This is an extremely basic question and I'm embarrassed I haven't been able to find the solution online.

I would like to be able to update the text of my button in code. I am using the new Android Studio IDE. I created a blank activity when starting the project and placed a `Button` in activity\_main.xml. How do I access this button in code to change its properties? I am trying in the mainactivity.java file but the intellisense isn't giving me anything that looks promising.