The superclass "javax.servlet.http.HttpServlet" was not found on the Java Build Path

The superclass “javax.servlet.http.HttpServlet” was not found on the Java Build
Path
해결방법 : 프로젝트 마우스 우 클릭 -> Build Path -> Configure Build Path -> 세번째 탭 Libraries -> 우측 네번째 Add Library 클릭 -> server runtime ->선택 후 Apply 하면 해결 됨