Intellij Cannot resolve symbol on import

This problem happens intermittently for different libraries and different projects. When trying to import a library, the package will be recognized, but the class name can't be resolved.

If on the import statement, I right-click -> Goto -> the package's declaration, I see all the decompiled classes displayed in the side pane -- Including the ones I need -- If I try to auto-complete the import statement, I notice the class I need is not featured in the dropdown.

I tried invalidating caches already, doesn't work. I cannot find any class conflicts -- there is no other jar file in my classpath with the same package name. I am able to import this class into other projects.

Please see screen shots:

Anyone have a clue?

Solution 1:

You can try invalidating the cache and restarting IntelliJ, in many cases it will help.

File -> Invalidate Caches/Restart

Solution 2:

There can be multiple reasons for this. In my case it was wrong source root issue. Invalidate caches didn't work along with other solutions.

Check your module source roots.

1. Project Structure (Ctrl+Alt+Shift+S).

2. Modules

3. Select your problem module.

4. Change tab on top of window "Sources".

5. Remove unwanted source roots. Keep one and add src and test source roots in this root.

Solution 3:

File -> Invalidate Caches/Restart And Build your project

Solution 4:

IntelliJ has issues in resolving the dependencies. Try the following:

1. Right click on pom.xml -> Maven -> Reimport
2. Again Right click on pom.xml -> Maven -> Generate sources and update folders

Solution 5:

Run this command in your project console:

mvn idea:idea

Done. Had this issue many times. Tried 'Invalidate Cache & Restart' and all other solutions. Running that command works perfect to me. I'm currently using IntelliJ 2019.2, but this also happened in previous versions and solution worked as well.