Error: Could not find or load main class in intelliJ IDE
This might help:
1) "Build" menu -> "Rebuild Project
".Sometimes Intellij doesn't rewrite the classes because they already exist, this way you ask Intellij to rewrite everything.
2) "Run" menu -> "Edit configuration
" -> delete the profile -> add back the profile ("Application" if it's a Java application), choose your main class from the "Main Class" dropdown menu.
3)"Build" menu -> "Rebuild Project
".
If none of the above answers worked for you, just close your IntelliJ IDE and remove the IntelliJ IDE file and folder from the root of your project:
rm -rf .idea *.iml
Then open the project with IntelliJ. It must work now.