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It's great that we've reduced some of
the code related to styling our views.

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But we still haven't made our managers
happy by allowing our app to be run on

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devices all the way back to KitKat.

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Let's make our first
attempt at fixing that.

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I'm in the apps build back creative file
where I'll change the minSdkVersion to 19,

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which corresponds to Android 4.4 KitKat.

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Let's sync Gradle and run the app on our
emulator with KitKat to see what happens.

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Well, the toolbar shouldn't be there but

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everything else looks good in the album
list activity and album details activity.

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What about in the play back activity?

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Whoops, there's a crash.

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Turns out that there's an image view
that's attempting to use a resource that

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isn't available on versions of
Android before Lollipop or API 21.

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I'll show you how to fix that crash and

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other issues of backwards
compatibility now.

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First, we need to grab the Android
support library called AppCompat

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that I mentioned earlier.

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To get the most recent
version of AppCompat,

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just perform a Google search for
support library packages Android.

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Click the link titled
Support Library Packages and

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then click v7 AppCompat
library from the sidebar.

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The most recent version
will be listed below.

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Copy that and paste it into your app's
build.gradle file along with a compile

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statement and some single quotes.

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Then when Gradle ask you to sync,
go ahead and do so.

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Now that we've added AppCompat,

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we can begin to fix the errors that
were plaguing our application.

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The first change we'll make is removing
the android:namespace declaration

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from the android:background attribute

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of the image view in our song playback
activity layout that is causing the crash.

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The reason the crash was happening here is
that on Android version 19, Android can't

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find the resource specified by
?:attr/SelectableItemBackgroundBorderless.

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That resource simply wasn't
available back at that time, so

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by removing the add Android we tell
the system to look up this value,

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selectableItemBackgroundBorderless, within
the current theme.

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In our case, since we're now going to be
using AppCompat, the system can find that

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resource and we're good to
continue our hunt for errors.

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Let's check and fix any issues
with our styles.xml file first.

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When we first look at this file, we'll
see that there's some red error markers.

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However, I wanna drive home
this point a little further.

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So bear with me as I perform
a quick little hack to bring these

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errors into more focus.

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In order to see more obviously what
attributes were available in KitKat,

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the version that we're targeting,

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I'm gonna go into my app's
build.grade file again and

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temporarily change the compileSdkVersion
to 19 to match my minSdkVersion.

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Now I'll go back into styles.xml and
sync the Gradle files.

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If you're following along and
you get an error message about failing to

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find target with hashstring Android 19,
just click Install Missing Platforms and

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Sync Project and
Android Studio will do the rest.

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After verifying you have the older
version of the Android SDK installed and

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successfully synced Gradle, a bunch of
errors will pop up and that makes sense.

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We just told Android to use an older
version of the platform so it can't find

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the resources it needs for the material
theme that's currently applied to our app.

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It's safe to ignore these errors for now,
though, as we're only temporarily lowering

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the compile list decay to perform
some maintenance for the app.

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When I synced my Gradle files,
a file called

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ldltr-v21/values/ltltr-v21.xml pops up,
and I get an error message.

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It's safe to close the file and
navigate back to the styles.xml file now.

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Now the errors in the styles.xml file
are lit up like a Christmas tree and

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they are much easier to spot.

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What we are going to do now is replace
the previous attributes from the Android

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platform with the attributes
from the AppCompat library.

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First, we will change the theme to inherit
from theme.appcompat.NoActionBar for

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both the app theme and the settings theme.

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To select the next occurrence of
the highlighted text, click Ctrl+G.

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I find that's an incredibly
useful trick in any IDE.

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Then we'll need to change
android:colorAccent,

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which sets the accent color for
the android:theme.material themes,

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to set the accent color for
the Theme.AppCompat themes by removing

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the android:namespace before
the words colorAccent.

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You may notice that we
still use the @android for

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setting the color itself to
@android:color/darker_gray.

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We can do this because the color darker
gray still exists on the platform on older

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versions.

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However, it's the color accent property
that did not exist back on API 19.

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Next we'll remove the android:
in our playback button style,

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as well as in our settings toolbar style,
and that should do it for our styles file.

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It is now backwards compatible.

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However, there is still some work
to do to complete the process.