IntelliJ Code Completion not working for new Java classes

Question

IntelliJ IDEA 13 has started exhibiting a very weird behavior in my local setup.

Namely, in any new Java class added to an existing project

Answer 1

I am using IntelliJ Ultimate 2017.1, and I encountered similar issue. Maven project, was trying to using selenium APIs, but the intellisense didn't pop up relative methods for me.

Here is the way I solved my issue:

Right click on your project src folder
Choose Mark Directory As Then select Sources Root