When working in a Java environment with multiple developers using their own IDE preference I often get error like this opening a project with IntelliJ: “@Override is not allowed when implementing interface method”. Since I’m not a Java dev fulltime I tend to forget this stuff, so basically this is a reminder for myself …
Basically IntelliJ thinks the project is Java 1.5 by default so while my console / mvn build works perfectly due to using Java 8 the IDE thinks differently.
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<configuration>
<source>1.8</source>
<target>1.8</target>
</configuration>
</plugin>
Project Language
File > Project Structure > Project > Language level
Module Language
If your project has multiple modules check that they inherit the project language, or when needed, set the correct non-default on the module
File > Project Structure > Module > Language level
or
Right Click module > Open Module Settings
Java Compiler for Default Projects
While your at it, set this value as a default for new projects as well
File > Other Settiings > Default Settings > Build, Execution, Deployment > Compiler > Java Compiler > Project Bytecode version
