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We just finished creating our loader,
but we still haven't seen how to use it.

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But before we get to that,

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it looks like I forgot to delete
this percentProgress line.

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So let's do that.

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Okay, now it's time to get back
to deleting our AsyncTaskClass.

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Over in MainActivity, let's start
by deleting our AsyncTaskClass.

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And let's also delete this
new MyAsyncTask line.

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Next, we need to implement a few callbacks
to help us interact with our loader.

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Specifically, we need to
implement LoaderCallbacks, and

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make sure we're picking the option
from the support library.

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And let's use a bitmap array for
our type parameter again.

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Then let's use Alt+Enter to implement
the three required methods.

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The first method is onCreateLoader.

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In this method, we need to create a new
instance of our loader and return it.

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So since our loader requires
a URL as a parameter,

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let's first cut and paste the URL
code into the top of this method.

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Then, right below the URL,
let's return a new instance of our loader.

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return new MyAsyncTaskLoader, and

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passing in this for
the context and url for the URL.

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I'd love to get rid of this
return null as well, but

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even though our URL isn't malformed,
we've still gotta catch the exception,

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which means we need to
have a return down here.

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Well.
Moving on to onLoadFinished,

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this method is called when your work is
done and is where we should update the UI.

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So let's first update the data,
our adapter is based on.

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myAdapter.bitmaps = data.

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And then let's notify our adapter
that the data has been updated.

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myAdapter.notifyDataSetChanged.

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Nice.

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The last method is onLoaderReset.

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If your loader's been reset,
then it no longer contains any data.

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So if you've got any references
to data in your loader,

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you'd want to clean
those up in this method.

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Since we don't have any way to reset our
loader, we're fine leaving this empty.

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Now that we've implemented
our loader callbacks,

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all that's left is to start our loader.

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At the bottom of onCreate.

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Let's call
getSupportLoaderManager().initLoader().

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Then let's pass in an arbitrary number for
the ID, I'll choose 1.

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And an arguments bundle, which we don't
have, so let's just pass in null.

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And finally a LoaderCallbacks object,

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which we've implemented
right here in this activity.

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So let's just pass in this.

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And before we forget, let's make sure to
show our progress bar while we're loading

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and hide it once we're done.

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So at the top of OnCreateLoader,

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let's add progressBar.setVisibility
to View.VISIBLE.

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And then at the top of onLoadFinished,
Let's set it to gone.

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progressBar.setVisibility(View.GONE); All
right, time for the moment of truth.

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Let's run the app and see what happens.

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There's our progress bar, and
now we've got our images.

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And if we rotate the app,
Awesome, it's the same images!

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So instead of re-downloading all of those
images, we just used our cached images and

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made for a much better user experience.

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When you've gotta do something
in the background and

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you're worried about the activity
lifecycle, just use a loader.

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Since a loader will stay alive
through a rotation, it's a great

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place to do your loading and keep any data
safe from being destroyed in an activity.

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If you'd like to learn more about loaders,
check out the teacher's notes below.

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And as always, if you've got any questions
or would like to try your hand at

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answering someone else's question,
be sure to check out the community.

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Until next time.