConfigurationInstance() {
return mData;
}
The trick here is that the field mData in the destroyed Activity and
the newly created Activity point to the exact same instance of
MyRetainedData. This instance almost acts like a static/global
variable
And if you would be using AsyncTasks in your app, you can put
references to those in the MyRetainedData to hold on to them when
changing configurations. Or you could stuff other stateful data in
there that needs to survive config-changes.
On Jun 21, 11:30 pm, Bara <[email protected]> wrote:
> 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 <[email protected]> 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 <[email protected]> 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- Hide quoted text -
>
> - Show quoted text -
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