app namespace not found in styles.xml in res folder

You can’t use an app namespace in your style file, and you should refer to style attribute wihtout app namespace in your layout.

You can do somenthing like this:

<android.support.v7.widget.Toolbar    
       xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:tools="http://schemas.android.com/tools"
        android:id="@+id/toolbar_show_addresses_simple"
        style="@style/toolbar_dark" >

Style:

<style name="toolbar_dark" parent="Widget.AppCompat.Toolbar">
    <item name="android:background">@color/green</item>
    <item name="popupTheme">@style/ThemeOverlay.AppCompat.Light</item>
    <item name="theme">@style/ThemeOverlay.AppCompat.Dark</item>
</style>