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page.title=Loading Data in the Background
trainingnavtop=true
startpage=true
@jd:body
<div id="tb-wrapper">
<div id="tb">
<!-- Required platform, tools, add-ons, devices, knowledge, etc. -->
<h2>Dependencies and prerequisites</h2>
<h3>Dependencies</h3>
<ul>
<li>
Android 1.6 or later
</li>
</ul>
<h3>Prerequisites</h3>
<ul>
<li>
<a href="{@docRoot}training/basics/firstapp/index.html">Building Your First App</a> class
</li>
<li>
<a href="{@docRoot}training/basics/activity-lifecycle/index.html">
Managing the Activity Lifecycle</a> class
</li>
</ul>
<!-- related docs (NOT javadocs) -->
<h2>You should also read</h2>
<ul>
<li>
<a href="{@docRoot}guide/components/loaders.html">Loaders</a>
</li>
<li>
<a href="{@docRoot}guide/topics/data/data-storage.html#db">Using Databases</a>
</li>
<li>
<a href="{@docRoot}guide/topics/providers/content-provider-basics.html">Content Provider Basics</a>
</li>
</ul>
</div>
</div>
<p>
A {@link android.support.v4.content.CursorLoader} runs a query against a
{@link android.content.ContentProvider} on a background thread and returns a
{@link android.database.Cursor} to the main thread.
</p>
<p>
{@link android.support.v4.content.CursorLoader} has these advantages over alternate ways of
running a query:
</p>
<dl>
<dt>
Query on a background thread
</dt>
<dd>
A {@link android.support.v4.content.CursorLoader} query runs asynchronously on a
background thread, so it doesn't cause "Application Not Responding" (ANR) errors on the UI
thread. {@link android.support.v4.content.CursorLoader} creates and starts the
background thread; all you have to do is initialize the loader framework and handle the
results of the query.
</dd>
<dt>
Automatic re-query
</dt>
<dd>
A {@link android.support.v4.content.CursorLoader} automatically runs a new query when
the loader framework detects that the data underlying the {@link android.database.Cursor}
has changed.
</dd>
<dt>
Simple API
</dt>
<dd>
The {@link android.support.v4.content.CursorLoader} API provides the
query framework and cursor monitoring that you would have to define yourself if you used
{@link android.os.AsyncTask}.
</dd>
</dl>
<p>
A {@link android.support.v4.content.CursorLoader} is limited in that the query must be
against a {@link android.net.Uri} and must return a {@link android.database.Cursor}. Because of
this, a {@link android.support.v4.content.CursorLoader} can only run a query against a
{@link android.content.ContentProvider}.
</p>
<p>
This class describes how to define and use a {@link android.support.v4.content.CursorLoader}.
Examples in this class use the {@link android.support.v4 v4 support library} versions of
classes, which support platforms starting with Android 1.6.
</p>
<h2>Lessons</h2>
<dl>
<dt>
<strong><a href="setup-loader.html">Setting Up the Loader</a></strong>
</dt>
<dd>
Learn how to set up an {@link android.app.Activity} that inherits the necessary classes
for running a {@link android.support.v4.content.CursorLoader} and returning results.
</dd>
<dt>
<strong><a href="define-launch-query.html">Defining and Launching the Query</a></strong>
</dt>
<dd>
Learn how to perform a query against a {@link android.content.ContentProvider} using
a {@link android.support.v4.content.CursorLoader}.
</dd>
<dt>
<strong>
<a href="handle-results.html">Handling the Results</a>
</strong>
</dt>
<dd>
Learn how to handle the {@link android.database.Cursor} returned from the query, and how
to remove references to the current {@link android.database.Cursor} when the loader
framework re-sets the {@link android.support.v4.content.CursorLoader}.
</dd>
</dl>
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