R. java was modified manually! Reverting to generated version

After entering eclipse, the menu --> Project --> clean is equivalent to deleting the R file and then generating the R file automatically. If the R file is not automatically generated, there is an error in the program, which is generally a naming problem. I encountered the following situation: (1) control naming conflicts in different xml files in the layout folder (because I copied them directly ). Solution: the control name must be unique, that is, the control name of Chongming should be changed, and then the clean Project will automatically generate the R file. (2) The res folder can contain only corresponding folders, but cannot contain files or images. (3) All file names in the res folder must be in lowercase. The R file is automatically generated as long as the res file is not correct.