When IDEA opens an existing project chapter 3, in the project mode on the left side of idea, there is no project button on the left side, as shown in the screenshot of the problem below: (ps: the project structure can be displayed, but directories such as src are missing)
I checked some methods online:
1. Solution
Method 1: Find the error location and fix it.
Method 2: Clear the configuration and re-import it.
1) Close and restart IDEA (note that it is not to close the project, but to clear the memory and restart idea)
2) Delete the .idea folder under the project folder
3) Re-open the project with the IDEA tool
None of these methods worked for me, so here is the second solution:
There is a directory for the entire project under the project in the idea above.