Using the menu in an activity that extends the AppCompact it is necessary import the app context in the XML and use it:
<menu xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto">
<!-- "Mark Favorite", should appear as action button if possible -->
<item
android:id="@+id/action_favorite"
android:icon="@drawable/ic_favorite_black_48dp"
android:title="@string/action_favorite"
app:showAsAction="ifRoom"/>
<!-- Settings, should always be in the overflow -->
<item android:id="@+id/action_settings"
android:title="@string/action_settings"
app:showAsAction="never"/>
</menu>
What you need to do basically is add xmlns:app="http://schemas.android.com/apk/res-auto"
to the menu element in yout XML and use the showAsAction in the following format: app:showAsAction="ifRoom"
.
This will show the icon in the action bar, if possible.