Fail to run Java code (by opening a project) with Intellij IDEA

Question

I am new to the IDE. I have installed Java SE Development Kit 13.0.1 and set it as my JDK installation.

I opened a project (.java file) and the code was successfully shown. But the main run is greyed out and I can't run my code.

May I know how can I solve it? Thanks for your help!

Answer 1

I think, your source folder is not specified as a source folder. To fix this, do the following:

Go to modules(in the Project Structure menu)

Select your source folder(likely src )

Click on source folder above it.

The source directory should be blue.

Save the changes(click ok to close it)

It should work.

Answer 2

I'm not so sure about that (its kind of a bug that sometimes happens), but try putting your mouse on the "main" in the main function and then hit ctrl + Enter and choose run.

hope this helps