How to set group divider color for ExpandableListView

Question

I can set the devider color for the children using childDivider attribute (black in this example). But, I don't see any way to set the color of the divider between the collapsed groups. System seems to be showing a 1px white line.

Solution 1

The color of the divider line when a group is closed can be set via:

android:divider

The color of the divider lines when a group is opened aka. the child is visible can be set via:

android:childDivider

Solution 2

For Group:

<item name="android:groupIndicator">@android:drawable/expander_group</item>

For Children:

<item name="android:childDivider">@android:drawable/divider_horizontal_dark_opaque</item>

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All the ExpandableListView traits:

<style name="Widget.ExpandableListView" parent="Widget.ListView">
    <item name="android:groupIndicator">@android:drawable/expander_group</item>
    <item name="android:indicatorLeft">?android:attr/expandableListPreferredItemIndicatorLeft</item>
    <item name="android:indicatorRight">?android:attr/expandableListPreferredItemIndicatorRight</item>
    <item name="android:childDivider">@android:drawable/divider_horizontal_dark_opaque</item>
</style>

<style name="Widget.ExpandableListView.White">
    <item name="android:childDivider">@android:drawable/divider_horizontal_bright_opaque</item>
</style>