스프링 프로젝트 에러

intellij
File > Project Settings > Project > Project SDK > 사용중인 JDK 버전 apply
https://stackoverflow.com/questions/4618794/intellij-idea-cannot-resolve-symbol-and-cannot-resolve-method
Cannot resolve symbol 'Long' -> 'java'가 될 수도 있고~

cannot start compiler the sdk is not specified for module ... Specify the SDK in the Project Structure dialog
https://atoz-develop.tistory.com/entry/IntelliJ-SDK-JDK-%EC%84%A4%EC%A0%95-%EB%B0%A9%EB%B2%95-cannot-start-compiler-the-sdk-is-not-specified