Why doesn't Android Studio see R?

Question

Java

I am a novice programmer, I am writing a program, and then Android Studio tells me that it does not know Class R. I would like to know how to fix this error. Before that, I didn’t rummage through the code at all, I just made markup, when it came to the code, I noticed this error , which will be on the screen.

Answer 1

import your_package_name_from_manifest.R
or press Alt+Enter, it will find everything by itself