IntelliJ IDEA
To add the plugin, start the IDE and find the Plugins dialog. Browse Repositories, choose Category: Build, and find the Error-prone plugin. Right-click and choose “Download and install”. The IDE will restart after you’ve exited these dialogs.

To enable Error Prone, choose Settings | Compiler | Java Compiler | Use compiler: Javac with error-prone and also make sure Settings | Compiler | Use external build is NOT selected.