I'm trying to use a listView with a divider and I was about to change divider's width so I looked in the web site and I found this solution :
When I tested in my app, I have no divider, but if I switch to use a simple color the divider appears again
This this my code :
my Activity layout :
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<TextView
    android:layout_width="match_parent"
    android:layout_height="80sp"
    android:elegantTextHeight="true"
    android:text="Paramètres"
    android:textSize="24sp"
    android:gravity="center"
    android:textColor="#ffffff"
    android:background="#191919"/>
<ListView
    android:id="@+id/list"
    android:layout_height="match_parent"
    android:layout_width="match_parent"
    android:dividerHeight="2dp"
    android:divider="@drawable/list_divider">
</ListView>
</LinearLayout>
list_divider.xml
<?xml version="1.0" encoding="UTF-8"?>
<inset xmlns:android="http://schemas.android.com/apk/res/android"
android:insetLeft="15dp"
android:insetRight="15dp" >
<shape
    android:shape="rectangle" >
    <stroke
        android:dashGap="1dp"
        android:dashWidth="1.5dip"
        android:width="2dp"
        android:color="#000000" />
    <size android:height="3dp"/>
</shape>
</inset>