I have created custom listview with baseadapter.
it's working fine.
but I am calculating total amout when adatper is filliup via getview method.
My question is when I can find that adapter has completed his process of filling up listview?
When adapter called getview() method for last the record after that I want to broadcast message. How can I do?
Thanks.
Adapter does not fill listview completely. It will only fill views that are on the screen ( it also depends on framework cos companies like Samsung, Sony do change the android framework a lot)
The best you should do is call Notifydatasetchanged on adapter and then handle call after that.
Views and whatever adapter needs to call should be done by then
Can you please explain more what you want to achieve. You probably need to use the adapter data and not think about touching its UI part?
Related
I'd like to change my listView items dynamically. The algorithm goes like this:
1.I create the default view for my listView using adapter and show it to user. The list item contains Imageview, textview and another imageview which is invisible.
2.The data is beeing dowloaded in the meantime.
3. after my data is downloaded, I'd like to check whether my listview contains any of downloaded items. If yes, I want to make visible the previously invisible ImageView for this item.
Should I add some kind of method to my adapter, call it and then call invalidateViews(), notifyDataSetChanged(), or notifyDataSetInvalidated()? Or maybe there is some kind of standard way to find my adapter's item by Id or sth and then make visible the imageview for this item?
This list update operation is the only one left to implement for me.
Should I add some kind of method to my adapter, call it and then call invalidateViews(), notifyDataSetChanged(), or notifyDataSetInvalidated()?
Yes, exactly.
maybe there is some kind of standard way to find my adapter's item by Id or sth and then make visible the imageview for this item?
Above mentioned way is enough. There is no such standard or special way to do it AFAIK.
Read the Displaying Bitmaps Efficiently introduction and in particular the part about Handle Concurrency. This will give you all the information you need.
I'm an Android beginner starting with fragments. My problem is the following.
I has a fragment that used to show a custom listview (it extended SherlockListFragment). I populated the listview with some data server. The action of retrieveing data of the server was executed in another thread and I had a handler to manage responses. In this handler (inside my fragment) I recovered data for my adapter and the I reloaded my adapter like this ((myAdapter) fragment.getListAdapter()).dataChange(); .
Well, now I wanted to convert the list in a custom grid cause I think it's much better for my app. So, the fragment doesn't extends SherlockListFragment, but BaseFragment. As I don't have a ListView anymore, I can't not use "getListAdapter.datachange()". Does anybody know the correct way to do this?
Thanks in advance.
Make an Adapter for the gridview that extends from BaseAdapter, or use an Adapter that extends from BaseAdapter.
then call notifyDataSetChanged on that adapter when the contents of your collection has changed.
Small example of adapter and grid
I would recommend making your changes on the Adapter, not the Grid (or list). Depending on the type of adapter you are using there are a couple different approaches.
ArrayAdapter
For an ArrayAdapter, using the standard modification methods (add, addAll, clear, remove) should update any views.
CursorAdapter
A CursorAdapter works in much the same way, except that you use either swapCursor or changeCursor to change the underlying data. That should notify all data set observers that the underlying data has changed.
All Adapters
If your observers don't get notified, usually because setNotifyOnChange was called, you can call mAdapter.notifyDataSetChanged() to manually update all listeners (UI views, services, etc.) that the underlying data has changed.
thanks a lot for your quick responses. I tried your ideas but finally I converted my old list in a grid by making a two columns' row. It was the best option to keep my header and footer on.
Instead of creating multiple activities, I would like to change the ArrayAdapter of the ListView as needed. I don't see any mention in the API about whether or not it is okay to call setAdapter() more than once.
To be more specific, say I would like to start an activity that has a ListView. In this example, the ListView is initialized with a listView.setAdapter(this) from, say, a CategoryArrayAdapter.
Then a user selects a category. Without starting a new activity, the code will set a new adapter for the same ListView. The new adapter, say ItemArrayAdapter calls listView.setAdapter(this).
Does someone have experience having done this successfully or know of a specific reason why this shouldn't be done?
I don't see any mention in the API about whether or not it is okay to call setAdapter() more than once.
The simple answer is YES, and I have done similar sort of things before.
This is exactly the reason why Adapter is existed and provided in the API. The actual content (Model) and how it is rendered (View) for each list items is isolated and implemented inside android.widget.Adapter, instead of directly bound to android.widget.AdapterView. As long as your adapter is properly implemented, you can swap/change the actual underlying adapter that bound to the ListView, simply by calling the setAdapter() method.
Resetting the adapter is ok, but notice, that there might be a GUI glitch when doing so, as the view whose adapter is being changed has to be redrawn with the new data. Aside from this you should be fine.
I am trying to get a button to show up on my list item (declared as android:visibility:"gone" in the XML) to show as visible when I perform some gestures on it. However, how can I actually notify the getView method correctly to display the button only on the listview item?
I tried using getChildAt(position) which ended up displaying several buttons at once.
I tried passing in the position for example I detected that the gesture was performed on from pointToPosition and passed it into the adapter for the getView method to display, but it had the same problem of displaying several at once.
do anyone know how can I solve this?
I think you may have a misunderstanding of how Adapter.getView() works its meant to create or reuse layouts when rendering the ListView it also needs to be fast so conditional manipulation in this method is discouraged. Although ListView.getChildAt() may work it does not effectively use the API. Your adapter will have a setViewBinder() unless you're using an ArrayAdapter (if so I suggest using SimpleAdapter because of the additional features). Use your ViewBinder implementation to switch the visibility of the button.
If you'd prefer to continue to use ArrayAdapter use ListView.getChildAt(int) to findViewById(R.id.your_button).setVisibility(). If this is what you already tried and its setting all the buttons visible then please post the related code.
I am trying to update the ListView with periodic updates taken from an HTTP response. Now, I am thinking that because this is very specific to my application, I can get away by using a background thread and then updating the ListView using the magic UI thread. The last time I tried this, I had to remove the entire adapter of the ListView and then fill it up again so it worked. But this time, what I am trying to do is a more "smooth" scrolling ListView... something like a scrolling ticker... Is there a different approach to achieve this?
That depends on the Adapter. If you are using an ArrayAdapter, you can call add() on the ArrayAdapter itself to add items on the fly.