intellij icon over project files

Question

intellij has placed what look like no entry signs over my java files (red circles with a line through) searched around but cannot find why? Would anyone know please.

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Answer 1

It means those files aren't part of the project settings. How did you create that project?

I'm not sure which version of IntelliJ you're using - I run 9.0.1. I'd recommend opening the project structure (icon to the right of the "wrench" or Ctrl+Alt+Shift+S), click on "Modules", and designate the directory where the .java files are located as a source directory (it'll change to a blue color).