title: "cannot resolve symbol R" in Android Studio
body: <p>In every instance in all of my classes where I reference <code>R.id.something</code>, the <code>R</code> is in red and it says "cannot resolve symbol R".  Also every time there is <code>R.layout.something</code> it is underlined in red and says "cannot resolve method setContentView(?)". The project always builds fine. It is annoying to see this all the time. I have read many other questions on here about something similar but most involved importing projects from Eclipse. I am using what I believe to be the most recent version of Android Studio and the project was created with Android Studio and worked without any "cannot resolve R" problems. I would like to know what causes this if anyone knows.</p>