Develop Reference

Using TreeSets for ArrayAdapters Equivalent instead of ArrayLists

Because ArrayLists are not particularly efficient, I would like to use a TreeSet in my Android App that will add items, and display them in alphanumeric order. Is there anything similar to an ArrayAdapter that I could use in order to more efficiently display the items within the TreeSet to the user?
Thanks for your help!

You can use whichever data structure you'd like by extending BaseAdapter. By extending BaseAdapter you can override the getView method and pass the correctly formatted view using your TreeSet as the data structure. This post shows a nice example of a BaseAdapter implementation, now they are using a List still but you can easily see how to implement the same thing using a TreeSet.

Append items to Simple Adapter dynamically

I have a very simple question. I'm working on an Android application where I make use of Simple Adapter for ListView. Now I need to append items to this ListView dynamically. I know it is possible to do so in case of Array Adapters.
It is done as follows:
adapter.notifyDataSetChanged();
Is there any equivalent for the same in case of Simple Adapters? I couldn't find much relevant links regarding this on the net.
Kindly help.
Thanks in advance!

I think not, but you always can create a new SimpleAdapter and call setAdapter again with the new adapter.
If you are going to add/remove elements you, probably, need some other adapter not a SimpleAdapter. Because they say in the docs that SimpleAdapter is 'An easy adapter to map static data to views defined in an XML file'

Advice with ArrayAdpters

Can anyone tell me what exactly does an array adapter do? I've tried searching the net but all I get is code examples. Please explain me what it does, I've visited the android developers as well.

An ArrayAdapter can be used as a data source for a number of different Android Views, such as a ListView or a Spinner.
Basically, you pass some kind of array or list to the constructor of an ArrayAdapter. Then, the adapter can be hooked up to a ListView by calling setAdapter(). You can also use the add and remove methods of the adapter to modify the underlying list itself.
You can also use an ArrayAdapter to customize the appearance of items in a ListView for example (or other Views) by using the constructor and passing in the resource of a layout to use, or by overriding the getView() method and building it yourself.

Typically, an adapter is some kind of translator. It's the "man in the middle" who know how to dialog with both sides and convert what is said.
An arrayAdapter is a class which get datas from an array and format it for a listview or spinner to understand it. When a listview need the data 4, for example, it will ask the adapter who will return him the 4 element of the array.
Ok, the listview could directly use the array.But with the adapter you're allowed to use any kind of data source. An ArrayAdapter(subclass of adapter) uses an Array, but another adapter could use a database or a file or anything else.That way the listview is able to get datas directly from any source without knowing how to access it.That is the adapter's role.

Android Scrolling Autogrow ListView

Hello
I am trying to build a listview based on content from the web.
I have had a look at :
http://androidboss.com/load-listview-in-background-asynctask/
example but it uses a predefined array of months. How can I substitute the known
array of months for an unknown undetermined number of items from the internet?
I want to load a listview with some data from the internet, the user
scrolls the list and it retrieves the next row(s) from the internet etc etc
rather than using a array of predetermined length.
Thanks Ian

You can use my EndlessAdapter for that. The project has a demo/ subproject demonstrating its use.

It sounds like you need to extend an adapter such as ArrayAdapter. Extending an ArrayAdapter so that you can dynamically generate the rows or alter the number of rows, and also notify the Adapter that the underlying data has changed, is a very common exercise in Android.
You'll find quite a few tutorials on this but, very basically, if you implement your own adapter by extending ArrayAdapter you can override getView() to programmatically generate each view, and you can override getCount() to provide the number of rows. You can use notifyDataSetChanged() to trigger a refresh of the list on the screen if some data has changed and you need to refresh.

How to setup a ListView that get its data from a server

I've been trying to find a tutorial of how to create a ListView that get its data from a server dynamically as it's scrolled. I have not been able to find complete documents of how to do this. Only small examples or ListView tutorials that deals with set arrays. This has left me where I don't know where to start building the ListView code.
I have some code that gets data from the server. I also do have all the layouts and basic Activity code.
How/what do ListView do to get one more rows as it is scrolled?
And when I need to have different row layouts. How do ListView handles this?
Is there a complete tutorial that deals with ListView and getting data from a server?

How/what do ListView do to get one more rows as it is scrolled?
There is nothing built into Android for this. You could use my EndlessAdapter, either directly or as an idea of how to accomplish similar ends in your own code.
And when I need to have different row layouts. How do ListView handles this?
You need to implement an appropriate ListAdapter, one that has proper implementations of getViewTypeCount() and getItemViewType().
Is there a complete tutorial that deals with ListView and getting data from a server?
Along with your other two bullets? Probably not. Your requirements are individually uncommon and are even less common in conjunction.