Android Training (AdapterView & Adapter)

1. AdapterView
& Adapters
Android Training
By Khaled Anaqwa

2. AdapterView



The AdapterView is a ViewGroup subclass
whose child Views are determined by an
Adapter that binds AdapterView object to
data of some type.
Typically you are going to use subsclasses of
AdapterView class instead of using it directly
Example subclasses of AdapterView class



ListView
Spinner
Gallery

3. Adapter
 You
can populate an AdapterView such
as ListView or GridView by binding the
AdapterView instance to an Adapter,
which retrieves data from an external
source and creates a View that
represents each data entry.

4. AdapterView & Adapters

5. So
 The
Adapter provides access to the data
items.
 The Adapter is also responsible for making
a View for each item in the data set.
 Types of Adatpers - they implements
ListAdatper interface



ArrayAdatper
CursorAdatper
There are a few more

6. Adapter Class Hierarchy
 BaseAdatper
abstract class implements
ListAdapter and SpinnerAdatper
interfaces
 ArrayAdapter and CursorAdapter classes
are subclasses of BaseAdapter class

7. AdapterView Responsibilities
 Two


main responsibilities of AdapterView
Filling the layout with data (with a help from
Adapter)
Handling user selections - when a user
selects an item, perform some action
 AdapterView.OnItemClickListener
 AdapterView.OnItemLongClickListener
 AdapterView.OnItemSelectedListener

8. ListActivity




Android-provided class specially designed for
displaying a list of items by binding to a data
source such as an array or Cursor, and exposes
event handlers when the user selects an item.
ListActivity hosts a ListView object that can be
bound through an adatper to different data
sources, typically either an array or a Cursor
holding query results.
setListAdapter(ListAdatper adapter) method
automatically creates ListView object from the
ListAdapter object
Has a default layout that consists of a single, fullscreen list in the center of the screen

9. Example
 List
of COUNTRIES

10.  Notice
that this does not load a layout file
for the Activity (which you usually do with
setContentView(int)).
 setListAdapter(ListAdapter) automatically
adds a ListView to fill the entire screen of
the ListActivity.

11. What is the difference
between a ListView and a
ScrollView ?

12. Simply
 ScrollView
a host for “static” content and
a ListView a host for “dynamic” content.

13. Listview
 ListView
is a view group that displays a list
of scrollable items. The list items are
automatically inserted to the list using an
Adapter that pulls content from a source
such as an array or database query and
converts each item result into a view
that's placed into the list.

14. Spinner
A
view that displays one child at a time
and lets the user pick among them.
 The items in the Spinner come from the
Adapter associated with this view.

15. Example
 Choose
one of COUNTRIES

16. In ArrayAdapter

Data updates



The ArrayAdapter class allows to remove all
elements in its underlying data structure with the
clear() method call.
You can then add new elements via the add()
method or a Collection via the addAll() method.
You can also directly modify the underlying data
structure and call the notifyDataSetChanged()
method on the adapter to notify him about the
changes in data.