在热切，得到的答案是，因为这在值-大/ refs.xml

After much looking, the answer is because of this in values-large/refs.xml

<resources>
    <item type="layout" name="activity_item_list">@layout/activity_item_twopane</item>
</resources>

它重定向为正常布局到一个更大的布局（双窗格版）其中， R.id.item_detail_container 定义的要求。

这是pretty的混淆。我不知道为什么他们不只是叫大布局一样的正常布局，但随后有不同的XML。

This is pretty obfuscated. I'm not sure why they didn't just call the large layout the same as the normal layout but then have different xml.