Material Design Support Library中NavigationView添加下划线

<menu xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
tools:context=".MainActivity">

<group android:id="@+id/grp1">
<item
android:id="@+id/navigation_item_1"
android:checked="true"
android:icon="@drawable/ic_home"
android:title="@string/navigation_item_1" />
</group>

<group android:id="@+id/grp2">
<item
android:id="@+id/navigation_item_2"
android:icon="@drawable/ic_home"
android:title="@string/navigation_item_2" />
</group>
</menu>