When images are added to the Android project, the error cannot be resolved or is not a field is returned.

SDK and ADT are 22.6.2

Project 4.4.2

When I wrote the Android code today, I added several images to the project and used the R. drawable call in the Code. The error cannot be resolved or is not a field

Then I checked the R. in the java file, I found that the image resource id I added already exists. I think it is strange that the R. this occurs only when java files are created.

I checked the information on the Internet and did not find any solution to my problem. Then I checked my code from start to end and did not find any exceptions at first. Suddenly, when I looked at the code in the file header, I found a suspicious code import android. r; after I tried to delete this line of code, it turned out to be okay. Now I have not figured out why, but my problem has been solved. If anyone else knows, please let me know!