list_item.xml

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">

    <!-- selected. This style will be applied when the view is selected -->
    <item android:state_selected="true">
        <shape>
            <corners android:radius="12dp" />
            <solid android:color="@android:color/black" />
        </shape>
    </item>

    <!-- default -->
    <item>
        <shape>
            <corners android:radius="12dp" />
            <solid android:color="@android:color/white" />
        </shape>
    </item>

</selector>