I know there are several adapters to manipulate listviews like ArrayAdapter, BaseAdapter, CursorAdapter and so on, but I don't how to choose the best solution for my needs... I mean, when I'm choosing the adapter, which are the criterias that I should check before select the adapter to use?
Every kind of help will be appreciated!
The major concern in adapter selection is how you get your data to populate the list.
If the data is coming from a database/cursor, you should use one of the cursor adapters. You could use an array adapter, but that would just be unnecessary computational cycles to transfer the cursor data to the array before setting the adapter.
If your data is in an array then your obvious choice is one of the array adapter types.
If your data is coming from different sources, you'll need to create your own adapter or modify one of the existing ones.
After the incoming data format consideration might come thought on list modification and which adapter would work best with whatever needs you have to modify the list (and/or the data backing it).
Related
Should I use array adapter or base adapter or cursor adapter?
What do you use most? I found some code that uses base adapter for fragments. Can I use array adapter or cursoradapter for listfragments?
I know how to use listview in a simple way like using the android.r.simple. I want to know what I should use in creating a listview that uses listfragment and populating it with data that came from SQLite.
What is the easiest adapter to use to achieve this?
There are difference between the different adapter class. You should decide to use one depending on your model data.
ArrayAdapter is better if you have an ArrayList of objects.
CursorAdapter is better if you have a database query and a Cursor
BaseAdapter is the most customizable, so you can use it for anything (you have to customize it a little bit more than others)
I normally end up extending BaseAdapter. It's simple enough, and ArrayAdapter isn't flexible enough to handle the case where items have multiple values that need to go into different fields in your list item.
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.
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.
I need to implement a ListAdapter for multiple row types. So pick a layout per row based on the content of that row. I would like to hear some opinions on the merits of the different types of ListAdapters for accomplishing this. I don't expect to have thousands of rows or even a hundred, but I may potentially have quite a few different layouts and need a flexible easy to understand implementation.
So I am considering
BaseAdapter
ArrayAdapter
CursorAdapter
SimpleCursorAdapter
What are some of the advantages/disadvantages of these adapters. Would a cursor based adapter be better?
I want a it to be flexible, easy to change and work reliably.
The adapters are there to adapt a data source to the view, so it really comes down to your data source.
If its a database data source and you have largely straight-froward mappings of columns to text and image views, start with SimpleCursorAdapter.
If its a database data source but a lot of custom mappings or if you end up overriding a lot of SimpleCursorAdapter's functionality anyway, take a look at CursorAdapter.
If the data source is something that can viewed as an array, the look at ArrayAdapter.
If its a custom data source or if there's a alot of custom logic for binding the data to the views that doesn't fit the other adapters, derive your own adapter from BaseAdapter.
I am going to make a grid of images and I am trying to figure out whether to use an array adaptor or a baseadaptor. While the GridView example, stores the data in an array, it uses a BaseAdapter rather than a ArrayAdaptor. I am curious why this is. One thing I noticed about an ArrayAdapter, is that its constructor takes a textViewResourceId for some unknown reason - although the documentation say the getView can be used to make it work with other kinds of views as well. So, if I want a fixed grid of images for a menu, which class would you recommend choosing?
You typically choose your adapter class based on what the model data is. If you have an ArrayList of objects, use ArrayAdapter. If you have a Cursor from a database query, use a CursorAdapter. BaseAdapter can be used for anything, but it requires more coding, since it has no innate knowledge of how to iterate over the data.