I make this call to a static singleton instance from the class GameManager.java
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HUD.getInstance().update(timeDelta);
HU
Thanks for the help so far, turns out the fix was to compile HUD.java first (right click on the file-> Compile HUD.java). After compiling the java file the rest of the project could be compiled without any problems.
I don't really know why this fixed it, or why IntelliJ wouldn't do this automatically, but root error seems it has to do with IntelliJ not correctly handling having multiple classes in a single .java file.