Intellij Cannot resolve symbol on import

Question

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\'

Answer 1

I found the source cause!

In my case, I add a jar file include some java source file, but I think the java source is bad, in Intellij Idea dependency library it add the source automatic, so in Editor the import is BAD， JUST remove the source code in "Project Structure" -> "Library", it works for me.