Android Studio 2.1 Cannot resolve symbol 'R'

Question

Android Studio 2.1, Java V8 Update 91, Gradle 2.1.0 .

I know that this questions has been asked many times here, but none of the recommendation solutions works out.

Answer 1

Sometimes the R.java class is not created when there is some error into an xml file (like activity_main.xml). For example, if you change some attribute name that has a reserved word that cannot be changed. Like this: if you changed the attribute called: id to another name like
id_A_Word_With_Error_Here in this code that can be part of the activity_main.xml, your error (R class not created) can occur.

and there is an error like:

If clean, rebuild did not work and there is no error with import like import com.something... , my suggestion is to search an error into xml files.