Error in all the classes files: R cannot be resolved

Question

Example code:

setContentView(R.layout.main);

Error:

R cannot be resolved

There\'s this error in all the class

Answer 1

Check if your R is generated properly inside the "gen" folder.Check if there are any libraries missing which are added as dependencies from project properties. Also make sure that there are no issues which is preventing the app from generating R file. Go to Window > Show view> Problems and it will show you whats missing.