Reference color resource in TextView

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <color name="background_color">#aa0000</color>
</resources>

<?xml version="1.0" encoding="utf-8"?>

<TextView xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:background="@color/background_color"
    android:gravity="center"
    android:text="Hello World, MainActivity!" />