81 lines
3.4 KiB
Plaintext
81 lines
3.4 KiB
Plaintext
page.title=Binding to Data with AdapterView
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@jd:body
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<p>Some types of ViewGroup objects have a UI that is visible on the screen — {@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>
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<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>
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<p>AdapterView objects have two main responsibilities: </p>
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<ul>
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<li>Filling the layout with data
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</li>
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<li>Handling user selections
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</li>
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</ul>
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<p>The sections below describe how the AdapterView fulfills those responsibilities.</p>
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<h3>
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Filling the layout with data
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</h3>
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<p>This is typically done by binding the class to an {@link
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android.widget.Adapter} that gets its data from somewhere — either a list that
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the code supplies, or query results from the device's database. </p>
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<pre>
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// Get a Spinner and bind it to an ArrayAdapter that
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// references a String array.
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Spinner s1 = (Spinner) findViewById(R.id.spinner1);
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ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(
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this, R.array.colors, android.R.layout.simple_spinner_item);
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adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
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s1.setAdapter(adapter);
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// Load a Spinner and bind it to a data query.
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private static String[] PROJECTION = new String[] {
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People._ID, People.NAME
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};
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Spinner s2 = (Spinner) findViewById(R.id.spinner2);
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Cursor cur = managedQuery(People.CONTENT_URI, PROJECTION, null, null);
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SimpleCursorAdapter adapter2 = new SimpleCursorAdapter(this,
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android.R.layout.simple_spinner_item, // Use a template
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// that displays a
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// text view
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cur, // Give the cursor to the list adatper
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new String[] {People.NAME}, // Map the NAME column in the
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// people database to...
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new int[] {android.R.id.text1}); // The "text1" view defined in
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// the XML template
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adapter2.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
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s2.setAdapter(adapter2);
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</pre>
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<p>Note that it is necessary to have the People._ID column in projection used with CursorAdapter
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or else you will get an exception.</p>
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<h3>
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Handling user selections
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</h3>
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<p> This is done by setting the class's {@link
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android.widget.AdapterView.OnItemClickListener} member to a listener and
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catching the selection changes. </p>
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<pre>
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// Create a message handling object as an anonymous class.
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private OnItemClickListener mMessageClickedHandler = new OnItemClickListener() {
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public void onItemClick(AdapterView parent, View v, int position, long id)
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{
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// Display a messagebox.
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Toast.makeText(mContext,"You've got an event",Toast.LENGTH_SHORT).show();
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}
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};
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// Now hook into our object and set its onItemClickListener member
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// to our class handler object.
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mHistoryView = (ListView)findViewById(R.id.history);
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mHistoryView.setOnItemClickListener(mMessageClickedHandler);
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</pre>
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