ONGOING DEV

Our purpose is to create a very simple layout with a ListView that looks like a chat. Something like this: It is very easy. Let's take a common ListView in a RelativeLayout. Let's populate a simple Adapter, and run it. public class MainActivity extends ListActivity { private ViewHolderAdapter mAdapter; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); mAdapter = ListHelper.buildViewHolderAdapter(this, R.layout.list_item); setListAdapter(mAdapter); } } This is still not what we wuold like to achieve. Now we'll add an xml attribute to ListView: android:stackFromBottom="true" . In this way the ListView stacks its content from the bottom. We'll optimize the scroll with another xml attribute : android:transcriptMode="alwaysScroll" In this way the list will automatic...

All android devs use extensively ListView in their apps. I think many of us, also myself of course, have written at least once a very bad Adapter. I think that the first time there was talked about performance and optimization of listview, was at I/O 2009. You can find this document . At Google IO 2010,the subject was taken up again. Here you can find the document . There are 2 key points: View recycling View Holder pattern I would say that many of Android examples that I see do the first item properly. It's pretty simple, use the convertView on simple adapters like ArrayAdapter or use the newView on more involved adapters like CursorAdapter . But I must say that the ViewHolder pattern is not so common . It is very important to understand what it is, and why we should use view recycicling and ViewHolder pattern. Let's take a small example. It is a BAD ADAPTER . You should never do it!! /** * Bad Adapter. * * DON'T USE IT !!!!! * */ public class ...