Unlike previous version, the new API 23 comes with the
coordinatorLayout and stuff and just to make them simple to use android has distinguished activity’s layout into two different layout i.e.
I’ll explain what they are for:
this xml file is used to display
This xml file is use to display your stuff i.e. what you want to display to users.
So, if you are just asking in which xml you have to put your stuff,
content_main.xml is the one….