Caused by: java.lang.RuntimeException: Binary XML file line #18: You must supply a layout_width attribute.

[Jameshuihui]

always prompt :Caused by: java.lang.RuntimeException: Binary XML file line #18: You must supply a layout_width attribute.

[whiteLT]

do this:

<style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
    <item name="expandableItemStyle">@style/ExpandableItemStyle</item>
</style>

<style name="ExpandableItemStyle">
    <item name="android:layout_height">@dimen/item_size</item>
    <item name="android:layout_width">@dimen/item_size</item>
    <item name="android:background">@drawable/bg_item_with_title</item>
    <item name="android:layout_margin">@dimen/item_margin</item>
    <item name="android:textColor">@color/gray</item>
    <item name="android:textSize">@dimen/item_text_size</item>
</style>

[pedrovgs]

Hi @whiteLT and @Jameshuihui sorry for the delay. As you've already found the issue I've sent a PR updating the project README.md with this information. #10