java.lang.RuntimeException: Uncompilable source code - what can cause this?

Question

This error is just bizarre, my code compiles fine, I can see there are no problems with it, yet this error has just popped up. I have tried re-starting NetBeans and there is

Answer 1

Disable Deploy on Save in the Project's Properties/Run screen. That's what worked for me finally. Why the hell NetBeans screws this up is beyond me.

Note: I was able to compile the file it was complaining about using right-click in NetBeans. Apparently it wasn't really compiling it when I used Build & Compile since that gave no errors at all. But then after that, the errors just moved to another java class file. I couldn't compile then since it was grayed out. I also tried deleting the build and dist directories in my NetBeans project files but that didn't help either.