Android Studio R file missing or error resolution method

In Android studio, sometimes references to resources can be lost or errors in R files, most of the time due to the introduction of resources when the R file is not updated timely caused by

(If the code has no errors or resource references without errors)

Note: The file name of the resource files must be lowercase, that is, the file name of the. xml file

Such as:

R file Error, Solution:

One: Recompile once

This method I tried once, but the effect is not very significant, because then when I again introduced the resources and then the error.

Two: Rebuild Project

Select Build--> Rebuild Project, select the lower

Wait for some time, after the completion

Android Studio R file missing or error resolution method