I did some researches about this question but I couldn't find my answer. So, yes I did create a folder under res called "layout-land" and I put a separate main.xml in it. I intentionally deleted some images in the main.xml in the layout-land and I noticed that these images were still there when I rotated the android phone to horizontal.
Many questions similar to mine are caused by adding onConfigurationChanged to manifest. But I did NOT add anything to manifest as explained by this link
layout-land xml files does not work with onConfigurationChanged call back