IntelliJ doesn't recognize java project after cloning
You have to mark your src directory as Source Root.
Right-click on the src folder and select Sources Root:
Then you'll see that the icons will change:
EDIT
Check the output path by bringing up the Project Structure view.
Press Ctrl+Alt+Shift+S
Similar to what maba said above, but if applicable you probably want to mark main and test as source & test source directories (respectively). That's a common project directory structure where literally marking src (parent of main and test) as source won't work for you.
Yes, marking src folder as 'Source Root' resolved the issue. Earlier intellij was not detecting java files.
Go to: Right Click --> src --> (Choose option) Mark Directory as --> Source Root.