Q:

Android Studio shows every line of code with lint -compile- error

What the heck.   My app worked yesterday.   Today, every line of code has a lint error, including my imports.   Mostly "cannot resolve ...."
cannot resolve symbol TextView
cannot resolve symbol Intent
...
...

Weirdly, I can still run my program to an emulator and it seemingly works fine. 
This is what I tried. 

Cleaning project

Rebuilding project

Syncing project

Updating Android Studio

Restating Android studio

Closing project and reopening

Update:
i have this note in my layout preview

NOTE: This project contains Java compilation errors, which can cause rendering failures for custom views.  Fix compilation problems first. 

I really don't know how to start trouble shooting this issue
Update 2
I am dying here.   I reinstalled both Java and Android Studio.   I believe I have the path for JDK and SDK correct.   I tried a new project... wouldn't compile.. same thing.   I appreciate any advice.  
SOLUTION YEAH !! 
"File" -> "Invalidate Caches...", and select "Invalidate and Restart"

A:

I figured it out.   Whew! 
"File" -> "Invalidate Caches...", and select "Invalidate and Restart"

