Such a list can be found in Android Market when the list of applications is progressively loaded from the network server. The problem is worth a simple test program to analyse because it clearly shows the power of the Android adapter concept.
Click here to download the test program.
Our test application does not actually connect to the network but simulates the slow data source. If you check the Datasource class, you will find that even though this "data source" is a simple array, the accessor method adds a 500 ms delay to every access. This simulates well the fact that loading from certain data sources takes time. The trick is in the PageAdapter class. This class adds a View to the end of the list ("Loading ..."). Android Market animates this view but the idea is the same. Whenever this View is drawn, the adapter kicks the loading thread which progressively fetches new elements from the data source, adds them to the Adapter's data set and notifies the adapter that the data set has changed. There is the usual fiddling with a Handler to make sure that notifyDataSetChanged() is invoked in the context of the UI thread. The Adapter constantly changes the value returned by the getCount() method as the items are loaded from the data source. When the whole data set is loaded, the "Loading ..." widget is not drawn anymore therefore nothing triggers the loading thread.
Here is how it looks like.
No, wait a minute, here is how it looks like.
Yes! After having blogged for more than 2 years about Android, I finally put my hands on an actual Android phone. The story is complicated but the essence is that a friend thought that I deserved that phone and gave it to me. Thanks for everyone involved!
11 comments:
Wow, congrats!
I couldn't agree more with your friend, you have deserved it!
cool man..
You need to check out all the commonsware stuff:
http://github.com/commonsguy/cwac-endless
I checked it out. :-)
Here is the result.
good tutorial but
i need progressive loading ListView for my custom list.
my list item consist of an icon and two text fields.
please share if anybody got any example for this?
genxsol, adapt this blog entry:
Custom widget adapters
Then update getView() in PageAdapter as shown by the custom widget adapter example.
Just a small info :-)
with eclipse and ddms.bat you can take snapshots of the current screen,of course u need the device to be hooked up with USB cable :-)
10x for the tutorial, i'm trying to figure out if a fellow worker's code is good or not (it's actually an expandable list).
10x Again.
Please! Somewhere in the process of taking that picture, transferring it to your computer and uploading it to your, you should have realized that it is a truly crappy photo!
http://www.ryangmattison.com/post/2011/08/22/Reverse-Paginated-List-View-(1-3).aspx
Robust Reusable Paginated ListView Tutorial
Hey,
Thanks for this great tutorial. I am following this rather than CW-Endless Adpater. But my data is not set on the listview. Rather it shows me Loading symbol only. Please help. Below is my getItem() method. Have been stuck for few days.
public HashMap getItem( int itemIndex ) {
// It's a slow data source
if(!requestparameter.equals(""))
new LoadAllAds().execute();
return productsList.get( itemIndex );
}
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