Error: Could not find or load main class main.java Caused by: java.lang.ClassNotFoundException: main.java

Question:
I continue to get the following error: “Error: Could not find or load main class main.java
Caused by: java.lang.ClassNotFoundException: main.java” everytime I run any program. I am trying to run something very simple just for informational and test purpose.
Please provide the simplest form of help while being very thorough without assumption that I understand all of this. I have searched for similar issues where people had this issue and i am unable to follow. If i need to change or adjust something please tell me exactly where
Current behavior:
I get Error: Could not find or load main class main.java
Caused by: java.lang.ClassNotFoundException: main.java

Desired behavior
Should print the statement

Repl link:

code snippet
// import static org.junit.jupiter.api.Assertions.assertEquals;

// import org.junit.jupiter.api.Test;

public class Main {
  public static void main(String[] args) {
    System.out.println("Hello world!");
  }

  // @Test
  // void addition() {
  //     assertEquals(2, 1 + 1);
  // }
}

Did you figure this out? I need help with this as well.