Each time I check “Delegate IDE build/run actions to Maven,” my Scala program ends up like this.

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If it’s just a simple HelloWorld program and your pom.xml has nothing in it, then it’s odd that you encounter this issue.
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Then try unchecking “Delegate IDE build/run actions to Maven” and see if that resolves the issue.

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Program runs normally.
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My Scala version is 2.11.8, and JDK version is 1.8.181.
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Although I’ve double-checked the JDK and Scala SDK in the Project Structure multiple times, I’m still concerned about unchecking “Delegate IDE build/run actions to Maven” because I might need to use Maven for packaging in the future.

I hope my expertise has been helpful! If you have any further questions or need clarification, feel free to ask.