The superclass “javax.servlet.http.HttpServlet” was not found on the Java Build Path [duplicate]

Add a runtime first and select project properties. Then check the server name from the ‘Runtimes’ tab as shown in the image.

Include servlet-api-3.1.jar in your dependencies.

Maven

javax.servlet
javax.servlet-api
3.1.0
provided

Gradle
configurations {
provided
}
sourceSets {
main { compileClasspath += configurations.provided }
}
dependencies {
provided ‘javax.servlet:javax.servlet-api:3.1.0’
}