docs/html/guide/topics/views/binding.jd

page.title=Binding to Data with AdapterView
@jd:body

<p>Some types of ViewGroup objects have a UI that is visible on the screen &mdash; {@link android.widget.AdapterView AdapterView} is one such object. AdapterView is a ViewGroup subclass whose child Views are determined by an {@link android.widget.Adapter Adapter} that binds to data of some type. AdapterView is useful whenever you need to display stored data (versus resource strings or drawables) in your layout.</p>

<p>{@link android.widget.Gallery Gallery}, {@link android.widget.ListView ListView}, and  {@link android.widget.Spinner Spinner} are examples of AdapterView subclasses that you can use to bind to a specific type of data and display it in a certain way. </p>


<p>AdapterView objects have two main responsibilities: </p>
<ul>
    <li>Filling the layout with data
    </li>
    <li>Handling user selections
    </li>
</ul>

<p>The sections below describe how the AdapterView fulfills those responsibilities.</p>

<h3>
    Filling the layout with data
</h3>

<p>This is typically done by binding the class to an {@link
android.widget.Adapter} that gets its data from somewhere &mdash; either a list that
the code supplies, or query results from the device's database. </p>

<pre>
// Get a Spinner and bind it to an ArrayAdapter that 
// references a String array.
Spinner s1 = (Spinner) findViewById(R.id.spinner1);
ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(
    this, R.array.colors, android.R.layout.simple_spinner_item);
adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
s1.setAdapter(adapter);

// Load a Spinner and bind it to a data query.
private static String[] PROJECTION = new String[] {
        People._ID, People.NAME
    };

Spinner s2 = (Spinner) findViewById(R.id.spinner2);
Cursor cur = managedQuery(People.CONTENT_URI, PROJECTION, null, null);
     
SimpleCursorAdapter adapter2 = new SimpleCursorAdapter(this,
    android.R.layout.simple_spinner_item, // Use a template
                                          // that displays a
                                          // text view
    cur, // Give the cursor to the list adatper
    new String[] {People.NAME}, // Map the NAME column in the
                                         // people database to...
    new int[] {android.R.id.text1}); // The "text1" view defined in
                                     // the XML template
					 
adapter2.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
s2.setAdapter(adapter2);
</pre>

<p>Note that it is necessary to have the People._ID column in projection used with CursorAdapter
or else you will get an exception.</p>
<h3>
    Handling user selections
</h3>
<p> This is done by setting the class's {@link
android.widget.AdapterView.OnItemClickListener} member to a listener and
catching the selection changes. </p>
<pre>
// Create a message handling object as an anonymous class.
private OnItemClickListener mMessageClickedHandler = new OnItemClickListener() {
    public void onItemClick(AdapterView parent, View v, int position, long id)
    {
        // Display a messagebox.
        Toast.makeText(mContext,"You've got an event",Toast.LENGTH_SHORT).show();
    }
};

// Now hook into our object and set its onItemClickListener member
// to our class handler object.
mHistoryView = (ListView)findViewById(R.id.history);
mHistoryView.setOnItemClickListener(mMessageClickedHandler); 
</pre>