Why so red? IntelliJ seems to think every declaration/method cannot be found/resolved

Question

I just installed and re-installed IntelliJ. Every Java file is coming up RED. I checked the JDK; it is at 1.6.##. The maven clean install build worked just fine

Answer 1

I could not get any of these solutions to work for me. I had to manually go to every method/class that I got the error on and import it manually. After that everything was fine.

Answer 2

I have IntelliJ IDEA 12.x on the Mac and I use Maven 3 and I get the red highlighting over my code even though the Maven build is fine. None of the above (re-indexing, force import, etc.) worked for me. I had to do the following:

Intellij -> Preferences -> Maven -> Importing
    [ ] Use Maven3 to import projects

I have to check the Maven3 import option and that fixes the issue.

Answer 3

Yet another solution on IntelliJ Ultimate 2018.2

• Hover over the import marked red
• Select dropdown arrow on the popup that appears on left (below)
• Choose "Add library ... to classpath"

Answer 4

Resolved by simply "Refresh All Gradle Projects"

Answer 5

I had the same issue I was using JDK 1.9 with IntelliJ 14, I solved reinstalling Java with latest version of JDK 1.8(1.8.0_161 in this case)

I also removed the 1.9 version from

HKEY_CURRENT_USER\Software\JavaSoft\JRE\Security Baseline

Answer 6

Try to delete the .IntelliJIdea15(depends on version) from C:\Users\Username

When you start IntelliJ it will create the folder again.